Undervoltage protection for a UPS

[Cantonellis]

25. Undervoltage protection for a UPS should:
A- Inhibit the ATS
B- Open the AC input breaker
C- Start the generator
D- Open the inverter input breaker

Does anyone know the answer to this question? I thought they might be referring to DC Undervoltage to open the inverter input breaker (D) since one of the electrical tests for a UPS is: "Test dc undervoltage trip level on inverter input breaker" (NETA-ATS 7.222.2.B.4). According to testguy, that was not the correct answer.

[mwallace]

25. Undervoltage protection for a UPS should:
A- Inhibit the ATS
B- Open the AC input breaker
C- Start the generator
D- Open the inverter input breaker

Does anyone know the answer to this question? I thought they might be referring to DC Undervoltage to open the inverter input breaker (D) since one of the electrical tests for a UPS is: "Test dc undervoltage trip level on inverter input breaker" (NETA-ATS 7.222.2.B.4). According to testguy, that was not the correct answer.

According to NETA 7.22.2.D.4 upon DC undervoltage, shall trip the inverter input breaker.