Theory of operation
Power Supply m
odules
The two Power Supply modules and the Combiner board are the main components
of the redundant power subsystem. Operation with one supply module is also
supported, b
ut there is no redundancy.
The Power Supply modules contain the 100-240 VAC to 12 V supply, a fan, and
the Power Mo
dule board, which adapts the cables to a board-to-board header. The
Power Module board contains a temperature sensor to measure the power supply
exit airflow, and an EEPROM to log hours of operation. Since the Power Module
board tracks the use time on the other supply components, replacing components
within the supply module is not allowed. The connector from the Power Module
board to the Combiner board has the 12 V DC output, and the 100-240 VAC input,
as well a
s I2C communication and fan drive signals.
The Power Module board passes the AC voltage going into the power supply, and
the DC vo
ltage from the supply to the instrument. The AC is carried on large pins
with bigger spacing gaps in the board to board connector J1 as needed for safety
on the line voltage. The AC pins are shorter on one side of the connector so that
the GND connects first and disconnects last. The DC returning from the supply
also uses large pins on J1, but that is to handle the current.
The Power Module board has an I2C bus for the memory and temperature sensor.
The I2C pins in the connector are shorter so that ground and power are applied
first when the module is installed.
2–8 ECO8000 Series Service Manual
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