Safety Light Curtains Light Curtain Installation Idownloads.deusm.com/designnews/1586-CTLRCwp060608x2.pdf · Note: Omron STI safety light curtains are available in two differ-ent

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Light Curtain Installation

! 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)

Two and Three-Box SystemsNote: Omron STI safety light curtains are available in two differ-

ent 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 out-puts 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.

It 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.

miniSafe® mS4600

The MiniSafe MS4600 Light Curtain is a

“two-box” light curtain .

miniSafe® mS4700

The MiniSafe MS4700 Light Curtain is a

“three-box” light curtain.

Safety Light Curtains

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■ Step 1. Usage Requirements

A safety light curtain is a safety device, designed to protect opera-tors and other personnel working around a potentially dangerous machine. Before installing or using a safety light curtain the fol-lowing requirements must be met:■ The machine on which a safety

light curtain is installed must be capable of stopping mo-tion 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 de-grade 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, electri-cians, supervisors, foremen, etc.

are familiar with and under-stand all instructions regarding the proper use of the light curtain, the machinery on which it is installed and the appropri-ate safety regulations.

■ All safety-related machine con-trol 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 regula-tion 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 con-trols are not working properly,

the machine may not stop safely even though the light curtain is functioning properly.

■ The test procedure must be per-formed 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 installa-tion and operating manual must be followed for proper operation of the light curtain.The enforcement of these require-

ments is beyond Omron STI’s control. The employer has the sole responsibility to follow the preced-ing requirements and any other procedures, conditions and require-ments specific to your machinery.


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■ Step 2. Calculating the Minimum Safe Distance

What is the Minimum Safe Distance?

One of the most important criteria for proper use of a safety light curtain for machine guard-ing 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 B11.19-2003 (6.2), “When required by this standard, the guard or safeguard-ing 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 calcula-tions to find the minimum safe distance. The OSHA Table 0-10 distances depend on the light cur-tain minimum object resolution.

Two different formulas are used to calculate the safe dis-tance. 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 Stan-dards Institute (ANSI) standard B11.19-2003 uses a newer formula which takes into consid-eration 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 instal-lation. Never install a safety light curtain at any convenient loca-

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 dis-

tance, 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 move-ments of an individual approach-ing 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 horizon-tal 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

ligh

t cur

tain

DsDs is the minimum safe distance between the light curtain sensing field and the point of operation hazard (pinch point).

Fig. 4.1 Minimum Safe Distance


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Fig. 4.2a Correct Light Curtain Installation Example

Fig. 4.2b Correct Light Curtain Installation Examples

NOTE: Additional supplemental guarding is required where unprotected entry to the hazard zone is acces-sible, 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.

MechanicalBarrier

Ligh

t Cur

tain

Ds

SupplementalGuardingExample

Hazard ZoneHazard Zone

light curtain

ligh

t cur

tain

ligh

t cur

tain

include other body movements, which can affect the actual ap-proach 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 mo-tion to stop, or for the hazardous portion of the machine cycle to be completed. Note that different machine types have different stop-ping methods and mechanisms. Informative Annex D of ANSI B11.19-2003 contains excellent information on these consider-ations 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 dete-rioration. A stopping performance monitor will halt the machine when the stop time of the ma-chinery exceeds the set limit. This indicates that excessive brake wear has occurred.

What should you do if your machine does not have a stop-ping performance monitor? Add a percentage increase factor to the


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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 per-centage increase factor.

Dpf = The added distance, in inches, due to the depth penetra-tion factor from figure 4.3 or table 4.2. This is related to the mini-mum 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 resolu-tion, S, of the light curtain, Dpf is read directly from figure 4.3 or table 4.2.

This table assumes that Chan-nel 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 mount-ing schemes, refer to the example given later in this section. For safety light curtains with a mini-mum object sensitivity greater than 2.5 inches, please refer to Annex D of ANSI B11.19-2003.

Fig. 4.3 Depth Penetration Factor

Table 4.2 Omron STI Light Curtains Depth Penetration Factor

This material is reproduced with permission from American National Standard B11.1-1988 - Mechani-cal 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.

model Series S (mm) S (in.) Dpf (mm) Dpf (in.)

