NETA Battery and UPS Systems Testing 2

Question 1

Which UPS topology provides zero transfer time to battery during a utility power outage because the load is always powered by the inverter?

Accepted Answer

Double-conversion (online) UPS

Answer

In a double-conversion online UPS, the load is continuously powered through the rectifier and inverter, so there is no transfer time when utility power fails.

Question 2

During a UPS acceptance test, which specific test verifies that the inverter can independently support the full connected load without utility input?

Accepted Answer

Battery runtime (discharge) test

Answer

The battery runtime test disconnects utility input and verifies the UPS inverter can sustain the rated load for the specified backup duration using only stored battery energy.

Question 3

What output power quality parameter should be measured at the UPS output terminals during load acceptance testing to assess the quality of power delivered to critical loads?

Accepted Answer

Output voltage regulation and total harmonic distortion (THD)

Answer

Output voltage regulation and THD characterize the quality of power delivered to critical loads, ensuring the UPS meets the clean power specifications required by sensitive equipment.

Question 4

When the static bypass switch in a UPS system transfers the load, where does the load power come from?

Accepted Answer

Utility (bypass) power, bypassing the rectifier and inverter

Answer

The static bypass switch transfers the load directly to utility power, bypassing the rectifier, battery, and inverter to allow UPS maintenance or to handle overload conditions.

Question 5

Failure of which component in the UPS rectifier/charger section would most likely cause excessive AC ripple voltage on the DC bus?

Accepted Answer

DC filter capacitors

Answer

DC filter capacitors smooth the pulsating DC output of the rectifier; when they degrade or fail, AC ripple passes through to the DC bus and battery.

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

NETA Battery and UPS Systems Testing 2