ABB GPS4827, User Manual

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Page 67
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4.
ALARM THRESHOLDS
High Voltage
When the plant voltage exceeds this threshold, the plant High
Voltage Alarm (HVA) is turned ON, and the controller will send a
signal to the rectifiers to shut down in an orderly and timely
fashion. This will also light the Major (MJ) LED, and activate the
PMJ relay (assuming there is no alarm with CRITICAL severity
level active). Move the cursor to the fields and use the <+> or
< - > key to adjust the High Voltage shut down alarm for FLOAT
mode to the desired level. Press <ENTER> to save the change.
High Voltage Float
When the plant voltage exceeds this threshold, the plant High
Float Voltage Alarm (HFV) is turned ON, and this will also light
the Minor LED, activate the PMN contact closure (assuming
there is no alarm with CRITICAL or MAJOR severity level active).
The purpose of this alarm is to indicate that the plant voltage is
high probably due to an adjustment in the plant rather than due
to a failure. This alarm allows the High Voltage (HV) shutdown
threshold to be raised slightly, thus reducing the number of
nuisance shutdowns without decreasing the plant reliability.
Move the cursor to the fields and use the <+> or <
- > key to
adjust the High Voltage shut down alarm for FLOAT mode to the
desired level (normally less than the HV threshold). Press
<ENTER> to save the change.
Battery on
Discharge
If the plant voltage is less than the threshold value, the Battery
Discharge alarm is turned ON, this in turn activates the PMJ and
BD relay, light the MAJ and BD LEDs. Move the cursor to the
fields, and use the <+> or <
- > key to adjust the threshold to the
desired level. Press <ENTER> to save the change.
Very Low Voltage
This alarm threshold is used to indicate that the system voltage
is very low, and that the batteries have discharged to a
dangerously low depth. When the plant voltage falls below this
level, the Very Low Voltage (VLV) and Power Critical alarm will be
generated. Move the cursor to the field and use the <+> or
< - > key to adjust the threshold value. Press
<ENTER> to save the change.