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m908 User Manual, Rev. G
horizontal to 30º.
3.9 PSU Description
The m908 monitor controller is powered by the A140 Dual Redundant Power
Supply Unit. The A140 features Universal AC Input for operation from 100-
240VAC. This new generation external power supply contains two complete power
supply modules which operate in parallel. Should one power supply module fail
the other module will continue to power your system with no interruption. The A140 contains an
intelligent microprocessor that monitors all of the DC rail voltages and reports fault conditions by
flashing front panel LEDs. In the unlikely event that a power supply module fails the A140 front
panel LEDs with flash to indicate which power supply module is at fault. The power supply
modules are easily replaced in the field which minimizes any possible system down time.
A low speed serial communication link allows the power supply unit to communicate voltage
rail status to the main ACU processor.
Under normal operating conditions the four front panel Status LEDs will be solid green.
If a DC output of power supply module #1 becomes too low or too high the corresponding LED
will flash once repeatedly. If a DC output of power supply module #2 becomes too low or too
high then the corresponding LED will flash twice repeatedly. If this happens contact Grace
Design Technical Support at 303-823-8100 x105 or [email protected]
3.10 PSU Front Panel Controls and Indicators
1. Voltage rail monitor LED x 4: These LEDs will illuminate steady green under normal operation.
2. Mains power switch: This is the AC Mains disconnect device. It must remain accessible.
3.11 PSU Rear Panel Connections
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A140 REDUNDANT DC P OWER SUP PLY UINT
OK
P S #1 FAULT
PS #2 FAULT
CAUTION: CONNECT DC P OWER CORD BEFORE TURNING ON P OWER
+18 V
+6.5V +50V
-18 V
1
2
Illustration 7: PSU Front Panel