March 2021 Page 75 of 143 59812-K007 Rev 17
Whilst any Detectors are in a Backup Alarm condition the Accept key is inoperative until the oil
mist level drops below 3.0mg/l.
It is possible for a healthy Detector to produce a Backup alarm if the level of oil rises very rapidly.
NOTE - The Backup Alarm will not operate the Slowdown/Shutdown Relay
3.17 RELAY OPERATION
Communication of alarm and fault conditions
Management System (AMS) is via a series of volt free contact relays. Individual relays are provided for
Pre-Alarm, Slowdown/Shutdown Alarm, Backup Alarm and Fault. For each output connections are
provided to the relay common, normally open and normally closed contacts providing the flexibility to
meet the interface requirements of the AMS.
The actions of the relays are detailed below:
Activated when the oil mist level of a detector
rises above the configured pre-alarm level.
Slowdown/Shutdown Alarm Relay
Activated when the oil mist level of a detector
rises above the configured slowdown/shutdown
alarm level.
Activated when oil mist level of a detector rises
above 3mg/l for a period of 5sec or more.
Operation of the Backup Alarm Relay is software
independent and cannot be reset until the oil mist
level falls below 3mg/l.
The Fault Relay is normally activated and de-
activated when a fault occurs on the Control Unit
or Detectors.
In the event power is lost to the Control Unit the
relay is de-activated ensuring a fault is indicated
to the AMS.
A graphical representation of the relay operation is shown below:
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