Dimensions Unlimited
5
Technical Description
3.1 Standby Power System:
A Standby Power System is a DC to AC power inverter with a battery charger “B3” and
an automatic fast transfer switch “T”.
Note:
In this manual, we will use the acronym SPS when referring to a Standby Power
System.
A remote LCD control/status panel controls the SPS and provides system status by
displaying user-friendly screen messages.
The system has two operational modes: Inverter power mode and external power mode.
3.1.1 Inverter Power Mode:
The SPS converts DC power from batteries to usable
120 VAC, 60 Hz power. The direct current (DC) that enters the SPS is filtered by a large
input capacitor and switched “On” and “Off” by the Metal Oxide Silicon Field Effect
Transistors (MOSFET) at a rate of 60 cycles per second, and directed into the
transformer which steps the voltage up to 120 volts. The unit has a Digital System
Processor (DSP) to control the output voltage and frequency as the DC input voltage
and/or output load varies. The signal output waveform shape is not sinusoidal; it has a
total harmonic distortion of 31% and a maximum single harmonic distortion of 25%.
3.1.2 External Power Mode:
120 VAC, 60 Hz external power can be applied
directly to the SPS by hardwire connections to the AC input wire leads provided in the
field-wiring compartment. When external power is present, the internal transfer switch
cannot be defeated; it automatically turns the DC to AC inverter OFF and activates the
three-step battery charger. At this time the loads attached to the SPS output will
operate directly from the external power line even if the SPS was turned OFF manually.
The internal transfer relay automatically switches the SPS back to “inverter power” mode
in the absence of external power whenever the SPS was previously set to ON.