MC/MS 4700-12 12 0.47 17 0.7

MC/MS 4700-14 14 0.55 24 0.9

MC/MS 4700-20 20 0.8 44 1.75

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 46 1.8

1.0(25.4)

2.0(50.8)

3.0(76.2)

4.0(102)

5.0(127)

6.0(152)

7.0(178)

8.0(203)

0.0

(63.5)

Obje

ct S

ensi

tivity

(S)

Depth Penetration factor (Dpf)

2.5(mm)in

(50.8)2.0

(38.1)1.5

(25.4)1.0

(12.7)0.5

0.0in(mm)


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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 pen-etration 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 parenthe-

ses first:Ds = 63 in/sec. x (0.250 sec.) +

1.7 in.Multiply the result in parenthe-

ses 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 of-fered 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) + CWhere: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 detec-tion capability of the safety light

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 mmC = 850 mm where 40<d≤70 mm

The following identifies several factors which affect the calcula-tion of the safe distance formula:

First, the value of K, the oper-ator’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 calcu-lated 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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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) + CWhere:K =2000 mm/sec.t1 =0.100 sec.t2 =0.01 sec.C = 8(d-14); but C is never <0d = 20 mmS = 2000 mm/sec. (0.100 +

0.01 sec.) + 8(20-14)S = 2000 mm (0.11) + 48S = 268 mmRemember that for K=2000

mm/sec., S must be greater that 100 mm and less than 500 mm.

Horizontal Light Curtain Installations

Certain applications may use horizontal mounting of the light 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.

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

Figure 4.4

light curtain

intrusion angle of approach less than 30° to the sensing field.

intrusionApproach

<30°

Ds

h

floorfloor

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 sta-tion. 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 + 48Ds = 57.45 inches (1459 mm)

Table 4.6

Allowable Sensing field heights in inches (mm) ground level Devices that can Be reached Over (30 inches or less)Object mounting height Sensitivity minimum maximum< 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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Fig. 4.5 Reflective Surface Interference

Fig. 4.5a Example of correct mounting with proper alignment. The interrup-tion 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.

Fig. 4.5d Worst case alignment shows minimum distance from reflective surface, d, to one side of the beam center line.

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, mechani-cal guard or workpiece. Some examples of reflective surfaces may include shiny metal, glossy paint, foil, plastic or other similar material. A Test Procedure, such

as provided at the end of this sec-tion, must be used to test for this condition.

Calculations can provide the in-staller with a means of anticipat-ing 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

case condition where the trans-mitter 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.

transmitter receiver

reflective Surface

d

Perimeter of danger area

a

a

Operating range, r

Beam Angle, a


Approach direction

light beaminterrupted

a

d

reflective object


central beam

interruption

Sensing field

interruption

reflective Surface

receivertransmitter

Perimeter of Danger Area

reflection

a


Approach direction

light beaminterrupted

a

d

central beam

interruption

reflective Surface


Beam Angle, a

reflection


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When planning for or evaluat-ing an installation, consult the appropriate operating manual to determine the proper value for a.

Example — Reflective Surface Interference

For example, a MicroSafe MC4700 series is installed on an assembly machine. The distance between the receiver and trans-mitter is 6 ft. (1.8 m). What is the minimum distance a reflective object is permitted from the sens-ing field?

If you prefer, the calculations are:d = R/2 (tan 2a)R = 6 ft., a = 2.5°, thusd = 6/2 [tan 2 (2.5°)] = 3 tan 5° = 3 (0.0874) = 0.26 ft. or 3.1 in. (79 mm)

Thus, the center of the Micro-Safe beam line must be placed greater than 3.1 in. (79 mm) from a reflective surface.

■ Step 3. Physically Mounting the Light Curtain

Now that the minimum safe distance and reflective sur-face distance are known, the safety light curtain may now be mounted accordingly on the machine, stands or other mount-ing 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”

Fig. 4.9 Multiple Light Curtain Installation

Fig. 4.9b Preferred. The suggested orientation. The receivers are mounted back to back.

machine 1

machine 1

tran

smitt

er

rece

iver

tran

smitt

er

rece

iver

machine 2

machine 2

tran

smitt

er

rece

iver

rece

iver

tran

smitt

er

Fig. 4.9a not recommended. This arrangement may be subject to interference between the two light curtains.


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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 ConsiderationsThe 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 loca-tion include:

1. If the light curtain does not protect all access to the danger point, the unprotected access must be protected by other approved de-vices 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 perim-eter 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

! 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.

Figure 4.10a Correct

Figure 4.10b Incorrect

mirror


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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 hous-ings (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 mount-ed 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.

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 4. Preparation of the Light Curtain

Input power, output machine control, and, if used, remote func-tion control must be connected to the light curtain by means of cables protected by conduit.

It is recommended that a clear-ance 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).

