Light Curtain Installation

Transcription

Safety Light Curtains
Light Curtain Installation
I
Two and Three-Box Systems
Note: Omron STI safety light curtains are available in two different system configurations. The first configuration is referred to as a
"two-box" system. This means that the transmitter and receiver do
not connect to a central controller. All light curtain inputs and outputs are made at the receiver. In most cases, the transmitter simply
requires power to be fully functional. The transmitter and receiver
are not physically connected but are optically synchronized via
one of the infrared beams. The second configuration uses cables to
connect the transmitter and receiver to a central controller or "third
box". This controller contains control reliable circuitry and serves
as a convenient central location for all light curtain inputs and
outputs.
MiniSafe® MS4600
MiniSafe® MS4700
The MiniSafe MS4600 Light Curtain is a
The MiniSafe MS4700 Light Curtain is a
“two-box” light curtain .
“three-box” light curtain.
! WARNING: The information provided in this section is general in nature and is written to provide
an overview of the safety light curtain installation process. A safety light curtain should only be installed,
checked out, and maintained by a qualified person. A qualified person is defined as “an individual who
understands, is trained on, and demonstrates competence with the construction, operation or maintenance of the
machinery and the hazards involved.” (ANSI/PMMI B155.1-2006)
Omron Scientific Technologies, Inc.
USA Tel. 1/888/510-4357 Canada Tel. 1/866/986-6766
For the Latest Information
On the Internet: www.sti.com or www.omron.ca
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engineering guide
t is important that the user be
familiar with the installation
requirements, safe mounting
distance, controls and features
before using a safety light curtain.
Omron STI has found that light
curtain installation is most easily
accomplished if it broken down
into discrete steps. These steps
include:
1. Understanding the usage
requirements for a safety light
curtain.
2. Calculating the minimum safe
distance.
3. Physically mounting the light
curtain.
4. Preparation of the control
enclosure.
5. Configuring the features of the
light curtain.
6. Connection of power and
termination of outputs.
7. Application of power and
safety light curtain alignment.
8. Testing of the safety light
curtain for proper operation.
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engineering guide
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Step 1. Usage
Requirements
A safety light curtain is a safety
device, designed to protect operators and other personnel working
around a potentially dangerous
machine. Before installing or
using a safety light curtain the following requirements must be met:
■ The machine on which a safety
light curtain is installed must
be capable of stopping motion anywhere in its stroke or
cycle. For example, do not use
a light curtain on a power press
with a full-revolution clutch.
■ Do not use a light curtain on
any device with an inconsistent
stopping time or inadequate
control devices or mechanisms.
■ Do not use a light curtain where
the environment; such as severe
smoke, particulate matter or
corrosive chemicals; may degrade the efficiency of the light
curtain.
■ Be aware - light curtains do
not offer protection from flying
objects.
■ In any installation where the
light curtain is used as a safety
device, the employer has the
responsibility to ensure that all
applicable federal, state and
local government requirements
are satisfied. In addition, the
employer must ensure that all
machine operators, die setters,
maintenance personnel, electricians, supervisors, foremen, etc.
are familiar with and understand all instructions regarding
the proper use of the light
curtain, the machinery on which
it is installed and the appropriate safety regulations.
■ All safety-related machine control circuit elements, including
pneumatic, electric, or hydraulic
controls must be control reliable.
See Theory of Operation and
Terminology for a definition of
control reliable.
■ Any power press which uses
a light curtain must meet the
requirements and inspection
procedures of OSHA regulation 1910.217, ANSI standards
B11.1 and B11.19, plus any
other applicable state and local
regulations. All other machinery
or equipment must meet OSHA
standard 1910.212 on general
machine guarding plus any
other applicable regulations,
codes and standards.
■ Do not use a light curtain as a
lockout device to satisfy the US
Federal OSHA lockout/tagout
requirements.
■ Additional guarding, such as
mechanical guards, may be
required if the light curtain does
not protect all areas of entry to
the point of operation hazard.
■ All brakes and other stopping
mechanisms and controls must
be inspected regularly to ensure
proper working order. If the stop
mechanisms and associate controls are not working properly,
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the machine may not stop safely
even though the light curtain is
functioning properly.
■ The test procedure must be performed at installation and after
any maintenance, adjustment,
repair or modification to the
light curtain or the machine. In
addition, the tests must also be
performed after Channel Select
or Floating Blanking is enabled
or disabled. Testing ensures
that the light curtain and the
machine control system work
properly to stop the machine.
A sample test procedure is
included in this section.
■ All procedures in the installation and operating manual must
be followed for proper operation
of the light curtain.
The enforcement of these requirements is beyond Omron STI’s
control. The employer has the sole
responsibility to follow the preceding requirements and any other
procedures, conditions and requirements specific to your machinery.
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What is the Minimum Safe
Distance?
One of the most important
criteria for proper use of a safety
light curtain for machine guarding involves the minimum safe
distance. A light curtain must be
mounted far enough away from
the point of hazardous operation
so the machine will stop before
the operator’s hand or other body
part can reach this hazardous
point. The minimum safe distance,
is based on the stopping time of
your machine. It is a calculated
number based on a formula.
The purpose of this calculation
is best described by ANSI B11.192003 (6.2), “When required by this
standard, the guard or safeguarding device shall be located at a
distance from its associated hazard
such that individuals cannot reach
the hazard before cessation of
hazardous motion (or situation).”
