RS3 DCS Controller Configuration

Transcription

Engineering and Construction Specifications
Division 17 - Instrumentation
Title: RS3 DCS Controller Configuration
Revision: 5
Document #: CS17130
Revision Date: 04/05/2016
SECTION INDEX
Page: 1 of 81
Effective Date: 04/05/2016
SHEET NO.
PART 1 GENERAL
1.01
General Controller Configuration ----------------------------------------
2
PART 2 EXECUTION
2.01
Regulatory Control ----------------------------------------------------------
9
2.02
Flow Totalizers ---------------------------------------------------------------
12
2.03
Motor Control -----------------------------------------------------------------
13
2.04
On/Off Valve Control -------------------------------------------------------
27
2.05
Interlocks/Shutdowns -------------------------------------------------------
36
Appendix A- Configuration Examples
A.1
AIB I/O Block -----------------------------------------------------------------
40
A.2
AOB I/O Block ----------------------------------------------------------------
40
A.3
CIB/DIB I/O Block -----------------------------------------------------------
41
A.4
COB/DOB I/O Block --------------------------------------------------------
41
A.5
TIB Block ----------------------------------------------------------------------
42
A.6
Manual Block -----------------------------------------------------------------
43
A.7
PID Control Loop ------------------------------------------------------------
45
A.8
Cascade Control Loop -----------------------------------------------------
47
A.9
Ratio Control Loop ----------------------------------------------------------
50
A.10
Stack Totalizer ---------------------------------------------------------------
53
A.11
Group 1 – Start/Stop Motor -----------------------------------------------
56
A.12
Group 2 – Start/Stop Motor -----------------------------------------------
64
A.13
Fail-Closed Valve ------------------------------------------------------------
65
A.14
Fail-Open Valve --------------------------------------------------------------
71
A.15
Motor Control Schematic --------------------------------------------------
77
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PART 1
1.01.
Document #: CS17130
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GENERAL
General Controller Configuration
A.
Control Processor Setup
1.
The MPC scan time for all control processors shall be set to 1.0
second. All loops shall be configured to operate at the MPC scan
time. All loops that require less than 1 sec scan time will be
configured on the same MPC (e.g. batch charging).
2.
Local Inhibit shall be set to "YES".
3.
Control processor redundancy shall be specified by the project team.
4.
The Status of every MPC (multipurpose controller) card must be
“Norm” (Normal) to provide control functionality. After a power cycle
(beyond where battery backup is active (> 15-20 minutes typically)),
all MPC cards power up in “Stby” (Standby) mode as a safety feature
built in to the RS3 system. In Standby mode, all control blocks can
read inputs and track signals but cannot generate a link or set outputs
to any other control block or to the field. It is recommended that
configuration be provided to automatically set each MPC card to
Normal mode so that the process control system automatically
resumes control functionality after power cycles. If certain Control
Blocks should power up in Standby mode, requiring operator input to
place the card in Normal mode after conditions are safe, then these
Control Blocks should be segregated to one MPC card in an area and
configuration to automatically set that MPC card to Normal mode
(shown below) should not be configured.
To automatically set a MPC card to Normal mode, configure the last
logic step (p) in the last Control Block of the MPC card as follows:
p=> 1
On=> snorm
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B.
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I/O Block and Control Block Tag Name Convention
1.
Point tags in the Rosemount RS3 can contain a maximum of sixteen
(16) alphanumeric characters.
2.
All Control Blocks will have the same tag name as indicated on the
P&ID’s, which includes a 3-digit number prefix designating the plant
area followed by a “-“. Therefore it is recommended that the Tag
Mask be set to mask the first 4 digits of tag names. Note, with the
Tag Mask set this way, the actual tag names include the area number
prefix, but faceplate displays do not show the prefix.
3.
The input/output point (I/O block) will have the same tag name as the
field device tag name.
4.
Below are examples showing the tag name convention for analog
devices and controllers.
I/O Block Tags (Block Type)
069-FT-V10A (AIB)
069-FY-V10A (AOB)
069-PT-V10A (AIB)
069-PY-V10A (AOB)
069-LT-V10A (AIB)
069-LY-V10A (AOB)
069-SI-P102 (AIB)
069-SY-P102 (AOB) – speed output 4-20ma
069-AIT-V10A (AIB)
069-AY-V10A (AOB)
069-TT-V10A (AIB)
069-TY-V10A (AOB)
069-TIT-V10A (AIB)
069-TE-V10A (TIB)
Controller Block Tags (Block Type)
069-FIC-V10A (PID)
069-FI-V10A (MAN)
069-PIC-V10A (PID)
069-PI-V10A (MAN)
069-LIC-V10A (PID)
069-LI-V10A (MAN)
069-SIC-P102 (PID)
069-SI-P102 (MAN)
069-AIC-V10A (PID)
069-AI-V10A (MAN)
069-TIC-V10A (PID)
069-TI-V10A (MAN)
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5.
Document #: CS17130
Below is the tag name convention for discrete motor-driven devices
and controllers. IO tag names reflect motor switches and confirms.
The controller tag name is the name of the device that is operated by
the motor.
Motor Start/Stop Output (COB/DOB)
Motor Start Ouput (COB/DOB)
Motor Stop Output (COB/DOB)
Motor Status Input (CIB/DIB)
Pump Motor Control Block (DMC)
Agitator Motor Control Block (DMC)
Where
6.
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HS
HR
HI
R
S
I
P
A
####
069-HS-####
069-HR-####
069-HS-####
069-HI-####
069-P-####
069-A-####
= Hand (Electric) Start / Stop Switch
= Hand (Electric) Run Switch
= Hand (Electric) Switch Indicator – motor status
= Run Command
= Stop Command
= Run Confirm
= Pump
= Agitator
= Device Name from P&ID’s
Below is the tag name convention for discrete valves and controllers.
IO tag names reflect valve position switches and actuating solenoid
valve. The controller tag name is the same as the valve name.
Actuated Discrete Valve with Indication Switches
Solenoid Valve Output (COB/DOB)
069-SV-#####
Open Limit Switch Input (CIB/DIB)
069-ZSO-#####
Closed Limit Switch Input (CIB/DIB)
069-ZSC-#####
Discrete Valve Control Block (DVC)
069-XV-#####
Actuated Discrete Valve with No Indication Switches (Solenoid Valve)
Solenoid Valve Output (COB/DOB)
069-SV-#####
Discrete Valve Control Block (DVC)
069-XV-#####
Non-Actuated Discrete Valve with Indication Switches Only
Open Limit Switch Input (CIB/DIB)
069-ZSO-#####
Closed Limit Switch Input (CIB/DIB)
069-ZSC-#####
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Discrete Valve Monitor Block (DISC)
Where
7.
SV
ZSO
ZSC
XV
HV
Page: 5 of 81
069-HV-#####
= Actuating Solenoid Valve
= Open Position Switch
= Closed Position Switch
= Actuated Discrete Valve
= Hand Operated Valve
Below is the tag name convention for limit switches and alarms.
069-LSL-#####
069-LAL-#####
069-TSH-#####
069-TAH-#####
069-TSHH-#####
069-TAHH-#####
low level field switch input block (CIB/DIB)
alarm for low level switch (DISC)
HI temp field switch input block (DIB/CIB)
alarm for HI temp switch (DISC)
HHHI temp field switch input block (DIB/CIB)
alarm for HIHI temp switch (DISC)
8.
