NSM-3E Signal Monitor Unit
Operations Manual
Eberle Design Inc.
Page 2
input. When voltages on all inputs to a channel are sensed as inactive for less than 700
msec, the unit will not transfer the Output relay contacts to the Fault position.
Red Failure Monitoring is disabled when the Red Enable input is not active.
1.3.1 WALK DISABLE (RED MONITORING)
This option will modify the operation of Red Monitoring on the NSM-3E Signal Monitor.
When enabled, the Red Monitoring function will not monitor the Walk field outputs. Absence
of signals on the Green, Yellow, and Red field outputs of a channel will place the NSM-3E
Signal Monitor into the fault mode causing the Output relay contacts to transfer. This
function is enabled by the front panel option switch labeled "WALK DISABLE". See also
section 2.2.2.
1.4 VOLTAGE MONITORING
Inputs are provided for monitoring two +24VDC supplies and the Controller Voltage Monitor
(CVM) output from the controller. Should loss of proper signal occur at any of these inputs,
the NSM-3E Signal Monitor will de-energize the Output Relay causing the two sets of
contacts to transfer and will illuminate the appropriate front panel indicator(s). The Monitor
will automatically reset when the correct input signals are restored to these inputs if the unit
had not already been triggered by a previous fault condition. A 24V Monitor Inhibit input is
provided to facilitate the use of these monitors with pre-timed mechanical controller
installations.
1.4.1 VOLTAGE MONITOR FAULT LATCH
When the 24V Latch option is enabled by the front panel switch labeled "24V LATCH", the
absence of the proper voltage level at either of the two 24VDC inputs (24V-I & 24V-II) will
place the NSM-3ESignal Monitor into the fault mode causing the Output relay contacts to
transfer. The 24V-2 and / or the 24V-1 indicator(s) will be displayed on the Fault Status
Display along with the field output signals active at the time of the voltage fault. Restoration
of the voltage levels will not reset the fault state of the Monitor. Only a Manual Reset or
External Test Reset command will reset the Monitor.
1.4.2 CVM FAULT LATCH
When the CVM Latch option is enabled by the front panel switch labeled "CVM LATCH",
the absence of the True state at the CVM Input will place the NSM-3E Signal Monitor into
the fault mode causing the Output relay contacts to transfer. The CVM indicator will be
displayed on the Fault Status Display along with the field output signals active at the time of
the voltage fault. Restoration of the True state will not reset the fault state of the Monitor.
Only a Manual Reset or External Test Reset command will reset the Monitor.
1.5 AC+ BROWN-OUT / INTERRUPTION DETECTION
When the AC+ line voltage is below the drop-out level for 475 msec (+_25 msec) the NSM-
3E Signal Monitor will suspend all fault monitoring functions, de-energize the Output relay,
and de-energize the Start relay. The POWER indicator on the front panel will flash at a rate
of 2Hz to indicate the brown-out status.
When the AC+ line voltage returns above the restore level for 100 msec (+_16 msec) the
monitor will resume normal operation and the POWER indicator on the front panel will
remain illuminated. After a 2.5 second (+_1 second) delay the Start relay will be energized.
After a programmable delay determined by the minimum flash function switches on the
front panel the Output relay will be energized.