8�4 Synchronizing The Maintenance Bypass - Alpha Technologies AMPS HP2 Power System Installation & Operation Manual

8.4 Synchronizing the Maintenance Bypass
For system configurations that use a generator for the AC input, the safest way to initiate a maintenance bypass is
to follow the instructions in the Initiate Zero Phase Shift wizard.
This wizard should be used whenever the inverter system has to be put into or taken out of bypass. This prevents
the inverters from turning off when the bypass switch briefly short-circuits the AC input and output.
8.4.1 Implement the following sequence before switching the unit from
Inverter mode to Bypass mode.
NOTE:
IMPORTANT: Make sure that the Internal MBS is in Inverter mode.
1. The inverter input breaker should be on. The inverters should be synchronized to the line, and for all status
LEDs to turn green.
2. The inverter output breaker should be ON.
3. Go to, Power System > Inverter System > System Functions > Zero Phase Shift.
4. Initiate Zero Phase Shift wizard.
5. The wizard shifts the phase and voltage of the AC output to match the input.
6. Switch the internal bypass switch to Bypass (within the time limit specified in the Zero Phase Shift wizard). If
present, switch the external bypass switch to Line.
8.4.2 Implement the following steps before switching the unit from
Bypass mode to Inverter mode:
NOTE:
IMPORTANT: Make sure that the Internal MBS is in Bypass mode.
1. Switch external bypass to UPS.
2. Switch on the inverter input breaker. Wait for the inverters to synchronize to the line, and for all status LEDs to
turn green.
3. Switch on the inverter output breaker.
4. Go to, Power System > Inverter System > System Functions > Zero Phase Shift.
5. Initiate Zero Phase Shift wizard.
6. The wizard shifts the phase and voltage of the AC output to match the input.
7. Finally, switch the Internal MBS from Bypass to Inverter (within the time limit specified in the Zero Phase
Shift wizard).
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