Control Blocks used for executing Interlock logic shall be tagged with
letter “I” preceded by the area number and followed by a sequential
three-digit number. This naming convention should be used
independent of whether the trip signal is linked to the Control Block @j
“shutdown” or @k “interlock” register. For example, the first Control
Block tag name for interlocks in the Area 69 is 069-I-001, the second
069-I-002. An interlock Control Block may contain multiple inputs for
a particular interlock and multiple outputs (interlocks for multiple
devices).
9.
When the second letter in an output block tag name is "Y", such as
069-FY-#####, it indicates that the output block is an analog signal
connected to a signal converter such as an I/P transducer or a
frequency drive. If the second letter in a Control Block tag name is a
"Y", the Control Block is a calculation Control Block used internally by
the DCS.
10.
When using multiple signal conditioners or calculation blocks within a
single control loop use alpha characters as suffixes to distinguish
each signal conditioner or calculation block. The letter "A" should be
used as the suffix for the I/P transducer in the loop. For example, a
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flow control loop 069-FIC-##### has a lead/lag Control Block for a
signal conditioner and an I/P transducer connected to an AOB. The
AOB tag name should be 069-FY-#####A and the lead/lag signal
conditioner Control Block tag name should be 069-FY-#####B.
11.
Each Control Block will be given a 24-character word descriptor. The
Control Block descriptor is displayed on the faceplate when selected
from a process graphic. The descriptor spans three lines with each
line containing 8 characters each. If a Control Block alarm is
configured, the descriptor will be displayed at the console screen
bottom in a single line when the alarm occurs. The appropriate
message pair or process variable value will also be displayed with the
alarm.
12.
Do not exceed 7 characters on lines 1 and 2 if all three lines will be
used. Always use a semicolon when entering the descriptor to start
the next line. Remember 8 characters can be used on the last line.
See the examples below.
Descriptor Entry
B26 MC;TRAY #2
B26 FC;REBOILER
B26;RESIDUE;
RECEIVER
Faceplate
B26 MC
TRAY #2
B26 FC
REBOILER
B26
RESIDUE
RECEIVER
Alarm Banner
B26 MC TRAY #2
B26 FC REBOILER
B26 RESIDUE RECEIVER
As shown, the semicolon makes the vertical faceplate descriptor and
alarm banner both easy to read. If spaces were used instead of the
semicolon to make the faceplate look the same, the alarm banner
would have additional spaces between words (see example below)
Descriptor Entry
B26
RESIDUE
RECEIVER
Faceplate
B26
RESIDUE
RECEIVER
Alarm Banner
B26 RESIDUE
RECEIVER
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13.
C.
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Test all alarms and verify the alarm banner is easy to read and
understand.
Analog Inputs
1.
Hardware alarms for analog inputs, if used, shall be set as follows
(these correspond to 1 mA over and under the standard 4-20 mA
range):
Inst High = 106.25%
Inst Low = -6.25%
2.
All analog inputs will have the Low Cut-Off set as follows:
Low Cut-Off=-10% of span in Engineering Units
D.
3.
Critical and Advisory process alarms SHALL NOT be entered on AIB
blocks whose output is linked and displayed in a Control Block (e.g.
RS, PV, FF, RV signals). The alarm limits shall be entered on the
Control Block Continuous Diagram Page.
4.
Example A.1 describes the detailed configuration for an AIB I/O block
Discrete Inputs
1.
Field devices that generate alarms, such as temperature and pressure
switches, shall be wired fail safe, (de-energized=alarm). The alarm
then generates when the DCS receives an OFF signal.
2.
The default CIB/DIB block configuration is as follows:
Field Contact = NO
Filter Type = None
3.
Example A.2 describes the detail configuration for a DIB/CIB I/O
block.
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Discrete Outputs
1.
The default COB/DOB block configuration is as follows:
Contact Type = NO
Output Hold = None
2.
F.
G.
Examples of discrete output I/O block configurations are described for
motor control and ON/OFF valve control in sections A.11 through A.14
Pulse IO Inputs
1.
When the flow measuring instrument sends a pulsed or frequency
signal to the DCS, the device must be wired to a pulse-type FIC card
and the IO block must be configured as a pulse input/output block
(PIOB). Note: a Smart 4-20 mA transmitter is preferred.
2.
A PIOB can be configured to measure frequency of pulses (where
frequency is typically proportional to process variable, e.g., flow rate),
duration of pulses (output is in seconds), or to count pulses.
3.
PIOB’s link to Control Blocks. Frequency and duration PIOB outputs
send an analog signal (derived from the pulses) to the Control Block.
The analog range is entered on the PIOB measuring frequency (and
on the Control Block input register); the analog range for duration type
PIOB’s is the range on the Control Block input register in engineering
units corresponding to the duration of the pulses in the PIOB. A PIOB
configured to measure counts is typically used to totalize based on
counts received from a device. See “Flow Totalizers” in Section 2.02
below.
Modes Definitions for RS3 systems
1.
IO blocks can be in Manual or Auto mode and are normally locked in
Auto mode (input block reads field signals, output block reads Control
Block link). Input IO blocks can be simulated in Manual mode and
output IO blocks can be forced in Manual mode.
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2.
RS3 Control Blocks can be in one of four modes: Local,
Operator/Manual, Auto, and Remote. Modes operate differently in
different Control Block types. For Continuous Functions like PID
controllers, mode determines the action of the output Q register alone.
For Discrete Motor and Valve Controllers (DMC and DVC), mode
determines which discrete inputs act to start or stop the device. For
all types of Control Blocks, the actions of Control Block logic steps are
determined by each logic step’s mode which can be either Manual or
Auto. Any logic step in Manual mode is listed at the bottom of the
Control Block discrete diagram pages.
3.
Local mode is the initial mode a Control Block is in after it is created
or after the block has been modified in certain ways, e.g., a register
has been deleted. In Local mode, the operator directly manipulates Q
from the console and Q cannot be overridden by logic.
4.
Operator/Manual mode: for PID controllers, the operator directly
manipulates Q from the console and Q can be overridden by logic.
For DMC’s and DVC’s, the device is started by pressing the
“OPERATOR >start” button (linked to @a momentary ON discrete
input) on the faceplate from the console, and the device is stopped by
pressing the “OPERATOR >stop” button (linked to @b momentary ON
discrete input) on the faceplate from the console. Auto start (linked to
@d discrete input) and Auto stop (linked to @e discrete input) states
are ignored.
5.
Auto mode: for PID controllers, the controller function manipulates Q
to attempt to make the process variable PV equal to the local setpoint
LS, and Q can be overridden by logic. For DMC’s and DVC’s, the
device is started by other controllers linked to or batch tasks writing to
the Auto start discrete input link @d and the Auto stop discrete input
link @e. In Auto mode, the “OPERATOR >start” and “OPERATOR
>stop” buttons are ignored.
6.
Remote mode: This is the normal mode for cascade slave
(secondary) PID loops. The controller function manipulates Q to
attempt to make the process variable PV equal to the remote setpoint
RS (linked to a master (primary) PID loop output), and Q can be
overridden by logic. Remote mode does not apply to DMC’s and
DVC’s.
