Alpha Technologies VMX Series - Manual (Page 12)

12 017-940-B0-001, Rev. A
1.0 Introduction to the VMX Power Supply
The Alpha family of VMX Uninterruptible Power Supplies is designed for powering signal processing
equipment in cable television and broadband LAN distribution systems. The VMX provides a critical
load with current-limited, regulated, AC power that is free of spikes, surges, sags and noise.
During AC line operation, AC power entering the power supply is converted into a quasi square wave
and is regulated by a ferroresonant transformer at the required output voltage. The regulated voltage
is connected to the load via the O
UTPUT
1-4 ± terminal block connections, and some power is directed
to the battery charger to maintain a fl oat charge on the batteries.
When the incoming AC line voltage signifi cantly deviates from normal, the VMX Power Supply
automatically switches from the AC line to Standby mode, maintaining power to the load. During the
switch to standby operation, energy in the module’s ferroresonant transformer continues to supply
power to the load. While in Standby mode, the VMX powers the load until the battery voltage reaches
a low-battery cutoff point.
When utility power returns, the VMX Power Supply waits a short time (approximately 10 to 20
seconds) for the utility voltage and frequency to stabilize, and then initiates a smooth, in-phase
transfer back to AC line power. Once the transfer is complete, the battery charger recharges the
batteries in preparation for the next event.
Key components of the VMX Power Supply include a line-conditioning ferroresonant transformer,
resonant capacitor, transfer isolation relay, and inverter. The inverter contains circuitry for the three-
stage temperature-compensated battery charger, DC to AC converter (inverter), AC line detector, and
Smart Display. An optional communciation module provides remote status monitoring.
The VMX Power Supply features:
• Line Interactive Ferro Technology (LIFT)
• Smart Display
• Built-in programmable battery self-test
• 3-stage temperature compensated battery charger
• Automatic battery detection
• Field programmable fl ash memory
• Four-Output Protection Interface Module
• Digital status monitoring (optional)
Fig. 1-1, VMX Power Supply