Model SS
Solid State Safety Light Curtain
Product Overview
The Ultimate in Safety - Quality -
Value
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The
Model SS is an infrared safety light curtain
that is designed to the IEC 61496 standard.
When properly installed, it protects the
machine operator by passing an invisible
infrared light beam across an area to be
guarded and examining whether or not the light
beam(s) are blocked. If the light beam(s) are
blocked, monitored solid state outputs will
open, issuing a “STOP” command to the machines
normally closed (N.C.) “STOP” circuit. The
System is composed of a transmitting unit
(EMITTER), and a receiving unit (RECEIVER). The
entire system is control reliable Category 4
(per IEC 61496). A single fault anywhere within
the Model SS will not prevent at least one of
the solid state outputs from opening up,
(allowing a “STOP” command) when either a beam
is broken or an internal fault
occurs.
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Theory of
operation.
The Model SS protects an area by projecting a
curtain of infrared light. The infrared emitters and receivers
face each other across the field to be protected. Each
emitter/receiver pair is spaced along the length of the pylons
at regular intervals from .5", up to 8" depending on the
application. The smaller spacing are for finger guarding, the
larger spacing are for body protection. The emitter/receiver
pairs are scanned sequentially (one at a time) by a very short
pulse of infrared light starting from bottom (cable end), and
working up to the top, until every beam pair has been scanned.
Two 16 bit computers in the emitter pylon and two 16 bit
computers in the receiver pylon control the operation, as well
as cross check each pylon.
The
System.
The Model SS employs infrared
technology in a small sealed NEMA 4 aluminum housing with an
infrared passing (daylight filtering) acrylic lens. This system
provides harmless invisible protection and an unobstructed view
of the guarded area. There are two parts to the Model SS: An
Emitter pylon and a Receiver pylon. The Emitter pylon has no
outputs, but does contain a digital CAN data network to allow
it to be linked to the Receiver pylon (although not required
for operation). The Receiver pylon contains the digital CAN
data network and two monitored solid state 24vdc outputs. Both
pylons are synchronized to each other either via the CAN data
network or electronically.
System Safety.
The Model SS incorporates
redundant, and diverse technology that provides a backup for
every system that could cause an unsafe
condition.
External Device
Monitoring (EDM).
A method in which the Model SS Category 4
safety light curtain logic monitors the state of various
external control devices. The control devices are external and
not part of the Model SS light curtain pylons. A lockout or
stop signal will result if an unsafe state is detected in an
external device. The External Device Monitoring (EDM) is an
optional function of the Model SS safety light curtain for
monitoring the status of external devices such as gate and door
switches, safety switches or the main control element of the
drive (MPCE). Solid state outputs are turned on separately to
be checked and assure neither output has been shorted, before
fully turning on.
Design
Criteria.
Designed to meet IEC 61496-1
& 2, UL 1998, UL subject 491, OSHA, ANSI, CSA, ANSI-RIA
R15.06-1999
Microprocessor redundancy for
both Emitter and Receiver pylons
Redundant, monitored, 24vdc solid
state outputs (PNP)
Watchdogs on CPU’s and outputs
prevent unintentional output during
lockups.
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