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PART 2
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EXECUTION
Regulatory Control
A.
General PID Loop Configuration
1.
Regulatory control valves shall be configured such that 0% output on
the control faceplate implies a closed valve-position, and 100%
implies a fully opened valve. For "Fail-Open" (FO) valves, the output
action on the AOB block shall be configured as REVERSE acting.
2.
Output High and Low Limits shall be configured as 100% and 0%
respectively unless otherwise specified or for a master cascade loop.
3.
High and Low Limits for Setpoint, Ratio, Remote Setpoint, etc. shall
correspond with their Eng Zero and Eng Max values.
4.
The ACTION field on the Continuous Faceplate screen of regulatory
control loops specifies whether the controller output is direct or
reverse acting. A controller whose output increases with a decreasing
process variable is defined as REVERSE acting.
The controller
action and the AOB action are independent settings.
5.
The local setpoint (LS) shall not track PV unless specified by project
team.
6.
Output tracking logic shall be generated within the Control Block logic
steps a-p. When the output is to track another variable originating
outside of the Control Block, the variable shall be linked through
continuous register-G of the PID Control Block.
7.
The CONVERT field on the CB Continuous Links page shall be left
blank, resulting on no conversion (to engineering units or normalized
units). Any conversions to different scaling should be done in the Eng
Zero and Eng Max fields of analog registers and in math expressions
in logic steps.
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8.
The HOLD FORWARD option on the CB Continuous Links page shall
be configured "NO" for all inputs with potential affect to the output of a
PID Control Block (e.g. PV, FF, RV, etc.).
9.
Default Configuration for PID block options shall be as follows:
PI Action
Derivative Action
LS-PV Track
Setpoint Rate Limit
Output Rate Limit
10.
B.
Error
PV
No
None
None
Example A.7 describes the setup of a standard PID Control Block.
Default Tuning Constants
Control Type
Flow
Temp. (Slow loop)
Temp. (Fast loop)
Level
Pressure (Slow loop)
Pressure (Fast loop)
C.
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Gain
0.50
5-10
1.50
2-5
2.50
0.50
Integral Time (I)
10.0 sec
10.0 min
1.0 min
5-10 min
1.0 min
10.0 sec
Derivative Time (D)
0.0 sec
60.0 sec
0.0 sec
0.0 sec
0.0 sec
0.0 sec
Alarm Setpoints
1.
The project team or Production Engineering shall specify all required
alarm settings.
2.
Unless otherwise specified, the Critical High and Low alarms shall be
95% and 5% of the signal span and Advisory High and Low alarms
shall be 90% and 10% of span with a 2% Dead Band.
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D.
E.
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Cascade Control
1.
For all cascade control strategies, the slave loop LS shall
configured to track the PV in the MANUAL mode. Additionally,
TRACK INPUT field of the slave loop should be set equal to
Remote Setpoint (RS) so that the master loop output will track
slave LS when the slave loop is in MANUAL or AUTO.
be
the
the
the
2.
If the slave loop contains logic affecting the controller output (Q), a
logic step of the master loop shall be configured such that the master
loop output tracks the LS of the slave loop as long as the logic is
active. To accomplish this, the Logic Active Status Bit (LA) of the
slave loop will be linked via discrete input register-@a (e.g. Input
@a='slave loop tag/LA') and tested in the master loop logic. The LS
of the slave loop shall be linked to continuous register-G in the master
loop. If logic is active on the slave loop output, LA will be true and the
output of the master loop shall track register-G (LS of the slave loop).
3.
Section A.8 provides a sample configuration for a Cascade Control
Loop.
Ratio Control
1.
A ratio controller is configured by selecting the RATIO option on the
PID block Continuous Faceplate Display. Ratio control is active when
the PID block is in the REMOTE mode. The RATIO option provides
for calculation of the Remote Setpoint (RS) from the formula:
Where
2.
RS
RV
RA
BI
=
=
=
=
RV*RA+BI
Ratio Variable or Wild Variable
Ratio Factor
Bias
Continuous input-B (LS) shall be selected and highlighted on the
Continuous Faceplate so that it is enterable from the operator
keyboard when selected from the process graphic. The Discrete
Faceplate side of the loop shall be configured for operator entry of the
Ratio.
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3.
4.
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On the Continuous Links Display, the SOURCE fields shall be entered
as follows:
PV = AIB block tag (controlled)
LS = *ENTRY
RS = *VALUE
RV = AIB block tag (wild)
RA = *ENTRY
BI = *NONE, 0, or a constant value
The ENG ZERO value for RA shall equal 0; the ENG MAX value for
RA is calculated from the formula:
ENG MAX RA = (MAX PV - ZERO PV) / (MAX RV - ZERO RV)
2.02
5.
The HOLD FORWARD option for both the PV and RV shall be
configured as “NO”.
6.
Section A.9 provides an example of a Ratio Control Loop.
Flow Totalizers
A.
Two types of totalizers are available for use with analog flow meters: a
SETPOINT TOTALIZER and a STACK TOTALIZER. Both integrate a flow
rate signal received from the AIB or PIOB (frequency or duration type only)
I/O block and the accumulated value is collected in the output Q register.
Both totalizers can be configured to reset Q to zero automatically (when Q
reaches the Output High Limit) or manually by using a logic step to set Q to
zero when a momentary button is pressed on the totalizer faceplate. The
stack totalizer can also reset Q to zero periodically based on time (e.g., reset
Q every 24 hours). If the “treset” function is used to reset the stack totalizer,
the last three totalized values (between resets) will be stored in registers B,
C, and D.
B.
Totalizers totalize the PV input signal times gain K. K is normal set at 1, but
can be different if the units of the IO block are different from the desired
totalized units. For example, set K=2.2 if the AIB IO block is kg/min and the
desired totalized value is lb; or set K=.001 if the AIB IO block is lb/min and
the desired totalized value is M lb (thousand lb).
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C.
The integration time is the time that it takes the output to go from 0% to 100%
when the input is at 100%. Set the integration time so that the output does
not exceed 100% between resets. Note: the output Q does totalize beyond
100% but will not be visible via the bar display if allowed to do so.
D.
Totalizer integration is active (Q values accumulate) in Auto mode and
inactive (Q value freezes) in Operator/Manual mode. Placing a totalizer in
Operator/Manual mode does not reset the Q value to zero – resetting Q is a
separate operation.
E.
Non-analog flow meters that send pulse signals to indicate volume amounts
can be totalized using the pulse input/output block (PIOB). The PIOB is
configured as a counter and linked to a Control Block to totalize counts. The
output of the PIOB shall be linked to a DISC Control Block to provide target
values and reset flags. The target value and reset flags in the Control Block
are communicated back to the PIOB to reset the PIOB counter. The
engineering units associated with the counts (e.g., “FT is calibrated at 100
gallons per count”) should be documented as a comment in the DISC Control
Block.
F.
When using a PIOB to count the number of pulses, set the “Prescale” value
equal to Maximum input frequency/500 Hz. If the exact value is not available,
choose the next greater option available. A prescale value of n increments
the PIOB counter by 1 for each n input pulses.
G.
The target values configured in the DISC block are in counts, so totalizing to
and engineering unit endpoint must consider the number of engineering units
associated with a count.
