R
GuardShield™ Safe 2 Safety Light Curtain User Manual
6
Original instructions
Safety Functions
All GuardShield Safe 2 safety light curtains operated as on/off devices,
meaning the OSSD outputs switch off/on according to an obstruction or
clearing of the detection field.
System Testing
The GuardShield Safe 2 performs a complete system self-test at power up
and switches to the ON state if the system is properly aligned and the
protective field is unobstructed.
External Test (Machine Test Signal)
Normally the test input at the transmitter is installed with a short-circuit
jumper to activate the transmitter. A test cycle of the system can be
triggered by an external test signal to the GuardShield Safe 2 transmitter.
Supplying or removing a signal (+24V DC) via a N.C. or N.O. switch at
the test input deactivates the transmitter for the duration of the test
signal, simulating an interruption of the protective sensing field (see also
page 11).
Response Time
The response time of the GuardShield Safe 2 safety light curtain depends
on the height of the protective field, the resolution, and the number of
light beams (see table on page 20).
Determining the Safety Distance
The light curtain must be mounted with proper safety distance
• From the point of danger
• From reflecting surfaces
US Safety Distance Formula
This distance, referred to as the safety distance, must be properly
calculated prior to determining the safety light curtain protective height
and mounting the light curtains on the machine. Failure to properly
calculate this safety distance may result in operator injury.
In the United States there are two formulas that are used to properly
calculate the safety distance. The first, the OSHA formula, is the
minimum requirement for the calculation of the safety distance. The
second formula, the one recommended by Rockwell Automation, is the
ANSI formula, which incorporates additional factors to be considered
when calculating the safety distance.
OSHA Safety Distance Calculation Formula
The OSHA safety distance formula as specified in CFR Subpart O
1910.217 is as follows:
Ds = 63 X T
S
Ds
Safety Distance in inches
63
Is the OSHA recommended hand speed constant in inches per
second
Ts
Is the total stop time of all devices in the safety circuit, measured in
seconds. This value must include all components involved in
stopping the hazardous motion of the machinery. For a
mechanical power press it is the stopping time measured at
approximately the 90º position of the crankshaft rotation.
The T
S
number must include the response times of all devices, including
the response time of the safety light curtain, the safety light curtain
controller (if used), the machine’s control circuit and any other devices
that react to stop the hazardous motion of the machinery. Not including
the response time of a device or devices in the stop time calculation will
result in insufficient safety distance for the application. This may result
in operator injury.
The ANSI Safety Distance Formula
The ANSI safety distance formula, which is the Rockwell Automation
recommended formula, is as follows:
D
S
= K x (T
S
+ T
C
+ T
r
+ T
bm
) + D
pf
Ds
Minimum safety distance between the safe guarding device and
the nearest point of operation hazard, in inches.
K
Hand speed constant in inches per second. The ANSI standard
value is 63 inches per second when the operator begins reaching
toward the point of operation hazard from rest. NOTE: ANSI
B11.19 1990 E4.2.3.3.5 states “The value of the hand speed
constant, K, has been determined by various studies and although
these studies indicate speeds of 63 inches/second to over 100
inches/second, they are not conclusive determinations. The
employer should consider all factors, including the physical ability
of the operator, when determining the value of K to be used.”
Class 2 Laser
To prevent exposure to laser radiation, do
not expose your eyes to the laser. Turn ILAS
off if not in use.
IMPORTANT
The protective system must be tested for
proper operation after each and every
change to the configuration.
IMPORTANT
Determining Stop Time: The measurement of
stopping time (Ts) must include the stopping
times of all devices in the stop circuit. Not
including all device and control system
elements when calculating Ts will result in an
inaccurate safety distance calculation.
ATTENTION
The GuardShield Safe 2 safety light curtains
must be mounted at a sufficient distance
from the pinch point or point of operation
hazard to help ensure that the machine stops
before a person’s finger, hand, arm(s), or body
reaches the hazard.
IMPORTANT
Regardless of the calculated safety distance,
GuardShield Safe 2 safety light curtains
should never be mounted closer than six
inches from the point of operation or pinch
point hazard.