■ Step 5. Configuring the Features of the Light Curtain

Some light curtains contain installation configuration op-tions which allow flexibility for your specific application needs. Examples of installation selec-tions include Operation Mode, Auxiliary Relay Selection, MPCE Monitoring, MTS, Exact Channel Select, Floating Blanking, Restart Interlock Mode and Range Selec-tion. See your installation manual or contact Omron STI for further information.


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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 pur-pose safety devices and are not designed for any specific type, model or brand of machine.

■ All safety-related machine con-trol 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 manufac-turer for advice and assistance on the connection of any safety device.

■ 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 ConnectionsLight 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 con-nected to a good electrical ground.

It is recommended that the light curtain be dedicated to its own source of input power where pos-sible. 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, depend-ing 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.

■ If a PLC (programmable logic controller) is used as the machine controller, consult the appropriate Omron STI light curtain manual for proper con-nection information.The installer must read and un-

derstand all instructions provided in the installation manual pro-vided 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 connect-ed or it will not provide maximum protection to the machine opera-tors and could result in serious injury. The machine control circuit wiring is the sole responsibility of the employer.


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PERIMETER GUARDING SPECIAL REQUIREMENTS

Perimeter guarding refers to in-stallations 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 horizontal mounting of the light curtain may prevent this.

For perimeter guarding instal-lation, the guarded machine or robot must be wired such that any detected interruption of the sens-ing 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 opera-tor. 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 intercon-nect a perimeter guard in certain installations where an external reset pushbutton or keyswitch is used. Always contact the machine manufacturer for advice and as-sistance on the connection of any safety device.

! 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 ModeRestart Interlock (Guard) Mode

allows the light curtain safety outputs to remain in a de-ener-gized state (latch condition) after an object detected by the light curtain is removed from the sens-ing field.

It may be desirable to employ Restart Interlock Mode when a light curtain is used in perimeter guarding installations.

Restart Interlock and Start In-terlock are two separate program-ming 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 In-terlock 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 instal-lation. 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 Stan-dards 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 electro-mechanical 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. Monitor-ing of the light curtain to machine control interface is necessary to detect a malfunction within the in-terface 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.


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A56

tB1

line / 24 VDc

neutral / 0 VDc

tB2

OSSD 1

OSSD 2

tB3

Auxiliary

tB7 1

2

1

2

mPce

StArt

PREFERRED CONNECTION DIAGRAM METHODCheck unit for proper voltage requirements before powering up unit.

lcm Series shown. consult product manual for complete details.

mPce 1

mPce 2

System control voltage

arc suppressor

arc suppressor

mPce 1 mPce 1

notes:

Arc or transient voltage suppression devicesshould only be installed across the coils of the machine control relays. never install arc or transient voltage suppressors across thecontacts of the safety light curtain. failure of the suppression in a short condition, acrossthe contacts, will result in an unsafe condition.

no external power is to be applied to theterminals of tB7.

the relay contacts of mPce1 and mPce2must be force-guided.

machine control contacts

mPce 1 mPce 2

1

2

3

1

1

2

23

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.

The method to arrest hazardous machine motion will vary de-pending on the type of machine. Control methodologies include hydraulic, pneumatic, clutch and mechanical braking systems. Thus, there are several varia-tions of MPCEs, including relays, contactors, solenoids and electro-mechanical valves.

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 re-quires 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 wir-ing diagram.

One NO open contact from each of two output relays are wired to two MPCE, as shown in fig. 4.11.

Figure 4.11


engineering guide

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tB1

line / 24 VDc

neutral / 0 VDc

tB2

OSSD 1

OSSD 2

tB3

Auxiliary

tB7 1

2

1

2

mPce

StArt

mPce 1

mPce 2

System control voltage

arc suppressor

arc suppressor

mPce 1 mPce 2

machine control contacts

mPce 1 mPce 2

1

1

2

2

3

NORMALLY OPEN, NORMALLY CLOSEDMACHINE CONTROL CIRCUIT CONNECTION

Check unit for proper voltage requirements before powering up unit.

lcm Series shown. consult product manual for complete details.

notes:

Arc or transient voltage suppression devicesshould only be installed across the coils of the machine control relays. never install arc or transient voltage suppressors across thecontacts of the safety light curtain. failure of the suppression in a short condition, acrossthe contacts, will result in an unsafe condition.

no external power is to be applied to theterminals of tB7.

the relay contacts of mPce1 and mPce2must be force-guided. to activate mPcemonitoring, Jumper 2 on the main controlboard needs to be installed in the on position.