Motor Control
A.
Motor Control Philosophy
Note on DMC discrete motor controllers: Logic steps c, i, and l can be
configured only using MPC2 or MPC5 controllers. Logic in these steps using
MPC1 controllers will not work.
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Motors controlled from the DCS fall into one of the three following
groups:
Group 1
The DCS as well as local start/stop stations can operate motors in
Group 1. Motor run status is displayed on the DCS. Two momentary
digital outputs from the DCS are used for the start and stop command
and local start/stop stations are also monetary. All future installations
will utilize this design (see example A.11). Refer to the schematic in
example A.16 for MCC detail.
Group 2
The DCS as well as local hand/off/auto (HOA) stations can operate
motors in Group 2. Motor run status is displayed on the DCS. A
single latching digital output from the DCS is used for the start/stop
command, mimicking the operation of field HOA switches. Group 2
motors exist throughout the plant but no future installations of this
design will be allowed (see example A.12).
Group 3
Local start/stop (or HOA) stations only can operate the motor. Motor
run status is displayed on the DCS.
2.
B.
All DCS controlled motors shall be equipped with field mounted
START/STOP buttons that retain an equal control priority with the
DCS under normal process conditions. If a process interlock is active
on the DCS, the interlock shall prevent operation of the device from
the DCS and all field START buttons. This is only possible with
Group 1 motor controllers.
Motor Control Configuration (Group 1)
1.
The DMC Control Block shall be used to control motors with both DCS
start and stop capability.
2.
In general, options (found on Continuous Faceplate) for the DMC
block shall be configured as follows:
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STRT TMR Target
STOP TMR Target
Interlock
Confirm Off
Retry
Security Lockup
Trip Delay
MCC Alarm
Ignore Confirm On
3.
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5 sec
2 sec
Yes or No
No
No
No
No
No
No
DMC links shall be as follows. Only those differing from the DMC
defaults are shown. CB is an abbreviation for the Control Block.
Input
@d
@e
@g
@k
@n
A
B
C
K
Source
Eng Zero
Eng Max
Units
CB/A
CB/B
run confirm CIB/DIB
*ON – if no interlock address is linked
*VALUE – written to from batch task
*VALUE
0
1
AUTO ON
*VALUE
0
1
AUTO OFF
*VALUE
0
1
MODE
*TIMER
0
1
SECS
If applicable, a signal representing all process interlocks shall be
linked to @k. The @k link interlocks the DMC OFF if the signal is
OFF. The DMC interlock can be bypassed with a supervisor’s key. If
applicable, a signal representing all process shutdowns shall be linked
to @j. The @j link shuts the DMC OFF if the signal is ON. The DMC
shutdown cannot be bypassed. If @k or @j links are used, they shall
be displayed on the faceplate.
4.
The start output from the DCS to the motor control circuit shall be a
normally open (NO) momentary contact, mimicking field START
buttons The stop output from the DCS to the motor control circuit
shall be a normally closed (NC) momentary contact, mimicking field
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STOP buttons. The action directions (NO or NC) of the DCS outputs
are determined by a combination of the logic in the steps linked to the
output IO blocks, the output IO block contact type, and the optical
isolator (opto) type. The pulse logic of the contact output can be
configured in the logic step or by latching the logic step and setting
the OUTPUT HOLD field in the output IO block to “pulse” and entering
a HOLD TIME.
5.
Logic step “a” shall be linked to the DCS start contact/discrete output
block (COB/DOB). Step “a” of a DMC contains default logic that
latches step “a” ON to start and latches step “a” OFF to stop. The
COB/DOB linked to the “a” logic step shall be configured as Contact
Type “NO”, Output Hold “None”, and use a NO opto. The “a” output
step cannot be turned ON if an interlock or shutdown is active.
6.
Logic step “m” shall be linked to the DCS stop contact/discrete output
block (COB/DOB). Step “m” of a DMC contains user-configured logic
(see below) that latches step “m” ON to stop and latches step “m”
OFF to allow to start. The COB/DOB linked to the “m” logic step shall
be configured as Contact Type “NC”, Output Hold “Pulse”, Pulse Time
“3 sec”, and use a NO opto. The resulting output to the motor control
circuit is a normally closed momentary ON when step m transitions
from OFF to ON, mimicking field stop buttons. The “m” output step
cannot be turned OFF if an interlock or shutdown is active or if the
Control Block is in Auto mode with Auto STOP active.
7.
The table below summarizes the start and stop output command
configuration for Group 1 DMC’s.
Block Input
Block Output
Contact Type
Output Hold
Hold Time
Opto Type
Opto Fail State
Start COB/DOB
DMC Step “a”
control circuit DCS start
NO
Pulse
3 sec
NO
Stop
Stop COB/DOB
DMC Step “m”
control circuit DCS stop
NC
NONE
------NO
Stop
Revision: 5
8.
9.
10.
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The motor run confirm shall be linked to discrete input @g. The table
below summarizes the run confirm configuration for Group 1 DMC’s.
Run Confirm CIB/DIB
Block Input
motor controller auxiliary contacts
Block Output
DMC link @g
Field Contact
NO
Filter Type
None
Opto Type
NO
Opto Fail State
Stopped
Logic conditions and actions can be configured on the Control Block
Discrete Diagrams screen. Each Control Block has 16 Discrete
Diagrams or “steps”, steps a-p, but many are pre-configured and not
available for user-configuration. RS3 uses a double “==” as a
”relational equality” and a single “=” as an “assignment”. For instance,
x==y means “if x is equal to y, the expression is true”, and x=y means
“write the value of y to x”. Place only conditions in the top
CONDITIONS window. For instance, the expression C=5.5 should
not be entered on the CONDITIONS window (it works but this is
unnecessary and confusing). Rather, to accomplish this enter “1” in
the logic step field in the CONDITIONS window (turning the step ON)
and enter C=5.5 in the ON field in the ACTIONS window.
The actions in logic step “a” write a single discrete input @n to analog
registers A and B (A equals the state of @n, B equals the opposite
state). The values in analog registers A and B are written to @d and
@e discrete inputs (see above), which are the Auto Start and Auto
Stop input registers for DMC Control Blocks. This configuration
allows a single discrete input (@n) to toggle the DMC from Auto Start
to Auto Stop. If the @n input alone acts on the Auto Start/Stop
command, logic step “a” shall be configured as follows:
a=> Predefined function
On=>A=@n; B=~@n
Off=>A=@n; B=~@n
The ~ symbol represents “NOT”
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If other data besides the @n input acts on the Auto Start/Stop
command or if actions are required when the Auto Start/Stop
command is changed, logic step “a” shall be modified as follows:
On=>A=n; B=~n
Off=>A=n; B=~n
11.
Logic step n would then contain @n, other data that activates the Auto
Start/Stop command, and perhaps actions that occur when the Auto
Start/Stop command is changed.
Logic step “b” can be used to lock motors that are not started
automatically (only started by the DCS console keyboard, not by
another DCS device or batch task) in OPERATOR mode. For motors
requiring this, logic step “b” shall be configured as follows:
b=> Predefined function
On=> setmode 1
Off=> setmode 1
12.
