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5C3B9@D9?> - Supervision of power to 4-wire detectors is necessary to ensure their operation. Supervision is accomplished by
installing a Power Supervisory Relay (PSR), Model PSR-2040 or its equivalent after the last detector. The relay contacts are nor-
mally closed when power is present at the last detector. These contacts are wired in series with the supervised detection circuit. A
loss of power due to a break (open) in the 4-wire detector power wiring will allow the Power Supervisory Relay to de-energize
opening the closed contact and causing a trouble in the detection circuit.
Notes:
1. PSR-2040 Power Supervisory Relay shown with relay in the normally energized supervisory state (closed).
2. Install Power Supervisory Relay in the last detector back box.
3. ELR-4.7K - End-of-line device supplied with the control panel.
4. Some 4-wire detection devices provide their own power supervision. For these types of devices, a power supervisory
relay may
not be required.
~ 23 ~
#19>?1B4K#
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