Regardless of the calculated
distance, OSHA requires that a
light curtain never be mounted
closer to the pinch point than the
equivalent distance allowed for a
physical guard. This is outlined
by OSHA Table 0-10 in OSHA
1910.217. Do not use the Table
0-10 distance for your application
- you must perform the calculations to find the minimum safe
distance. The OSHA Table 0-10
distances depend on the light curtain minimum object resolution.
Two different formulas are
used to calculate the safe distance. One formula is outlined
in OSHA 1910.217 and applies
to the guarding of mechanical
power presses, but should serve
as a guide for other machine
applications.
The American National Standards Institute (ANSI) standard
B11.19-2003 uses a newer
formula which takes into consideration more factors in calculating
the minimum safe distance than
the OSHA formula. Omron STI
suggests using the ANSI formula
and presents it here.
If your installation uses a
horizontal mounting of the light
curtain, please skip ahead a few
pages to that section.
! WARNING: The proper
calculation of the safety distance
is an important step in the installation. Never install a safety light
curtain at any convenient locaFig. 4.1 Minimum Safe Distance
light curtain
Step 2. Calculating the
Minimum Safe Distance
Ds
Ds is the minimum safe distance between the light
curtain sensing field and the point of operation
hazard (pinch point).
tion without regard to the safety
distance. If the safety light curtain
is mounted too close to the point
of operation hazard, the machine
may not stop in time to prevent an
operator injury.
ANSI Minimum
Safe Distance Formula
The basis for the following
information is ANSI standard
B11.19-2003.
The ANSI formula consists of:
Ds = K (Ts + Tc + Tr + Tspm) + Dpf
Where:
Ds = The minimum safe distance, in inches, between the
light curtain sensing field and the
nearest point of operation hazard.
K = The maximum speed at
which an individual can approach
the hazard, expressed in inches
per second.
To quote ANSI B11.19-2003,
“The factor K is the speed constant
and includes hand and body movements of an individual approaching a hazard area. The following
factors should be considered when
determining K:
a) Hand and arm movement;
b) Twisting of the body or shoulder,
or bending at the waist;
c) Walking or running.
One of the accepted values for
K is the hand speed constant (it is
usually considered as the horizontal motion of the hand and arm
while seated). Its common value
is 63 in./s although other values
(typically higher) are also used.
The hand speed constant does not
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Fig. 4.2a Correct Light Curtain Installation Example
Ds
Light Curtain
Hazard Zone
Supplemental
Guarding
Example
Mechanical
Barrier
Fig. 4.2b Correct Light Curtain Installation Examples
light curtain
NOTE:Additional supplemental guarding is required where unprotected entry to the hazard zone is accessible, such as along the sides and rear of the machine. A mechanical barrier should be used to prevent
personnel from standing between the light curtain and the machine. These drawings are for illustrative
purposes only. Your installation may differ from this example.
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light curtain
include other body movements,
which can affect the actual approach speed. Consideration of the
above factors should be included
when determining the speed
constant for a given application.”
Ts = The total time that it takes,
in seconds, for the hazardous motion to stop, or for the hazardous
portion of the machine cycle to
be completed. Note that different
machine types have different stopping methods and mechanisms.
Informative Annex D of ANSI
B11.19-2003 contains excellent
information on these considerations and factors.
Tc = The response time, in
seconds of the machine control
circuit to activate the machine’s
brake.
NOTE: Ts + Tc are usually
measured together by a stopping
performance monitor.
Tr = The response time, in
seconds, of the safety mat system.
This is provided in the installation
manual.
Tspm = The additional stopping
time, in seconds, allowed by the
stopping performance monitor
before it detects stop time deterioration. A stopping performance
monitor will halt the machine
when the stop time of the machinery exceeds the set limit. This
indicates that excessive brake
wear has occurred.
What should you do if your
machine does not have a stopping performance monitor? Add a
percentage increase factor to the
light curtain
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Fig. 4.3 Depth Penetration Factor
Object Sensitivity (S)
2.0 (50.8)
1.5 (38.1)
1.0 (25.4)
0.5 (12.7)
0.0
0.0
1.0
2.0
3.0
(25.4) (50.8) (76.2)
4.0
(102)
5.0
(127)
6.0
(152)
7.0
(178)
8.0 in
(203) (mm)
Depth Penetration factor ( Dpf )
This material is reproduced with permission from American National Standard B11.1-1988 - Mechanical Power Presses - Safety Requirements for Construction, Care and Use, (figure 2), copyright 1988 by
the American National Standards Institute. Copies of this standard may be purchased from the American
National Standards Institute at 11 West 42nd Street, New York, NY 10036.
Table 4.2 Omron STI Light Curtains Depth Penetration Factor
S (mm)
S (in.)
Dpf (mm)
MC/MS 4700-12
Model Series
12
0.47
17
Dpf (in.)
0.7
MC/MS 4700-14
14
0.55
24
0.9
1.75
MC/MS 4700-20
20
0.8
44
MC/MS 4700-30
30
1.2
78
3.1
MS/MG 4600-14
14
0.6
24
0.9
MS/MG 4600-20
19
0.75
41
1.6
MS/MG 4600-30
30
1.18
78
3.1
OF/MG 4600-50
53
2.1
131
5.2
MS/FS 4300
20
0.8
44
1.7
MS 4400
25
1.0
61
2.4
MC/MCF 4200
20
0.8
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1.8
measured stop time (Ts + Tc) to
allow for braking system wear. For
example, stopping performance
monitors usually add an extra
20% to the measured stop time.
