Incoming AC power shall be converted to a regulated DC output voltage by an IGBT
(insulated gate bipolar transistor) power factor correction (PFC) rectifier. The PFC rectifier
shall provide high quality DC power to charge the batteries and power the inverter and shall
have the following characteristics:
1. Input Power Factor Correction (PFC): The PFC rectifier shall be power factor
corrected so as to maintain an input power factor of 0.98 lagging to unity at 75% or above
load levels to ensure generator compatibility and avoid reflected harmonics from
disturbing loads sharing the utility power.
2. Input Harmonic Current Suppression: The PFC rectifier shall produce a sinusoidal
input AC current on each phase with low harmonic content, limiting THD on the UPS
input to below 5%.
3. Battery Charger Current Limiting: The UPS shall be equipped with a system designed
to limit the battery recharge current (from 0.05 C10 to 0.1 C10).
4. Charging Levels: The battery charging circuitry shall be capable of being set for
automatic battery recharge operation, float service, manual battery charge service, and
equalizing or commissioning operation.
5. Intermittent Charging: The battery charge level shall be maintained by an intermittent
charging technique between two values Vfmin and Vfmax very close to the floating
voltage. This technique shall be based on a cycle made up of a short charge period (a
few seconds) from Vfmin to Vfmax followed automatically by a slow discharge period (a
few minutes) from Vfmax to Vfmin. This cycle shall be repeated continuously to maintain
the battery charge level. In this way the battery shall actually be charging only for a small
part of the time, which considerably increases its service life.
6. Temperature Compensated Charging: The battery charger shall be equipped with a
temperature probe to enable temperature compensated charging and adjust the battery
float voltage to compensate for the ambient temperature using a negative temperature
coefficient of 3 mV per cell per degree Celsius at a nominal temperature of 25°C.
7. Battery Capacity: The battery charger shall have sufficient capacity to support a fully
loaded inverter and fully recharge the battery to 95% of its full capacity within 6-8 hours
up to 4 battery cabinets..
B. Inverter
The UPS output shall be derived from a Variable Frequency Pulse Width Modulated (PWM)
IGBT inverter design. The inverter shall be capable of providing the specified precise output
power characteristics while operating over the battery voltage range.
C. Static Bypass – 100% Rated, Continuous Duty
The static bypass transfer switch shall be solid-state, rated for 100% continuous duty without
mechanical contactor device in parallel for higher reliability and consistent response time and
shall operate under the following conditions:
APC – MGE Galaxy 5000 Specification (60Hz) 6 Effective: June 1, 2008 REV X0 JJG
Parallel Module