1

2

3

NORMALLy OPEN, NORMALLy CLOSED MACHINE CONTROL CIRCUIT CONNECTION WITH RELAy OUTPUTS

Both safety output relays of the light curtain are used for this con-nection scheme. One NO signal is obtained by connecting to a safety

output relay. The NC contact is obtained from the second output relay. See figure 4.12.

This connection scheme re-quires a NC contact from one of the output relays.

The MPCE Monitoring con-nection as indicated on fig. 4.12 should also be installed. Note

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.

Using Arc Suppression Devices

Users should use arc suppres-sion devices, also called snubbers, across the coils of the machine control contactors when switch-ing 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.

! WARNING: Arc suppression and transient voltage suppression devices should only be installed

across the coils of the machine control relays. Never install these devices directly across the control output contacts of the light curtain. An arc or transient voltage suppres-sion device may fail with a short circuit and if installed across the contacts, will result in an unsafe condition.

Figure 4.12


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mPcemon.

Aux.Output

+24vdc

Shield

0vdc

OSSD 2

OSSD 1

Start

mPce2

mPce1

earthground

+24vdc 0vdc

0vdc

+24vdc

Shield

Start

mPce 1 mPce 2

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.

no external voltage is to be applied to terminalsmtS 1 or 2, mOn 1 or 2Damage to unit will occur.

nOte: mPce1, mPce2 are two user-supplied control relays with forced-guided contacts.

mPce1

machinecontrol

contacts

mPce2

gray

Brown

Drain

White

Blue

Braid

White

Brown

Shieldedcable mS4600 Xmtr

mS4600 rcVr

Power Supply

CONNECTING SOLID-STATE OUTPUTS TO AN STI RELAY MODULE

check unit for proper voltage requirementsbefore powering up unit

cOntrOlVOltAge

monitor

0vdc

OSSD 2

OSSD 1

42

41

32

31

24

23

14

13

rm-1

Shielded cable

Orange

Yellow

Pink

Shieldedcable

SUPreSSOr

SUPreSSOr

CONNECTING SOLID-STATE OUTPUTS TO AN STI RELAy MODULE

The following connection scheme shows an MS4600 light curtain with solid-state safety outputs interfacing with an RM-1 relay module. The concept is

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

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. Con-tact 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 con-tacts from MPCE1 and MPCE2 connected through the receiver's MPCE line to 0 VDC. If no exter-nal 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.

Figure 4.16


engineering guide

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A59

SUPreSSOr

mPcemon.

Aux.Output

+24vdc

Shield

0vdc

OSSD 2

OSSD 1

Start

mPce2

SUPreSSOr

mPce1

earthground +24vdc 0vdc

0vdc

+24vdc

Shield

Start

mPce 1 mPce 2

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.

no external voltage is to be applied to terminalsmtS 1 or 2, mOn 1 or 2Damage to unit will occur.

nOte: mPce1, mPce2 are two user-supplied control relays with forced-guided contacts.

mPce1

machine controlcontacts

mPce2

Shielded cable

gray

Brown

Drain

White

Blue

Pink

Drain

White

Brown

Shielded cablemS4600 Xmtr

mS4600 rcVr

Power Supply

Yellow

Orange

CONNECTING SOLID-STATE OUTPUTS TO TWO FORCE-GUIDED RELAYS

check unit for proper voltage requirementsbefore powering up unit

CONNECTING SOLID-STATE OUTPUTS TO TWO FORCE-GUIDED RELAyS

The following connection scheme shows a MS4600 light curtain with solid-state safety outputs directly driving two force-guided relays (MPCE). The

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 hazard-ous motion.

MPCE monitoring is performed on the final switching devices. It consists of a series set of NC con-tacts from MPCE1 and MPCE2

tied through the receiver's MPCE line to 0 VDC.

In some control systems, the PNP safety outputs can be directly interfaced into a safety PLC. Contact the machine manufacturer for the specifications on the PLC.

Figure 4.18


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StOP

Fig. 4.17 Using the Test Object

Use the test object to interrupt the sensing field along the center, bottom, sides and top of sensing field.

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 Moni-toring 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 proce-dures 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.

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.

Mirror Alignment HintsIf difficulty arises when using the

light curtain with Omron STI’s mir-rors, try using the following steps:

1. The mirrors must be parallel to the transmitter and receiver. If not, the beams will not be re-flected 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 machin-ery is disabled before working in a hazardous area!

■ Step 8. Checkout and Test Procedures

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.


Documents

Safety Light Curtains Light Curtain Installation Idownloads.deusm.com/designnews/1586-CTLRCwp060608x2.pdf · Note: Omron STI safety light curtains are available in two differ-ent