We recommends that you contact
the manufacturer of your machine
for guidance in selecting a percentage increase factor.
Dpf = The added distance, in
inches, due to the depth penetration factor from figure 4.3 or table
4.2. This is related to the minimum object sensitivity of the light
curtain and how far an object can
move through the sensing field
before the light curtain reacts. By
know the minimum object resolution, S, of the light curtain, Dpf
is read directly from figure 4.3 or
table 4.2.
This table assumes that Channel Select or Floating Blanking is
not in use. If Channel Select or
Floating Blanking are active, their
effect must be considered in the
calculation of Dpf. This effect is
explained in the section “Channel
Select and Floating Blanking.”
Additionally, please note that
the Dpf values provided in this
section are for safety light curtains
which are installed vertically. For
horizontal or ground level mounting schemes, refer to the example
given later in this section. For
safety light curtains with a minimum object sensitivity greater
than 2.5 inches, please refer to
Annex D of ANSI B11.19-2003.
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in (mm)
2.5 (63.5)
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Example 1. ANSI Safety
Distance Calculation with
Brake Monitor
Presume a mechanical press
has a stopping time (Ts + Tc) of
0.200 seconds. This includes
the response time of both the
press brake mechanism and the
control circuits. The stop time
performance monitor is set for
0.240 seconds. The response
time of a MicroSafe MC4700-20
(solid-state output version) with
a protected height of 24 in. (600
mm) is 10 mS (0.010 s).
Determine Tspm and Dpf. From
the stopping performance monitor
set point:
Tspm = stopping time
performance monitor set
point - (Ts + Tc)
Tspm = 0.240 sec. - 0.200 sec.
Tspm = 0.040 sec.
A MicroSafe MC4700 has a
minimum object sensitivity (S) of
0.80 in. (20 mm).
From figure 4.3, the depth penetration factor, Dpf, is 1.7 inches
(44 mm).
Now, everything needed is
available. The formula is:
Ds = K x (Ts + Tc + Tr + Tspm) + Dpf
Substituting our values:
Ds = 63 in./sec. x (0.200 sec. +
0.010 sec. + 0.040 sec.) + 1.7 in.
Add the values in the parentheses first:
Ds = 63 in/sec. x (0.250 sec.) +
1.7 in.
Multiply the result in parentheses by 63:
Ds = 15.75 in. + 1.7 in.
Add the results:
Ds = 17.45 in. (450 mm)
Thus, in this example, the light
curtain must be mounted greater
than 17.45 in. (450 mm) from the
pinch point when measured to
the center of the MicroSafe’s front
surface.
Read the section on channel
select and floating blanking to see
their effect on this example.
EN 999 Minimum
Safe Distance Formula
Manufacturers planning to sell
their products into the European
market should be aware that there
is a different mounting formula
for presence sensing devices offered by standard EN 999. While
similar to the ANSI formula given
above, there are some subtle
differences.
The EN 999 formula (for a
normal approach) is explained
here:
S = K(t1 + t2) + C
Where:
S = the minimum safe distance
between the light curtain sensing
field and the point of operation
hazard in mm, but not less than
100 mm.
K = operator’s approach speed.
t1 = maximum stopping time of
the machine in seconds.
t2 = response time of the safety
light curtain in seconds.
C = additional safety distance
in mm, depending on the detection capability of the safety light
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curtain. The value of C is never
less than 0.
d = Minimum object resolution
(detection capability) of the light
curtain.
C = 8(d-14) where d≤40 mm
C = 850 mm where 40<d≤70 mm
The following identifies several
factors which affect the calculation of the safe distance formula:
First, the value of K, the operator’s approach speed, depends
on the application, the approach
direction, the minimum distance S
and the detection capability of the
light curtain, d. The values given
below are for a normal apæproach
direction.
S
K
d
100<S<500 mm 2000 mm/sec d≤40 mm
S>500 mm
1600 mm/sec d≤40 mm
S>850 mm
1600 mm/sec 40<d≤70 mm
In applications where S is calculated to be greater than 500 mm
using K= 2000 mm/sec, then the
formula must be recalculated
using K=1600 mm/sec. In this
case the minimum value of "S"
shall not be less than 500 mm.
■ Where light curtains are used
for machine initiation, then
K=2500 mm/sec. S must be
greater than 150 mm and the
minimum object resolution of
the safety light curtain must be
equal to or less than 30 mm.
■
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Horizontal Light Curtain
Installations
Certain applications may use
curtain to detect intrusion into a
hazardous area. For the purposes
of this section, the formula used
for horizontal mounting assumes
that the angle of approach by an
object through the sensing field is
less than 30°, as shown in figure
4.4. Applications where the angle
of approach is 30° or greater to
the sensing field should use the
ANSI formula (discussed earlier).
The following discussion is
based on material presented in
informative Annex D of ANSI
standard B11.19-2003.
The safe mounting distance
is measured from the point of
operation hazard to the sensing
field farthest away, as shown in
figure 4.4.
