"UPS: The output power is turned off." after "UPS: Runtime Calibration started."

[Anonymous user]

UPS  SUA1500RMI2U (s/n AS110421xxxx), NMC AP9630 (s/n ZA102400xxxx).

Network Management Card AOS v6.4.0, Smart-UPS & Matrix-UPS APP v6.4.0 (firmware archive "apc_hw05_aos640_sumx640_bootmon108_v4.exe" was used).

We replaced batteries four days ago, and inserted AP9630. Today I've configured AP9630, and started Self-Test.

Six minutes later I've started Runtime Calibration, and UPS has suddenly turned off its output power for some seconds.

How can we prevent such behavior in the future?

The main question - what is more likely: it's a bug of the UPS, or it's a bug of the NMC? Could this be due to batteries?

We have some spare UPS, so I would prefer to replace the problem one, if it makes any sense.

Data log (data.txt):

Smart-UPS 1500 RM
Date Time Vmin Vmax Vout Iout %Wout Freq %Cap Vbat TupsC %VAout
2016-04-12 11:00:43 230.4 230.4 230.4 0.82 17.5 50.00 25.0 25.11 38.7 18.2
2016-04-12 10:50:43 230.4 230.4 229.6 0.77 17.5 50.00 41.0 23.49 37.8 17.5
2016-04-12 10:40:43 230.4 230.4 231.0 0.79 17.5 50.00 59.0 24.03 36.9 17.5
2016-04-12 10:30:43 230.4 230.4 231.0 0.79 17.5 50.00 78.0 24.57 36.0 17.5
2016-04-12 10:20:43 230.4 230.4 229.6 0.79 17.5 50.00 84.0 24.70 35.1 17.5
2016-04-12 10:10:43 230.4 230.4 230.4 0.82 18.2 50.00 99.0 27.27 35.1 18.2 

Event log (event.txt):

Date Time User Event Code

2016-04-12 10:55:37 Device UPS: RFC1628 MIB UPS test completed. 0x3603
2016-04-12 10:55:37 Device UPS: Completed a runtime calibration. 0x0124
2016-04-12 10:14:16 Device UPS: RFC1628 MIB alarm entry removed. 0x3605
2016-04-12 10:14:16 Device UPS: The output power is now turned on. 0x0113
2016-04-12 10:14:12 Device UPS: RFC1628 MIB alarm entry added. 0x3604
2016-04-12 10:14:12 Device UPS: The output power is turned off. 0x0114
2016-04-12 10:14:11 Device UPS: Runtime Calibration started. 0x0123
2016-04-12 10:08:20 Device UPS: RFC1628 MIB UPS test completed. 0x3603
2016-04-12 10:08:20 Device UPS: Self-Test passed. 0x0105
2016-04-12 10:08:05 Device UPS: Self-Test started. 0x0137