Alpha Technologies GMX-915 - Manual (Page 13)

13 017-932-B0-002, Rev. B
1.0 Introduction to the GMX Power Supply
The Alpha family of GMX Uninterruptible Power Supplies is designed for powering signal processing
equipment in cable television and broadband LAN distribution systems. The GMX 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 V
out
± terminal block connections, and some power is directed to the
battery charger to maintain a float charge on the batteries.
When the incoming AC line voltage significantly deviates from normal, the GMX 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 GMX powers the load until the battery voltage reaches
a low-battery cutoff point.
When utility power returns, the GMX 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 GMX 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 GMX Power Supply features:
• Line Interactive Ferro Technology (LIFT)
• Smart Display
• Built-in programmable battery self-test
• 3-stage temperature compensated 10A battery charger
• 150W auxiliary UPS output
• Automatic battery detection
• Field programmable flash memory
• Optional embedded DOCSIS or ethernet status monitoring cards
Fig. 1-1, GMX Power Supply