Figure 4.4
< 30°
light
curta
in
intrusion
Approach
h
Ds
Example — Horizontal Light
Curtain Installations
An automated machine has
a stop time as specified by the
manufacturer of 0.125 (Ts + Tc)
seconds. A MiniSafe MS4600
with a response time (Tr) of 0.025
seconds is mounted horizontally
in front of the operator load station. The hand speed constant K
is selected as 63 in./sec.
Ds = K x (Ts + Tc +Tr + Tspm ) + Dpf
(In this case Dpf is always 48
inches.)
Working the formula, we get:
Ds = 63 x (0.125 + 0.025 + 0) + 48
= 63 x (0.15) + 48
= 9.45 + 48
Ds = 57.45 inches (1459 mm)
floor
intrusion angle of approach less than 30° to the
sensing field.
To calculate Ds, use the ANSI
Safe Distance Formula, but use a
figure of 48 inches for Dpf.
This effectively means that
the minimum size of the sensing
field on a horizontally-mounted
light curtain is 48 inches when
no other forms of supplemental
guarding are used.
H, the allowable height of the
horizontal sensing field from the
floor varies and is dependent on
the minimum object resolution of
the safety light curtain. See Table
4.6.
The complete formula for
horizontal mounting is thus:
Ds = K x (Ts + Tc + Tr + Tspm ) + Dpf
Table 4.6
Allowable Sensing Field Heights in Inches (mm)
Ground Level Devices that Can Be Reached Over
(30 inches or Less)
ObjectMounting Height
SensitivityMinimumMaximum
< 2 (50)
0 39 (990)
2.5 (64)
7.5 (190) 39 (990)
3.0 (76)
15 (380) 39 (990)
3.5 (89)
22.5 (570) 39 (990)
4.0 (102)
30 (760) 39 (990)
4.25 (108)
33.75 (860) 39 (990)
4.6 (117)
39 (990) 39 (990)
Information from ANSI B11.19-2003 Annex D.
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Example 2. EN 999 Safety
Distance Calculation
An automated machine has a
stopping time of 0.100 seconds
as rated by the manufacturer.
The MicroSafe MC4700-20 safety
light curtain with solid-state safety
outputs and a 600 mm protected
height has a response time of 0.01
seconds and a detection capability
of 20 mm. The light curtain is not
used to initiate the machine:
S = K(t1 + t2) + C
Where:
K =2000 mm/sec.
t1 =0.100 sec.
t2 =0.01 sec.
C = 8(d-14); but C is never <0
d = 20 mm
S = 2000 mm/sec. (0.100 +
0.01 sec.) + 8(20-14)
S = 2000 mm (0.11) + 48
S = 268 mm
Remember that for K=2000
mm/sec., S must be greater that
100 mm and less than 500 mm.
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Fig. 4.5 Reflective Surface Interference
engineering guide
Approach direction
Approach direction
Beam Angle, a
interruption
transmitter
central beam
d
receiver
a
interruption
transmitter
light beam
interrupted
central beam
d
a
receiver
light beam
interrupted
reflection
reflective object
reflective Surface
Perimeter of danger area
Fig. 4.5a Example of correct mounting with proper alignment. The interruption is clearly detected. The reflective object is outside of the beam angle.
Fig. 4.5b Unsafe! Example of unsafe mounting. The interruption is not
detected because of reflection. The reflective object inside the beam angle.
Operating range, r
Sensing field
a
transmitter
receiver
a
interruption
d
transmitter
a
receiver
reflection
reflective Surface
reflective Surface
Perimeter of Danger Area
Fig. 4.5c Unsafe! Interruption is not detected because of reflection.
Reflective surfaces interference may also appear above and below the
sensing field.
Reflective Surface
Interference
A reflective surface adjacent to
the sensing field can deflect the
optical beam and may cause an
obstruction in the sensing field
not to be detected. (See fig. 4.5a,
b, c & d.). Reflective surfaces may
be part of the machine, mechanical guard or workpiece. Some
examples of reflective surfaces
may include shiny metal, glossy
paint, foil, plastic or other similar
material. A Test Procedure, such
Fig. 4.5d Worst case alignment shows minimum distance from reflective
surface, d, to one side of the beam center line.
as provided at the end of this section, must be used to test for this
condition.
Calculations can provide the installer with a means of anticipating reflective surface interference.
The light curtain must be installed
such that no reflective surfaces
are inside the beam angle of the
transmitter and receiver.
The minimum distance from
the sensing field to the reflective
surface, d, is calculated from the
formula. This assumes a worst
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Beam Angle, a
case condition where the transmitter and receiver are not in true
alignment, as indicated in Fig.
4.5d. The graph also requires the
Range Adjustment potentiometer
be properly set on those light
curtains which feature one.
The worst case distance, d, is
calculated from the formula:
d = R/2 (tan 2a) where a is the
angle of acceptance/divergence of
the safety light curtain and R is
the operating distance of the light
curtain installation.
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Now that the minimum safe
distance and reflective surface distance are known, the
safety light curtain may now
be mounted accordingly on the
machine, stands or other mounting fixtures.
