52 Keysight PXIe Chassis Family User Guide
Power Supply Operation Power Supply Capacity
Over Temperature Protection
The chassis is rated to perform from 0 to 55 °C. As long as the power limits are
adhered to, an over temperature condition is unlikely to occur. The Primary
Power Module (PPM) shuts down if its internal temperature exceeds 110 °C.
To recover from a suspected over temperature shutdown, the PPM internal
temperature must be below 110 °C and the chassis must be power cycled. Power
cycling of the chassis should be performed by detaching and re-attaching the
power cord. Neither the front panel ON/OFF push button nor the Inhibit signal on
the rear panel DB-9 connector will function if the PPM is shut down.
If the chassis is power cycled but does not resume operation, either the PPM was
not at fault or the PPM internal temperature is still above 110 °C. Additional
cooling time should be allowed followed by another power cycle to see if that
resolves the problem.
Over-current Protection
The Primary Power Module (PPM) has over-current protection on its 5V
aux
, 12V,
-12V, and 3.3V outputs.
An over-current condition results in the PPM outputs (5V
aux
, +12V, -12V, and
3.3V) unable to sustain the output voltage within the specified range. When the
output voltage drops below approximately 20% from nominal, the chassis PPM
shuts down in order to protect the power supplies from damage. The over current
protection on the +5 V DC-to-DC converter output is specified typically at 135%
or greater and also results in the PPM shutting down.
The M9010A has a protective algorithm to monitor the AC input current and
automatically power-off if the AC input current goes above 8.5A. When
automatically powered-off, the chassis will continually blink the power LED 3
times.
If the chassis is operating within its normal ambient temperature
range of 0-55° C and is operating within the power limits
described previously, an over temperature condition is unlikely to
occur. Therefore, if the chassis appears to be powered down (for
example, based on the front panel LEDs being off), you should
consider other possible causes prior to considering an over
temperature condition. See the Keysight PXIe Chassis Service
Guide for further information.
Note that it is not possible to determine the temperature of the
PPM based on the temperatures reported by the air flow exit
temperature sensors. The PPM and the air flow exit temperature
sensors have different ventilation air flows.
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