ABB GPS4827, User Manual

Page: 76 / 96

Page 76
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1. The plant voltage must be above the level set for the High Voltage alarm at the VOLTAGE ALARMS
menu screen: MENU
→
CONFIGURE
→
FLOAT SETTINGS
→
VOLTAGE ALARMS
2. The rectifier must be delivering a current of at least 10% of its capacity.
3. The rectifier ’ s current output must be unbalanced by more than 10% from the average output
currents of the other rectifiers.
Because item 3 is difficult to achieve in a simulation test of properly functioning serial rectifiers, (even
with load share disabled), rectifiers are tested one at a time, rather than as a group. Slightly different
test procedures are used for special applications in batteryless plants. Serial rectifiers have their own
internal restart circuits which will function 3 times before the rectifier locks itself out and initiates a High
Output Rectifier Fail Alarm to the controller. If there is a sufficient interval between restart and a
subsequent shutdown the rectifier resets its restart counter. The controller initiates a restart signal a
few seconds after the first RFA (HO) alarm is received. After the second RFA (HO) is received, the
controller waits 5 minutes before sending one additional restart signal.
1.
Verify the Auto Restart is enabled from the front panel menus:
2. Turn off all rectifiers except the rectifier under test by operating their
power switches to STBY.
3.
Adjust the dummy load to provide 10 to 30% of the rectifier ’ s output capacity.
4.
Using the Voltage Alarms Menu Screens, note High Voltage Alarm
threshold value.
5.
Using the Float Settings Menu Screens, select Set Point and note the
value.
NOTE:
The next step WILL RAISE the system voltage.
6.
Use the Arrows, and UP/DOWN keys to change the system float voltage setpoint to 0.1V above the High
Voltage Alarm Threshold.. Press ENTER
to save.
7.
Controller Observations:
•
The plant voltage increases
•
Power Major alarm (PMJ) is generated