Uninterruptable Power Supplies ("UPS")

Backup generators are great but they take time to turn on, ramp up, and take a load. The fastest generators are NFPA110-certified and take on a load within 10 seconds. Other generators normally require about 30 – 45 seconds to ramp up and take on a load. If you have equipment that cannot go down even for a few seconds (computers, critical medical equipment), you require an uninterruptable power supply, or “UPS.”

UPS systems will typically feed a load for up to 5 minutes. This allows time for the backup generators to start and ramp up, or time to take appropriate action such as a controlled shutdown of the equipment. 

There are two subtypes of UPS with significantly different price points. The difference between the two relates to how it deals with incoming power quality issues. 

Dual-conversion UPS systems clean up power quality issues coming in from the grid by converting the incoming AC grid power to DC, storing it momentarily in the battery, and then converting it back to clean AC.

Unitary conversion does not clean up incoming power. Instead, the UPS sits on the plant AC bus and keeps charged as needed. When there is an outage, the UPS converts the battery DC to AC and feeds the plant’s AC bus – the incoming grid does not pass through the UPS.