Tyco Electronics Galaxy SC Controller J85501F-1
Issue 13 February 2001 Glossary Appendix G - 5
paralleled in the plant, their output voltages are forced to be the same. In
a high voltage condition, it is important to discriminate between an
individual rectifier failure and a lightning-induced transient which
would affect all rectifiers in the plant. In the case of an individual failure,
the other working rectifiers in the plant should not be shutdown. When
the faulty rectifier(s) shut down, the plant voltage drops to normal, the
HV alarm retires.
The high voltage shutdown thresholds for float and boost mode should
typically be set 1.5 volts above the plant voltage set point for 48 volt
plants, and 0.75 volts above the plant voltage set point for 24 volt plants.
There is also a backup DIP switch high voltage shutdown that is used if
the basic controller fails.
In plants that have the RAISE VOLT feature of the Slope Thermal
Compensation enabled, special attention must be paid to the setting to
avoid nuisance alarms. STC increases the plant voltage at maximum 0.
1 volts for each cell in the battery string. The HFV setting should be
above the maximum the plant voltage will increase to. For example, in
a 48V plant with 24 cells the maximum change will be (0.1 x 24) = 2.4
volts. Adding 2.4 to the nominal plant voltage of 54.50 volts = 56.9 V.
The HFV level should be set above 56.9 volts and also above the HFV
level.
High Float
Voltage
The controller is equipped to detect a higher than normal voltage
condition on the plant bus. The source of the alarm is probably due to an
adjustment in the plant rather than due to a failure. This alarm permits
the high voltage shutdown level to be raised slightly, thus reducing the
number of nuisance shutdowns without decreasing plant reliability.
The high float voltage alarm (HFV) is considered a Power Minor alarm,
by default.
The high float voltage thresholds are typically set 1.0 volts above the
plant voltage set point for 48 volt plants, and 0.5 volts above the plant
voltage set point for 24 volt plants.
In plants that have the RAISE VOLT feature of the Slope Thermal
Compensation enabled, special attention must be paid to the setting to
avoid nuisance alarms. STC increases the plant voltage at maximum 0.
1 volts for each cell in the battery string. The HFV setting should be
above the maximum the plant voltage will increase to. For example, in
a 48V plant with 24 cells the maximum change will be (0.1 x 24) = 2.4
volts. Adding 2.4 to the nominal plant voltage of 54.50 volts = 56.9 V.
The HFV level should be set above 56.9 volts.
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