Logic step “c” can be used to change the Control Block mode based on
a value written to it from a batch task. If batch tasks are used to
change Control Block mode, the logic step “c” shall be configured as
follows:
c=> C>0
Rise=> setmode C
On=> C=0
Writing a 1 to the C registers changes the Control Block mode to
Operator/Manual, 2 to Auto, and 3 to Remote. Note: if using a MPC I
controller, logic in step c will not work. If this logic is required, move it
to step p.
13.
Logic step “d” is used to set the 15 user flags of the A analog register
equal to the 16 Control Block discrete input values. These user flags
can then be linked to other Control Blocks and graphic objects
(discrete input links cannot be linked to other Control Blocks or
graphic objects). Logic step “b” shall be configured as follows:
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d=> Predefined function
On=> A.u=R.u
Off=> A.u=R.u
For example, with A.u=R.u true in Control Block P-100, discrete input
@e is linked to another Control Block or graphic object by linking P100/A/e (or in some cases P-100.A.e).
14.
Logic step “e” is a predefined step which turns ON when the device
fails (e.g., the motor fails to start within 5 seconds of a DCS start
command, or the run confirm of a running motor is lost). This should
trip a critical alarm. Logic step “e” shall be configured as follows:
e=> Predefined function
Rpt> Crit
When> On
15.
Logic step “l” may be configured to provide an advisory alarm if the
motor is started from the field. The alarm will clear when a DCS
START command is issued (either automatically or manually), or the
motor subsequently stops. Logic step “l” shall be configured as
follows:
l=>(rise @g)&~a
Rpt> Adv
When> Rise
Note: if using a MPC I controller, logic in step l will not
work. If this logic is required, move it to step p.
16.
Logic step “m” for Group 1 motors shall be used to drive the DCS stop
COB/DOB and shall be configured as follows:
m=>~(@k|d)
SET >(@b&(mode==1))|(@e&(mode==2))|e|@j
CLEAR >wait(3,K,m)&~(@e&(mode==2))&~@j&(@k|d)
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The “m” step output is linked to the motor control circuit DCS stop
COB/DOB. Under normal conditions, step m pulses ON for 3
seconds after either the manual or auto stop command is
activated. The m step instead latches ON if an interlock or
shutdown is active or if the Control Block is in Auto mode with
Auto Run active. The COB/DOB reverses the “m” step signal so
the resulting output acts like a NC momentary button under
normal conditions and a button latched OFF under interlock
conditions, preventing devices from being started even from field
start stations.
17.
Logic step “n” is used if other data besides the @n input acts on the
Auto Stop/Start command or if actions are required when the Auto
Stop/Start command is changed. Below are examples of how logic
step “n” may be configured:
n=> @n
Rise=> setmode 2
Fall=> setmode 2
or
n=> @n&(L<25)
18.
Logic step “o” shall be used to provide a critical alarm when an
interlock or shutdown becomes active while the device is running.
Logic step “o” shall be configured as follows:
o=> (@j|~@k)&@g
Rpt> Crit
When> Rise
C.
1.
The DMC Control Block shall be used to control motors with both DCS
start and stop capability.
Revision: 5
2.
Document #: CS17130
In general, options (found on Continuous Faceplate) for the DMC
STRT TMR Target
STOP TMR Target
Interlock
Confirm Off
Retry
Security Lockup
Trip Delay
MCC Alarm
Ignore Confirm On
3.
Page: 22 of 81
5 sec
2 sec
Yes or No
No
No
No
No
No
No
DMC links shall be as follows. Only those differing from the DMC
Input
@d
@e
@g
@k
@n
A
B
C
Source
Eng Zero
Eng Max
Units
CB/A
CB/B
run confirm CIB/DIB
*VALUE
0
1
AUTO ON
*VALUE
0
1
AUTO OFF
*VALUE
0
1
MODE
linked to @k. The @k link interlocks the DMC OFF if the signal is
OFF. The DMC interlock can be bypassed with a supervisor’s key. If
applicable, a signal representing all process shutdowns shall be linked
to @j. The @j link shuts the DMC OFF if the signal is ON. The DMC
shutdown cannot be bypassed. If @k or @j links are used, they shall
be displayed on the faceplate.
4.
The single start/stop output from the DCS to the motor control circuit
shall be a latched contact, mimicking field HOA switches.
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5.
Logic step “a” shall be linked to the DCS start/stop contact/discrete
output block (COB/DOB). Step “a” of a DMC contains default logic
that latches step “a” ON to start and latches step “a” OFF to stop. The
COB/DOB linked to the “a” logic step shall be configured as Contact
Type “NO”, Output Hold “None”, and use a NO opto. The “a” output
step cannot be turned ON if an interlock or shutdown is active.
6.
The table below summarizes the start/stop output command
configuration for Group 2 DMC’s.
Block Input
Block Output
Contact Type
Output Hold
Hold Time
Opto Type
Opto Fail State
7.
Block Input
Block Output
Field Contact
Filter Type
Opto Type
Opto Fail State
8.
Start COB/DOB
DMC Step “a”
control circuit DCS start/stop
NO
None
------NO
Stop
Run Confirm CIB/DIB
DMC link @g
NO
None
NO
Stopped
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9.
@e discrete inputs (see above), which are the Auto Start and Auto
Stop input registers for DMC Control Blocks. This configuration
allows a single discrete input (@n) to toggle the DMC from Auto Start
to Auto Stop. If the @n input alone acts on the Auto Start/Stop
On=>A=@n; B=~@n
Off=>A=@n; B=~@n
If other data besides the @n input acts on the Auto Start/Stop
command or if actions are required when the Auto Start/Stop
On=>A=n; B=~n
Off=>A=n; B=~n
Start/Stop command, and perhaps actions that occur when the Auto
Start/Stop command is changed.
10.
Logic step “b” can be used to lock motors that are not started
automatically (only started by the DCS console keyboard, not by
another DCS device or batch task) in OPERATOR mode. For motors
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On=> setmode 1
Off=> setmode 1
11.
Logic step “c” can be used to change the Control Block mode based
on a value written to it from a batch task. If batch tasks are used to
follows:
c=> C>0
Rise=> setmode C
On=> C=0
to step p.
12.
On=> A.u=R.u
Off=> A.u=R.u
For example, with A.u=R.u true in Control Block P-100, discrete input
@e is linked to another Control Block or graphic object by linking P100/A/e (or in some cases P-100.A.e).
13.
fails (e.g., the motor fails to start within 5 seconds of a DCS start
command, or the run confirm of a running motor is lost). This should
trip a critical alarm. Logic step “e” shall be configured as follows:
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Rpt> Crit
When> On
14.
Logic step “l” may be configured to provide an advisory alarm if the
motor is started from the field. The alarm will clear when a DCS
START command is issued (either automatically or manually), or the
motor subsequently stops. Logic step “l” shall be configured as
follows:
l=>(rise @g)&~a
Rpt> Adv
When> Rise
Note: if using a MPC I controller, logic in step l will not
work. If this logic is required, move it to step p.
15.
Auto Stop/Start command or if actions are required when the Auto
Stop/Start command is changed. Below are examples of how logic
n=> @n
Rise=> setmode 2
Fall=> setmode 2
or
n=> @n&(L<25)
16.
interlock or shutdown becomes active while the device is running.
