GE Industrial Solutions CPS2400U - Manual (Page 45)

CPS2400U Upstream System – 19” Product Manual CPS2400U
850028186 r04 December 2013 45
Alarm Card Logical Operation of LEDs and Alarm Relays
The Alarm Card contains a pair of form C relays to provide shelf PMN and PMJ isolated closures.
Both PMN and PMJ relays will signal alarm if both A and B input fail.
Relays coils are energized to signal normal (no-alarm) and are redundantly powered by both the A & B input buses.
The relay circuit interfaces to a pair of parallel buses connected to each of the 16 Converter/Limiter Cards. Each
Converter has an open collector output on the bus, and pulls the bus low to chassis ground when it is asserting an
alarm. The PMN/PMJ circuit on the Alarm card recognizes the bus state change and denergizes the associated alarm
relay, signaling alarm. The alarm card separately monitors both the PNM and PMJ bus. When the PMN bus is active
(pulled low), the Alarm card asserts a PMN relay and lights the ALM LED Yellow. When the PMJ bus is active (pulled low),
the Alarm card asserts a PMJ relay and lights the ALM LED Red.
The Alarm Card ignores the state of the PMN bus (and does not assert a PNM relay/LED action) while an active PMJ is
present. This is necessary since a single LED is used for both Minor (Yellow) and Major (Red) visual indication.
The Alarm Card also monitors the -48V dc inputs and asserts PNM/PMJ for conditions as described in the earlier section
dealing with input voltage monitoring.
The Alarm Card also monitors the two fan tray alarms. When either of the two fan tray alarms is active, the Alarm Card
asserts a PMN relay and Yellow ALM LED. When both of the fan tray alarms are active, the Alarm Card shall assert a PMJ
relay and Red ALM LED.
The Alarm Card shall also monitor its internal I
2 C to RS-485 conversion processor. A failure of this processor shall
constitute a PMN condition.