Alpha Technologies VMX Series - Manual (Page 30)

30 017-940-B0-001, Rev. A
5.0 Operation, continued
5.1 Start-up and Test, continued
Standby Operation
1. Perform the following procedure after successful completion of a self-test with the VMX
Power Supply operating normally in AC line mode: Momentarily fail the AC utility input
power by switching the AC circuit breaker (service disconnect) to OFF.
2. The VMX Power Supply should start operating in the inverter mode. Use the Smart
Display or a true RMS voltmeter to verify output at the OUTPUT 1-4 ± terminals. Output
voltages should appear within ±5% of 87Vac (for 90V units), 63Vac (for 60V units), or
48Vac (for 48V units) at nominal line input voltage.
3. Return the VMX Power Supply to AC Line mode by switching the AC (service disconnect)
circuit breaker to ON. The transfer back to utility power may take 10 to 20 seconds. This
delay allows the utility voltage and frequency to stabilize before the module’s phase-lock
circuitry is activated. The module then synchronizes the inverter’s waveform to the utility’s
before initiating a smooth, in-phase transfer back to utility power. Once the transfer is
complete, the smart display will report: OPER MODE = LINE.
4. The VMX Power Supply is now fully operational.
SETTING LOW (-5%) HIGH (+5%)
87Vac 82.65Vac 91.35Vac
63Vac 59.85Vac 66.15Vac
48Vac 45.60Vac 50.40Vac