Logic step “o” shall be configured as follows:
o=> (@j|~@k)&@g
Rpt> Crit
When> On
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D.
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1.
A Manual or Discrete Control Block shall be for motors with DCS
indication only.
2.
All Group 3 motors shall be locked into the AUTO mode by
configuring step-b ACTION as follows:
On=> setmode 2
Off=> setmode 2
3.
Block Input
Block Output
Field Contact
Filter Type
Opto Type
Opto Fail State
4.
Run Confirm CIB/DIB
DMC link @g
NO
None
NO
Stopped
On=> A.u=R.u
Off=> A.u=R.u
2.04
ON/OFF Valve Control
Note on DVC discrete valve controllers: Logic steps c, i, and l can be
configured only using MPC2 or MPC5 controllers. Logic in these steps using
MPC1 controllers will not work.
Revision: 5
A.
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General
1.
The DVC Control Block shall be used to control ON/OFF valves.
2.
In general, options (found on Continuous Faceplate) for the DVC
OPEN TMR Target
CLS TMR Target
Interlock
Confirm Close
Confirm Open
Security Lockup
3.
30 sec
30 sec
Yes or No
Yes or No (as required)
Yes or No (as required)
No
DVC links shall be as follows. Only those differing from the DVC
Input
@d
@e
@g
@h
@k
@n
A
B
C
Source
Eng Zero
Eng Max
Units
CB/A
CB/B
open confirm CIB/DIB
close confirm CIB/DIB
*VALUE
0
1
AUTO OPN
*VALUE
0
1
AUTO CLS
*VALUE
0
1
MODE
linked to @k. The @k link forces the DVC to the passive (typically
closed) position if the signal is OFF. The DVC interlock can be
bypassed with a supervisor’s key. If applicable, a signal representing
all process shutdowns shall be linked to @j. The @j link forces the
DVC to the passive (typically closed) position if the signal is ON. The
DVC shutdown cannot be bypassed. If @k or @j links are used, they
shall be displayed on the faceplate.
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4.
For single acting spring return valves, the output from the DCS
energizes a 3-way (air supply port, air to actuator port, and vent port)
2-position (pressurize and vent) solenoid valve to move the ON/OFF
valve to its active position (typically open) and de-energizes the
solenoid valve to allow the spring to move the ON/OFF valve to its
passive position (typically closed). A single acting valve is FAIL
CLOSED (FC) if the spring forces it closed and is FAIL OPEN (FO) if
the spring forces it open. For double acting valves, the output from
the DCS energizes a 4-way (air supply port, air to one side of the
actuator port, air to the other side of the actuator port, and vent port
(5-way if both actuators have separate vent ports)) 2-position
(pressurize one side of the actuator / vent the other, and visa versa)
solenoid valve to move the ON/OFF valve to its active position and
de-energizes the solenoid valve to move the ON/OFF valve to its
passive position. A double acting valve equipped this way fails in the
PASSIVE position with loss of electrical signal and fails in LAST
POSITION with loss of instrument air pressure. The DCS output
signal for both types of ON/OFF valve must be latched ON to energize
the solenoid valve and latched OFF to de-energize the solenoid valve.
An alternate design for a double acting valve is to energize two
solenoid valves (one to move the ON/OFF valve to one position and
the other to move the ON/OFF valve to the other position) from two
opposite acting DCS output blocks. The ON/OFF valve with this
arrangement fails in LAST POSITION with loss of electrical signal or
loss of instrument air pressure.
5.
Logic step “a” shall be linked to the DCS open/close contact/discrete
output block(s) (COB/DOB). Step “a” of a DVC contains default logic
that latches step “a” ON to energize a solenoid valve and latches step
“a” OFF to de-energize a solenoid valve. For single acting valves and
for double acting valves fitted with a multi-port solenoid valve, the “a”
logic step shall be linked to one COB/DOB configured as Contact
Type “NO”, Output Hold “None”, and use a NO opto. For double
acting valves fitted with a solenoid valve on each side of the actuator,
the “a” logic step shall be linked to two COB/DOB’s, one configured as
Contact Type “NO” and one configured as contact type “NC”, both
configured as Output Hold “None”, and both using NO optos. The “a”
output step cannot be turned ON if an interlock or shutdown is active.
Revision: 5
6.
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The table below summarizes the open/close output command
configuration for DVC’s.
Single acting valve or double acting valve fitted with a multi-port
solenoid valve
Single acting
Double acting
Open/Close
Open/Close
COB/DOB
COB/DOB
Block Input
DVC Step “a”
DVC Step “a”
Block Output
solenoid valve
solenoid valve
Contact Type
NO
NO
Output Hold
None
None
Hold Time
------------Opto Type
NO
NO
Opto Fail State
Passive (spring return)
Passive (*)
Inst Air Fail State
Passive (spring return)
Last position
* the position the ON/OFF valve moves towards when the solenoid
valve is de-energized.
Double acting valve fitted with a solenoid valve on each side of the
actuator
Position 1
Position 2
COB/DOB
COB/DOB
Block Input
DVC Step “a”
DVC Step “a”
Block Output
solenoid valve 1
solenoid valve 2
Contact Type
NO
NC
Output Hold
None
None
Hold Time
------------Opto Type
NO
NO
Opto Fail State
Last position
Last position
Inst Air Fail State
Last position
Last position
7.
ON/OFF valves should be installed with an open confirm, close
confirm, or both. Open confirms shall be linked to discrete input @g
and close confirms shall be linked to discrete input @h. The table
below summarizes the confirm configuration for DVC’s.
Revision: 5
Document #: CS17130
Block Input
Block Output
Field Contact
Filter Type
Opto Type
Opto Fail State
Open
CIB/DIB
Open confirm switch
DVC link @g
NO
None
NO
Not Open
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Close
CIB/DIB
Close confirm switch
DVC link @h
NO
None
NO
Not Closed
8.
9.
@e discrete inputs (see above), which are the Auto open and Auto
Close input registers for DVC Control Blocks. This configuration
allows a single discrete input (@n) to toggle the DVC from Auto Open
to Auto Close. If the @n input alone acts on the Auto Open/Close
On=>A=@n; B=~@n
Off=>A=@n; B=~@n
If other data besides the @n input acts on the Auto Open/Close
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command or if actions are required when the Auto Open/Close
On=>A=n; B=~n
Off=>A=n; B=~n
Open/Close command, and perhaps actions that occur when the Auto
Open/Close command is changed.
10.
Logic step “b” can be used to lock valves that are not actuated
automatically (only actuated by the DCS console keyboard, not by
another DCS device or batch task) in OPERATOR mode. For valves
On=> setmode 1
Off=> setmode 1
11.
Logic step “c” can be used to change the Control Block mode based
on a value written to it from a batch task. If batch tasks are used to
follows:
c=> C>0
Rise=> setmode C
On=> C=0
to step p.
12.
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On=> A.u=R.u
Off=> A.u=R.u
For example, with A.u=R.u true in Control Block XV-100, discrete
input @e is linked to another Control Block or graphic object by linking
XV-100/A/e (or in some cases XV-100.A.e).
13.
fails (e.g., the valve confirm state fails to agree with the output
command within the prescribed time after a state change, or the open
or close confirm is lost). This should trip a critical alarm. Logic step
“e” shall be configured as follows:
Rpt> Crit
When> On
14.
