Specifications

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Publication S117-CA001A-EN-P
Presence Sensing Safety Devices
Safety Light Curtains
2-10
Overview
General Principles
2-Opto-electronics
Safety Switches Operator
Interface
Logic Power
R
Typical System Configurations
1. Optic heads (operate on 24V DC)—ordered as a pair
(transmitter/receiver)
2. Cables—two required per pair—specify length
Optional components (customer or Allen-Bradley Guardmaster
supplied):
3. Safety Relays
2
1
3
Muting
PAC safety light curtains are also used in conveyorized processes
and very often are used in conjunction with a muting module.
Muting is the temporary automatic suspension of the protective
function of the safety light curtain.
Muting modules can be integrated into the light curtain's receiver or
external to the light curtains. Rockwell currently offers external
muting modules.
This muting function allows material to move through the safety light
curtain’s sensing field without stopping the machine, however, if a
person attempts to pass through the safety light curtain, they will be
detected and the machine will stop. The differentiation between
material and personnel is determined by the use of muting sensors.
These muting sensors create a particular switching sequence
together with the safety light curtain as the material passes through
the process.
GuardShield GuardShield
PAC
Transmitter
PAC
Receiver
Corner Mirror
The Allen-Bradley Guardmaster GuardShield and GuardShield Safe
4 safety light curtains are two-box designs. This means the safety
light curtain does not need a separate controller to operate.
Therefore, the safety outputs of the light curtain (OSSDs) can be
connected directly to any safety relay that will accept two PNP
inputs.
The following are some common configurations of light curtain
systems. The numbers on the drawing indicate the ordering steps to
follow to ensure that a complete system is specified.
Components required for a “Guard only” system:
PAC safety light curtains are generally of resolutions that provide
detection of limbs and bodies of personnel, i.e., 50 mm, 70 mm,
90 mm and up. It is also common for PAC safety light curtains to be
offered with a limited number of infrared beams spaced at
consistent distances from one another, such as 3 beams with
400 mm spacing between beams, or 2 beams with 500 mm beam
spacing.
Allen-Bradley Guardmaster PAC safety light curtains consist of two
families, the GuardShield PAC family and the Safe 4 PAC family. The
GuardShield PAC family is offered with multiple beams with various
beam spacings for short range applications (16 meters or less). The
Safe 4 PAC family is offered with multiple beams (2 or 3) with
various beam spacings for long range (5…30 meters).
PAC safety light curtains are opto-electronic through-beam devices
typically used to detect personnel around hazardous equipment or
machinery. PAC safety light curtains are usually used as an opto-
electronic fence and when used with corner mirrors, can provide
two- or three-sided detection around the perimeter of hazardous
machinery.
Perimeter Access Control (PAC)