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Latching Alarms
Latching alarms describe the behavior of the software emulating a self latching relay. The coil is energized through
one of its own contacts, thereby holding itself energized. This type of relay requires an interruption in the latching
circuit for the relay to be de-energized. This is the function of the alarm reset button.
This feature is implemented in software for alarms warn and alarms programmed with the latching
option. Once an alarm has occurred, the associated LED and relay(s) will be held in their alarm
state even though the original alarm conditions have returned to normal. The LED and relay(s) will
not be returned to normal until the alarm condition has subsided and the alarm reset button has
been pressed.
Energized Relays (Fail Safe)
Normally, an alarm relay will remain de-energized until an alarm occurs, at which time the coil is
energized. This describes a non-failsafe relay. When an alarm relay is programmed to be failsafe,
its coil remains energized in normal, no alarm condition, and de-energizes during an alarm. This
permits the relay contacts to be used to detect power failures as well as their assigned function.
Safety Suggestion! It is a safe practice to make all optional remote relays programmed as fault
relays, failsafe, so that power failures may be sensed. A separate power source is required for the
alarm devices, e.g. horns & lights, if used to detect power failures.
The common fault relay is energized (failsafe) and cannot be programmed otherwise
The warn and alarm relays by factory default are set for de-energized operation but can be programmed otherwise.
Note: Any relay, programmed as energized (fail safe), will have contact operation reversed to the terminal
strip labeling. All labeled normally open (NO) contacts will operate as normally closed (NC) and all labeled
(NC) contacts will operate as (NO).
Common Alarm Relays
There are four SPDT common alarm relays located on the CPU/power supply board.
Fault Relay
Activated when any channel fault is detected.
Warn Relay
Typically activated when any channel low alarm set point is exceeded. This relay can be
programmed to activate off any one channel or group of channels for either warn and/or
alarm level.
Alarm Relay Typically activated when any channel high alarm set point is exceeded. This can be
programmed to activate off any one channel or group of channels for either warn and/or
alarm level.
Horn Relay
This relay can be programmed to activate off any one channel or group of channels for either
warn and/or alarm level.
Summary of Contents for QuadScan II 7400
Page 10: ...5 of 116 Quick Start Programming Menu Tree...
Page 20: ...15 of 116 Figure 5 Mounting Dimensions of Model 7400...
Page 24: ...19 of 116 Figure 9 Battery Backup P N 096 0719 Outline Interconnection Wiring...
Page 60: ...55 of 116 Figure 13 Interconnect Wiring Between 7400 Remote Relay Assembly...