Auto Open/Close command or if actions are required when the Auto
Open/Close command is changed. Below are examples of how logic
n=> @n
Rise=> setmode 2
Fall=> setmode 2
or
n=> @n&(L<25)
15.
interlock or shutdown becomes active. Logic step “o” shall be
configured as follows:
o=> (@j|~@k)&@g
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Rpt> Crit
When> Rise
B.
Configuration of Fail Open Valves
1.
The standard RS3 DVC control block is configured for a fail closed
(FC) valve. In order to provide the proper valve action and display for
fail open (FO) valves, the following must be changed:



Reverse message pairs assigned to discrete inputs used for
Manual Open/Close and Auto Open/Close.
Reverse links assigned to discrete inputs used for Open and
Close confirms. Message pairs follow the reversed links.
Reverse message pairs assigned to discrete outputs used for
output commands to Open and Close the valve.
The FO DVC controller will then act as follows:



Logic step “a” remains the step linked to the output COB/DOB,
but for FO valves step “a” energizes the solenoid valve to
CLOSE the ON/OFF valve.
Pressing the ON button on the DCS console keyboard when
the cursor is on a FO DVC is a command to place the valve in
the active state, that is, to CLOSE the valve.
Active interlocks and shutdowns force a FO valve to its
passive state, that is, to de-energize the solenoid valve to
OPEN the ON/OFF valve.
These changes are summarized below.
2.
The table below shows the reversed message pairs assigned to
discrete inputs used for Manual Open/Close and Auto Open/Close
and for discrete outputs used for output commands to Open and
Close the valve:
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Input
Register
@a
@b
@d
@e
@g
@h
Standard DVC
(fail closed)
[Op] Open
[Op] Close
[Auto] Open
[Auto] Close
Open
Close
Fail Open Valve
[Op] Close
[Op] Open
[Auto] Close
[Auto] Open
Close
Open
Output
Register
Step “a”
Step “b”
Open
Close
Close
Open
Where
[Op] means “this is the discrete input for the Operator
mode command” – the text inside the brackets is not
part of the message pair text.
[Auto] means “this is the discrete input for the Auto
mode command” – the text inside the brackets is not
part of the message pair text.
Open means “standard message pair *8 (OPEN = true,
open = false)”
Close means “standard message pair *9 (CLOSE =
true, close = false)”
With the registers displayed in standard order on the faceplate and
the message pairs reversed, the faceplate for FO valves will display
Start and Stop words (inputs and outputs) in reverse order compared
to a standard FC valve. This highlights to the operator that the valve
is reverse acting.
3.
Logic step “a” shall be linked to the DCS open/close COB/DOB. Step
“a” of a DVC contains default logic that latches step “a” ON to
energize a solenoid valve and latches step “a” OFF to de-energize a
solenoid valve. The COB/DOB shall be configured as Contact Type
“NO”, Output Hold “None”, and use a NO opto. The “a” output step
cannot be turned ON if an interlock or shutdown is active, so FO
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valves OPEN when an interlock or shutdown is active.
4.
The table below summarizes the open/close output command
configuration for FO DVC’s.
Block Input
Block Output
Contact Type
Output Hold
Hold Time
Opto Type
Opto Fail State
Inst Air Fail State
5.
Except for the switching the links associated with open and close
confirms, the CIB/DIB configuration is the same as for FC valves. The
table below summarizes the confirm configuration for FO DVC’s.
Block Input
Block Output
Field Contact
Filter Type
Opto Type
Opto Fail State
6.
2.05
Open/Close
COB/DOB
DVC Step “a”
solenoid valve
NO
None
------NO
Open
Open
Open
CIB/DIB
Open confirm switch
DVC link @h
NO
None
NO
Not Open
Close
CIB/DIB
Close confirm switch
DVC link @g
NO
None
NO
Not Closed
There are no changes in the configuration of the logic steps
(conditions and actions) – configure the same as for FC valves.
Interlocks/Shutdowns
A.
General
1.
A signal representing all process interlocks shall be linked to @k of
the Control Block of the device affected by the interlock. The @k link
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forces the DMC or DVC to the passive (typically stopped or closed)
state if the signal is OFF. The Control Block interlock can be
bypassed with a supervisor’s key. A signal representing all process
shutdowns shall be linked to @j of the Control Block of the device
affected by the shutdown. The @j link forces the DMC or DVC to the
passive (typically stopped or closed) state if the signal is ON. The
Control Block shutdown cannot be bypassed. If @k or @j links are
used, they shall be displayed on the faceplate.
Both interlock (@k) and shutdown (@j) flags force a Control Block to
the passive state independent of Control Block mode. The Shutdown
flag is more suited to safety trips because it cannot be bypassed with
a supervisor’s key.
2.
When an interlock or shutdown is based on a continuous signal, the
trip point should be either the Critical High or Critical Low Alarm of the
Control Block measuring the continuous signal. A logic step should
then be configured in this Control Block referencing the Critical High
or Critical Low system flag, and that logic step then linked to the
interlock or shutdown Control Block link (@k or @j) of the device
affected by the interlock/shutdown.
This method assures that
changes to Critical Alarm values are reflected in interlock/shutdown
trip points. The Critical High system flag for the A register is A.s.p and
the Critical Low system flag for the A register is A.s.o.
3.
Interlocks/Shutdowns comprising multiple inputs or complex logic
shall be configured in a separate DISCRETE Control Block. Simple
interlock logic requiring only one input does not require a Control
Block. For example, if a high level alarm should shut down a pump,
link a logic step from the high level Control Block (containing
reference to the high level switch discrete input) to the @j or @k link
of the pump. However, if the shutdown depends on level and
pressure, logic steps from each Control Block should link to a
separate interlock Control Block where multiple inputs are combined
in a logic step to one output and this output is then linked to the @j or
@k link of the pump. The Interlock Control Block can have multiple
discrete and analog inputs and can contain multiple interlocks
configured in separate logic steps to link to multiple device Control
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Blocks. Provide comments in logic steps to describe the interlock
logic and what device it affects. The interlock block shall be tagged
according to the convention outlined in Part 1.01, Section B.
4.
Do not alarm each logic step containing inputs for interlocks. The
device itself will alarm if any interlock or shutdown becomes active.
5.
Resets may be required for interlock/shutdown signals, where a
button must be pressed from the console keyboard in order to clear
an interlock/shutdown that has tripped. An example where a reset
may be advised is on an interlock to a pump that may be started in
Auto mode (from either another Control Block or from a Batch Task).
Typically the Auto Start is a latched signal that stays on even if an
interlock signal causes the pump to stop. Without a reset on the
interlock signal, the pump will restart immediately after the interlock
signal clears. The examples below compare interlock logic with and
without a Reset. The Reset button (@o) is a momentary ON discrete
input.
Interlock logic without Reset
a=> @b|@c
Set=>
Clear=>
Interlock logic with Reset
a=>
Set=> @b|@c
Clear=> ~(@b|@c)&@o
6.
Every input affecting interlock/shutdown signals shall be displayed in
a way that clearly indicates what signal(s) is interlocking a device
OFF. This can be done using faceplates or graphic displays. Graphic
displays are the recommended method, using the following
guidelines:

Each input affecting the interlock shall be assigned to a single
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




B.