Installation of Multiple Light
Curtain Units
Installations where two or more
light curtains are mounted on
machines in close proximity and
in alignment with each other,
precautions should be taken to
avoid one curtain interfering with
another. This can occur when
the receiver of one unit “sees”
machine 1
Thus, the center of the MicroSafe beam line must be placed
greater than 3.1 in. (79 mm) from
a reflective surface.
receiver
transmitter
Fig. 4.9 Multiple Light Curtain Installation
receiver
machine 2
transmitter
receiver
transmitter
Fig. 4.9a Not Recommended. This arrangement may be subject to interference between
the two light curtains.
receiver
If you prefer, the calculations are:
d = R/2 (tan 2a)
R = 6 ft., a = 2.5°, thus
d = 6/2 [tan 2 (2.5°)]
= 3 tan 5°
= 3 (0.0874)
= 0.26 ft. or 3.1 in. (79 mm)
Step 3. Physically Mounting
the Light Curtain
transmitter
Example — Reflective
Surface Interference
For example, a MicroSafe
MC4700 series is installed on an
assembly machine. The distance
between the receiver and transmitter is 6 ft. (1.8 m). What is the
minimum distance a reflective
object is permitted from the sensing field?
■
machine 1
machine 2
Fig. 4.9b Preferred. The suggested orientation. The receivers are mounted back to back.
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When planning for or evaluating an installation, consult the
appropriate operating manual to
determine the proper value for a.
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the transmitter of another. The
first unit will respond with a Red
Machine Stop condition.
Correction involves orienting
the light curtains such that the
transmitters or receivers are
mounted back-to-back to each
other as shown in figure 4.9a and
b. Contact Omron STI should you
need additional assistance.
Mounting Considerations
The transmitter and receiver
units must be securely mounted
at a distance from the pinch
point greater than minimum safe
distance. Other items to consider
when selecting a mounting location include:
1. If the light curtain does not
protect all access to the danger
point, the unprotected access must
be protected by other approved devices or supplemental guarding. An
operator must not be able to reach
around the light curtain in any
way to gain access to a hazardous
location of the machine or stand
between the machine and the light
curtain. A mechanical barrier in
front of the hazardous machine
area should be used to prevent
personnel from standing between
the light curtain and the machine.
(See fig. 4.2a & b).
2. Use caution when installing
any light curtain where the perimeter of the sensing field is adjacent
to a reflective surface, such as
shiny metal, foil, glossy paint,
plastic or other similar material. A
reflective surface can deflect the
Light Curtain Mounting Orientation
Figure 4.10a Correct
Figure 4.10b Incorrect
mirror
! WARNING: Unsafe! Omron STI Safety light curtains are not designed to be used in a mirror
bounce back mode. In this configuration, an object may not be reliably detected and may cause severe
operator injury.
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6. If you use a mirror, such as
a high quality Omron STI mirror,
in your installation, do not mount
the mirror in a retroreflective
orientation to the transmitter
and receiver units as depicted
in figure 4.10b. The transmitter
and receiver units must also be
installed parallel to and in line
with each other.
7. All cabling must be installed
and routed in accordance with
national and local electrical codes
and good workmanship practices.
Omron STI offers a variety of
mirrors, stands, mounting kits,
and cabling to simplify special
installation requirements.
■
■
Step 5. Configuring the
Features of the Light Curtain
Some light curtains contain
installation configuration options which allow flexibility for
your specific application needs.
Examples of installation selections include Operation Mode,
Auxiliary Relay Selection, MPCE
Monitoring, MTS, Exact Channel
Select, Floating Blanking, Restart
Interlock Mode and Range Selection. See your installation manual
or contact Omron STI for further
information.
Step 4. Preparation of the
Light Curtain
Input power, output machine
control, and, if used, remote function control must be connected
to the light curtain by means of
cables protected by conduit.
It is recommended that a clearance of approximately 4 inches
(100 mm) be maintained between
the receiver or transmitter cables
and any AC power lines. The
installer is responsible to use the
proper conduit cable fittings to
maintain the NEMA 4 and Ingress
Protection (IP) design integrity of
the light curtain control enclosure
(where applicable).
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engineering guide
optical beam and may cause an
obstruction in the sensing field
not to be detected. (See fig. 4.5).
Failure to correct this condition
can result in a severe operator
injury. Perform the Test Procedure
to test for this condition.
3. The sensing field of the
light curtain is marked on the
transmitter and receiver housings (see installation manual for
details). The area between the
housing bottom and beginning of
the sensing field is not protected.
Therefore, you should position
the light curtain so access to the
pinch point is only through the
marked sensing field or provide an
alternative means to prevent entry
to the hazardous location.
4. The transmitter, receiver and
cabling should be out of the way
of feedstock, raw material, parts,
tool and die changes, fork lifts,
etc.
5. Normally the transmitter and
receiver are mounted with the
cable end down and the plastic
bezels facing each other. To
install the units "upside down"
(cable ends up), both transmitter
and receiver units must be mounted with their cable connectors in
the same orientation. You may
also install the light curtain in a
horizontal plane, provided that
both units are oriented the same.
See figure 4.10a.
engineering guide
A
■
Step 6. Connection of
Power and Termination of
Outputs
! Warning: All electrical
connections must be made by
qualified personnel only and in
accordance with your local and
national electrical codes and
regulations.
Input Power Connections
Light curtains are generally
available in three input power
selections: 115 VAC, 230 VAC or
24 VDC. Check the product label
on the enclosure to verify the
voltage which may be used.
All light curtains must be connected to a good electrical ground.
It is recommended that the light
curtain be dedicated to its own
source of input power where possible. Also, do not connect other
devices to the internal power
supply of the light curtain.