C.
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logic step, the logic step turning ON when the interlock is
active. A User Message Pair is assigned to that logic step that
shows ALARM in red when true, OK in green when false.
Configure each logic step with or without Reset, as required.
Reserve the @o discrete input configured as a momentary ON
to be used as the Reset button.
Combine the individual logic steps as required into a single
logic step. Reverse this signal if necessary and link this to the
@j or @k link of the device Control Block.
Create an interlock detail graphic for each device’s interlocks
that displays the message pair (ALARM or OK) from each
logic step containing interlock inputs. Use text to clearly label
each message pair.
Include a Reset button link on the interlock detail display.
Provide on the main graphic near the device affected by an
interlock a link to the interlock detail graphic.
Motor Interlocks
1.
Motor driven device interlocks and shutdowns shall always drive the
motor OFF.
2.
Motor driven devices are controlled with a DMC Control Block and the
STOP logic is configured to latch the DCS STOP output OFF if any
interlock is active, preventing the device from being started even from
a field start button. See Part 2.03, Section B.
3.
Resets should be considered for interlocks on motor-driven devices to
prevent automatic restart after interlocks clear under certain
conditions. See Part 2.05, Section A above.
Discrete Valve Interlocks
1.
Discrete valve interlocks and shutdowns shall always drive the valve
to its passive state.
2.
Resets should be considered for interlocks on discrete valves to
prevent automatic repositioning of the valve after interlocks clear
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under certain conditions. See Part 2.05, Section A above.
D.
Modulating Valves
1.
Interlocking a modulating valve should never be the only safeguard
against an unsafe condition. Complete shutoff cannot be guaranteed.
2.
Interlocks can drive a modulating valve to any required % open
position. Typically modulating valves are driven to the failed position
(0% signal). In addition to forcing output Q, the mode must be forced
to MANUAL. See examples below.
Interlock driving FC valve closed
a=> @b|@c
Set=> setmode 1; Q=0
Interlock logic driving FC valve open
a=> @b|@c
Set=> setmode 1; Q=1
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A.1 AIB I/O Block
A.2 AOB I/O Block
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A.3 CIB/DIB I/O Block
A.4 COB/DOB I/O Block
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A.5 TIB Block
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A.6 Manual Block
This example illustrates an analog monitoring block, where only the
process variable 'A" is displayed on the faceplate. The logic step "k" is
used when a process graphic color change is needed due to a high or low
critical alarm becoming active.
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A.7 PID Control Loop
This example illustrates an analog Control Block. The logic step "k" is used
when a process graphic color change is needed due to a high or low critical
alarm becoming active.
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A.8 Cascade Control Loop
This example illustrates a cascade control loop. The Master Control Loop
output has a high limit restriction.
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A.9 Ratio Control Loop
This example illustrates a ratio control loop. The Ratio is operator enterable and
is displayed on the Discrete Faceplate. The Ratio Limits are set on the
Continuous Faceplate. Input "G" shows the calculated actual ratio of the two
flows. Logic step "a" turns ON when the block is in Remote Mode (Ratio
Control), and this step is used by the process graphic containing the ratio control
loop.
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A.10 Stack Totalizer
This example illustrates a stack flow totalizer. The Discrete Faceplate has been
customized to show today's total, the last three previous totals, an operator-reset
switch for the totalizer, and the current flow rate. On the Continuous Faceplate,
the Periodic Reset is configured to reset the totalizer every day at 7:30 AM and
the Low Cutoff is set at 5% of the flow range being totalized.
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A.11 Group 1- START/STOP Motor
This example illustrates a motor control configuration for an agitator with DCS
START/STOP capability. This motor uses a momentary start COB/DOB and
continuous stop COB/DOB. There is run confirm indication only. This is the
standard motor controller, which is shown in the motor control schematic at the
end of this Appendix.
Logic step “c” is configured to change the mode of the motor from a batch script.
This is accomplished by writing a value to continuous register C from a batch
script. Discrete input @n is configured as *Value and is used to start or stop the
motor from a batch script when the Control Block is in auto mode. Logic step “n”
receives the input from @n if actions accompany auto start or stop, and logic
step ”a” sets the value of continuous registers A and B to ~@n and @n
respectively. Continuous registers A and B are then linked to the auto start and
stop discrete inputs @d and @e respectively.
A field start/stop panel (or on MCC) retains equal priority with DCS unless there
is an interlock condition.
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A.12 Group 2 - START/STOP Motor
This example illustrates a motor control configuration for an agitator with DCS
START/STOP capability. This type of motor control uses a single COB/DOB for
start and stop commands and typically has a hand/off/auto field switch. A single
CIB/DIB is used for motor status. The motor controller configuration is exactly
the same as Group 1 controllers except step “m” is not configured (left blank and
references no output block) and the COB/DOB output block that step “a” links to
is latching (not pulse). See the Group 1 motor screens above (except leave step
“m” blank). Below is the latching COB/DOB. No further field installations of this
set-up are permitted.
The agitator can be started and stopped by a batch script as with the Group 1
motor.
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A.13 Fail-Closed Valve
This example illustrates a fail-closed ON/OFF valve controller.
Logic step “c” is configured to change the mode of the motor from a batch script.
This is accomplished by writing a value to continuos register C from a batch
script. Discrete input @n is configured as *Value and is used to open or close
the valve from a batch script when the Control Block is in auto mode. Logic step
“n” receives the input from @n if actions accompany auto open or close, and
logic step “a” sets the value of continuous registers A and B to ~@n and @n
respectively. Continuous registers A and B are then linked to the auto open and
close discrete inputs @d and @e respectively.
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A.14 Fail-Open Valve
This example illustrates a fail-open ON/OFF valve controller.
The standard RS3 DVC control block is configured for a fail closed (FC) valve. In
order to provide the proper valve action and display for fail open (FO) valves, the
following must be changed:

Reverse message pairs assigned to discrete inputs used for Manual
Open/Close and Auto Open/Close.

Reverse links assigned to discrete inputs used for Open and Close
confirms. Message pairs follow the reversed links.

Reverse message pairs assigned to discrete outputs used for output
commands to Open and Close the valve.
The message pairs and assignments for the inputs and logic steps are reversed
in comparison to the Discrete Valve Control (Fail-Close) example.
Logic step “a” remains the step linked to the output COB/DOB.
All logic steps are configured the same as for fail-closed valve controllers.
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A.15 Motor Control Schematic
(Drawing SD-00-0261)
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Revision History
Revision
Date
Page
1
01/01/2000
All
2
04/10/2006
All
3
09/16/2009
All
4
02/21/2013
All
5
04/05/2016
All
Description
Changed from Henkel to Cognis
Updated Header and added Revision
History
Reviewed – no changes made
Updated BASF Header and added
Approval Section; Reviewed, no
changes made to content.
No changes
Initiator
Karen Whittington
Karen Whittington
Jim Russell
Jonathan Shute
J. Shute
Approvals
Prepared By: __________________________________________ Date: ________________
Process Control Engineer
Approved By: __________________________________________ Date: ________________
TES Manager

RS3 DCS Controller Configuration

Transcription

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