Connecting to the Machine
Control Circuit
Light curtains may be connected
to your machine circuit in several
different configurations, depending on the machine controller
design and the light curtain model
selected. If you are evaluating an
existing light curtain installation,
certain models may not have all of
the features or output connection
options outlined in the following
sections. Please contact Omron
STI should you require assistance.
When deciding which method
is best for your application, keep
in mind the following important
points:
■ The safety light curtain must
be wired to your machine
control circuit at a point where
a stop signal from the light
curtain results in an immediate
halt during any point in the
machine’s cycle or stroke. If the
machine is a mechanical power
press, never connect a light
curtain to the top-stop circuit.
The press will be unable to stop
at any other point in its stroke.
■ Light curtains are general purpose safety devices and are not
designed for any specific type,
model or brand of machine.
■ All safety-related machine control circuit elements, including
pneumatic, electric or hydraulic
controls must be control
reliable.
■ Light curtains may not be used
as a tripping means to initiate
mechanical power press motion
except when used and installed
in total conformance with the
OSHA PSDI requirements of
1910.217(h).
■ You must always use both
safety outputs to connect to
your machine. Should one
output fail, the other is used to
stop the machine.
■ Omron STI recommends you
contact the machine manufacturer for advice and assistance
on the connection of any safety
device.
A54
If a PLC (programmable
logic controller) is used as the
machine controller, consult the
appropriate Omron STI light
curtain manual for proper connection information.
The installer must read and understand all instructions provided
in the installation manual provided with the safety light curtain.
■
! Warning: Contact the
protected machine manufacturer
for assistance on where to wire
the light curtain to your machine
control circuit. It is critical that the
light curtain be properly connected or it will not provide maximum
protection to the machine operators and could result in serious
injury. The machine control circuit
wiring is the sole responsibility of
the employer.
A
! WARNING: Perimeter
guarding installations must not
allow a machine or robot to restart
automatically. Use a reset switch
placed outside and within view of
the hazard area.
Restart Interlock Mode
Restart Interlock (Guard) Mode
allows the light curtain safety
outputs to remain in a de-energized state (latch condition) after
an object detected by the light
curtain is removed from the sensing field.
It may be desirable to employ
Restart Interlock Mode when a
light curtain is used in perimeter
guarding installations.
Restart Interlock and Start Interlock are two separate programming choices, so it is possible to
set the system to go to a machine
run operating condition when
power is applied and the sensing
field is clear but to latch whenever
a beam is blocked. Omron STI
recommends activating Start Interlock whenever Restart Interlock
is enabled.
Machine Primary
Control Elements (MPCE)
The monitoring of the machine
control elements is an important
part of a safety system installation. First, a definition of a
machine control element.
Redundant machine control
circuits must have two machine
primary control elements (MPCE).
These are defined by IEC Standards as “The electrically powered
element that directly controls the
normal operation of a machine
in such a way that it is the last
element (in time) to function when
machine operation is to be initiated
or arrested.” [IEC61496-1].
It is important to note that the
methods to arrest hazardous
machine motion will include
hydraulic, pneumatic, clutch and
mechanical braking systems.
Thus, there are several variations
of MPCEs. For example, your
MPCE may consist of relays,
contactors, solenoids or electromechanical valves.
The purpose of monitoring the
action of each MPCE is to make
sure it is responding correctly to
the light curtain’s safety outputs
and to detect any inconsistency
between the two MPCEs. Monitoring of the light curtain to machine
control interface is necessary to
detect a malfunction within the interface that would prevent a stop
signal from the light curtain from
reaching the machine controller.
This is required by OSHA for
control reliability of the machine
controller to safety device wiring.
If relays, the MPCE must use
captive contact type, machine
control relays to be effective for
the MPCE monitoring wiring.
A55
engineering guide
PERIMETER GUARDING
SPECIAL REQUIREMENTS
Perimeter guarding refers to installations where the light curtain
is generally positioned around the
outside perimeter of the machine
or robot to be guarded. This
could leave sufficient space for
an operator to stand between the
light curtain and the machine. A
curtain may prevent this.
For perimeter guarding installation, the guarded machine or
robot must be wired such that any
detected interruption of the sensing field will cause an immediate
stop of the hazardous motion. The
machine or robot must only be
restarted by actuation of a reset
switch. This reset switch must
be located outside the area of
hazardous motion and positioned
such that the hazardous area can
be observed by the switch operator. This would prevent a machine
from automatically restarting
once the obstruction is no longer
detected by the light curtain.
The emergency stop circuit
may possibly be used to interconnect a perimeter guard in certain
installations where an external
reset pushbutton or keyswitch is
used. Always contact the machine
manufacturer for advice and assistance on the connection of any
safety device.
engineering guide
A
Preferred connection
Method with relay
outputs
The following connection
scheme uses both safety output
relays to control the machine.
This is the preferred wiring
method.
Figure 4.11
The method to arrest hazardous
machine motion will vary depending on the type of machine.
Control methodologies include
hydraulic, pneumatic, clutch and
mechanical braking systems.
Thus, there are several variations of MPCEs, including relays,
contactors, solenoids and electromechanical valves.
PREFERRED CONNECTION DIAGRAM METHOD
Check unit for proper voltage requirements before powering up unit.
lcm Series shown. consult product manual for complete details.
line /
24 VDc
tB1
neutral /
0 VDc
System control voltage
If you are unsure of the proper
connection location to use for
your machine's control systems,
Omron STI recommends you
contact the machine manufacturer
for assistance.
This connection scheme requires a separate normally open
(NO) output from both relays
and proper wiring of the MPCE
monitoring connections.
A sample wiring diagram is
included in fig. 4.11. Consult your
light curtain’s Installation Manual
for specific connection terminals
corresponding to the sample wiring diagram.
One NO open contact from each
of two output relays are wired to
two MPCE, as shown in fig. 4.11.
tB2
arc suppressor
OSSD 1
1
mPce 1
mPce 1
mPce 2
arc suppressor
OSSD 2
1
mPce 2
machine control contacts
tB3
Auxiliary
notes:
1
mPce 1
tB7
mPce 1
1
mPce
2
3
2
2
no external power is to be applied to the
terminals of tB7.
3
the relay contacts of mPce1 and mPce2
must be force-guided.
1
StArt
2
2
A56
Arc or transient voltage suppression devices
should only be installed across the coils of
the machine control relays. never install arc
or transient voltage suppressors across the
contacts of the safety light curtain. failure of
the suppression in a short condition, across
the contacts, will result in an unsafe condition.
A
output relay. The NC contact is
obtained from the second output
relay. See figure 4.12.
This connection scheme requires a NC contact from one of
the output relays.
The MPCE Monitoring connection as indicated on fig. 4.12
should also be installed. Note
NORMALLY OPEN, NORMALLY CLOSED
MACHINE CONTROL CIRCUIT CONNECTION
Figure 4.12
Check unit for proper voltage requirements before powering up unit.
lcm Series shown. consult product manual for complete details.
line /
24 VDc
tB1
neutral /
0 VDc
OSSD 1
OSSD 2
tB3
Auxiliary
mPce 1
1
mPce
2
! Warning: Arc suppression
and transient voltage suppression
arc suppressor
devices should only be installed
1
across the coils
mPce 1
of the machine
mPce 1
mPce 2
control relays.
Never install these
arc suppressor
devices directly
machine control contacts
1
across the control
mPce 2
output contacts of
the light curtain.
An arc or transient
notes:
voltage suppres1 Arc or transient voltage suppression devices
sion device may
should only be installed across the coils of
the machine control relays. never install arc
fail with a short
or transient voltage suppressors across the
circuit and if
contacts of the safety light curtain. failure of
the suppression in a short condition, across
installed across
mPce 2
the contacts, will result in an unsafe condition.
the contacts, will
no external power is to be applied to the
result in an unsafe
3
2 terminals of tB7.
condition.
2
3
1
StArt
2
Using Arc Suppression
Devices
Users should use arc suppression devices, also called snubbers,
across the coils of the machine
control contactors when switching AC loads (transient voltage
suppressors are used for DC
loads). These devices may extend
relay contact life of equipment
connected to the machine control
circuit.
System control voltage
tB2
tB7
also that a NC contact on one
MPCE is wired in series with a
NO contact on the other. This is in
conjunction with the connection
wiring to the MPCEs.
2
the relay contacts of mPce1 and mPce2
must be force-guided. to activate mPce
monitoring, Jumper 2 on the main control
board needs to be installed in the on position.
A57
engineering guide
Normally Open,
Normally Closed
Machine Control Circuit
Connection with relay
outputs
Both safety output relays of the
light curtain are used for this connection scheme. One NO signal is
obtained by connecting to a safety
engineering guide
A
Connecting solid-state
outputs to an sti relay
module
scheme shows an MS4600 light
curtain with solid-state safety
outputs interfacing with an RM-1
relay module. The concept is
Figure 4.16
similar for other safety products
with solid-state safety outputs.
The RM-1 module provides the
user with two normally open (NO)
safety contacts and two normally
closed (NC) monitoring contacts.
The NO contacts are connected to
two force-guided relays, MPCE1
CONNECTING SOLID-STATE OUTPUTS TO AN STI RELAY MODULE
Power Supply
earth +24vdc 0vdc
ground
check unit for proper voltage requirements
before powering up unit
Shielded
cable
Start
mS4600 rcVr
gray
Start
OSSD 1
OSSD 2
Brown
Drain
White
Blue
rm-1
Yellow
Orange
Shield
monitor
Brown
Aux.
Output
42
Pink
mPce1
41
mPce2
32
cOntrOl
VOltAge
31
SUPreSSOr
24
mPce1
23
14
SUPreSSOr
13
Shield
mPce2
+24vdc
0vdc
WArning: Arc and transient voltage suppression devices
should only be installed across the coils of the machine control
relays. never install arc or transient voltage suppression devices
directly across the control output contacts of the safety light
curtain. A suppression device installed across the contacts may
fail with a short circuit and will result in an unsafe condition.
A58
machine
control
contacts
+24vdc
mS4600 Xmtr
White
OSSD 2
0vdc
mPce 1 mPce 2
Braid
OSSD 1
0vdc
mPce
mon.
Shielded
cable
Shielded cable
and MPCE2. A set of NO contacts
from each MPCE (in series)
should be used to control the
machine's hazardous motion. In
some control systems, the RM-1
can be used as the MPCE. Contact the machine manufacturer for
the specifications of the control
components.
MPCE monitoring is performed
on the final switching devices.
This consists of a set of NC contacts from MPCE1 and MPCE2
connected through the receiver's
MPCE line to 0 VDC. If no external MPCE devices are used, the
monitoring should be performed
on the resource module in use.
For more information, please
consult the appropriate operation
and installation manual.
no external voltage is to
be applied to terminals
mtS 1 or 2, mOn 1 or 2
Damage to unit will occur.
nOte: mPce1, mPce2
are two user-supplied
control relays with
forced-guided contacts.
A
concept is similar for other safety
products with solid-state safety
outputs.
The MS4600 receiver provides
the user with 2 PNP solid-state
safety outputs capable of sourcing
500 mA @ 24 VDC. These safety
outputs are directly connected
to the two force-guided relays,
MPCE1 and MPCE2. A set of
normally open contacts from each
MPCE (in series) should be used
to control the machine's hazardous motion.
MPCE monitoring is performed
on the final switching devices. It
consists of a series set of NC contacts from MPCE1 and MPCE2
tied through the
CONNECTING SOLID-STATE OUTPUTS TO TWO FORCE-GUIDED RELAYS
Figure 4.18
receiver's MPCE line
to 0 VDC.
check unit for proper voltage requirements
before powering up unit
Power Supply
In some control
systems, the PNP
earth
safety outputs can
ground +24vdc 0vdc
Shielded cable
mS4600 rcVr
be directly interfaced
Start
SUPreSSOr
gray
into a safety PLC.
Start
Contact the machine
mPce1
Yellow
manufacturer for the
OSSD 1
SUPreSSOr
specifications on the
Orange
PLC.
OSSD 2
mPce2
Brown
Drain
White
Shield
machine control
contacts
+24vdc
Blue
Aux.
Output
Pink
mPce
mon.
mPce 1 mPce 2
Shielded cable
0vdc
mPce1
mPce2
mS4600 Xmtr
Drain
White
Brown
WArning: Arc and transient voltage suppression devices
should only be installed across the coils of the machine control
relays. never install arc or transient voltage suppression devices
directly across the control output contacts of the safety light
curtain. A suppression device installed across the contacts may
fail with a short circuit and will result in an unsafe condition.
Shield
+24vdc
0vdc
no external voltage is to
be applied to terminals
mtS 1 or 2, mOn 1 or 2
Damage to unit will occur.
nOte: mPce1, mPce2
are two user-supplied
control relays with
forced-guided contacts.
A59
engineering guide
CONNECTING SOLID-STATE
OUTPUTS TO TWO FORCEGUIDED RELAYS
scheme shows a MS4600 light
curtain with solid-state safety
outputs directly driving two forceguided relays (MPCE). The
engineering guide
A
Using the MPCE Monitoring
Function
With the MPCE Monitoring
function active, if the MPCE
signal does not close within 300
milliseconds after the light curtain
enters a Red Beam Blocked state,
or open when the light curtain
returns to a Green Beam Clear
state, then the controller will Fault
into a lockout condition.
The wiring for the MPCE Monitoring feature is explained in your
light curtain Installation Manual.
MPCE Monitoring with an
Interposing Relay
In some machine controller
designs, the light curtain outputs
are connected to two interposing
or pilot duty relays. These relays,
in turn, drive the MPCE. The
monitoring function must monitor
the MPCE and not the interposing
relay.
■
Step 7. Application of
Power and Safety Light
Curtain Alignment
This step examines the procedures to align the light curtain and
adjust the operating range.
At this point, the transmitter and
receiver units have been loosely
installed and are approximately
aligned. All wiring – to the light
curtain transmitter and receiver
units, to primary power, and to the
machine control system – have
been installed. Power, both to the
light curtain and to the machine to
be controlled, is off.
This section is concerned with
the physical alignment of the
transmitter and receiver heads.
Proper setup and alignment is an
important part of the installation.
Short range systems reduce the
risk of interference between one
light curtain system and another
which may be located nearby.
Mirror Alignment Hints
If difficulty arises when using the
light curtain with Omron STI’s mirrors, try using the following steps:
1. The mirrors must be parallel
to the transmitter and receiver. If
not, the beams will not be reflected evenly to the next mirror or
to the receiver. Most light curtains
are equipped with Individual
Beam Indicators, these serve as
an alignment aid. If an indicator is
on, that beam is not in alignment
or is blocked.
2. Try looking from behind either
the transmitter or receiver to locate
an image of the corresponding unit
reflected in the mirror(s). Have an
assistant adjust the mirrors until
the other unit is reflected fully in
the mirror. Make sure the machinery is disabled before working in a
hazardous area!
■
Step 8. Checkout and Test
Procedures
Fig. 4.17 Using the Test Object
St
Ar
t
St
OP
Use the test object to
interrupt the sensing field
along the center, bottom, sides
and top of sensing field.
Alignment
! WARNING: Before operating
the machinery, always perform
the Test Procedure after any
adjustment to the Range Set
Jumper, Range Adjustment or
other maintenance, adjustment or
modification to the light curtain
or machine. Testing is critical to
verify the safe installation of the
light curtain. Failure to properly
test may result in serious injury to
personnel.
To align a safety light curtain,
please follow the procedure
outlined in the manual for your
model.
A60
Now your light curtain is
mounted, configured, aligned and
connected to your machinery. The
machine power is off.
The following initial checkout
procedure must be performed by
qualified personnel. A copy of the
checkout results should be kept
with the machine maintenance
and inspection records.
A typical Checkout Procedure
Log form and Test Procedure form
are shown on the following pages.

Light Curtain Installation

Transcription

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