NMC reported Input Voltage Questions

[Anonymous user]

Hello All,

If someone can answer these questions, I would greatly appreciate it.

What is the relationship between the NMC's reported Input Voltage and the Utility feeds measured voltage? Shouldn't the values be roughly the same, +/- 5%?
What would cause a situation where the NMC's reported Input Voltage would be significantly less than the Utility feeds voltage measured at the plug?
The NMC's Input Voltage decreases as the UPS load increases. Is this normal?

We have an SUA2200XLRM3U +1 SUA48RMXLBP3U, with an AP9617 NMC.

Thanks,

Jaimie

[Anonymous user]

Thanks for the reply.

I've attached the event and data logs. I stripped out System messages related to DNS, User login, e-mail, etc. from the event log to reduce it's size.

The logs go all the way back to the original installation in 2007. The input voltage problem appears to have been around since the beginning, but was never noticed since I've only recently started actively monitoring the UPS vital stats (Input Voltage, Output Voltage, Load, and Battery Capacity) using SNMP queries from an Solarwinds Orion NMS platform.

The UPS was installed as a "last line of defense" unit in a Colo that already provides filtered, UPS+Generator backed up power. The Utility feed for the UPS is a direct bypass feed provided by the colo specifically for this application.

Thanks,

Jaimie

[BillP]

The NMC reports the values provided by the CPU in the Smart-UPS. It is possible that the UPS is incorrectly evaluating voltage and reporting it to the NMC.

This can be tested a few different ways:

1) Install PowerChute Business Edition Agent and see what the software reports for these voltages. Like the NMC, the software reports what is provided by the UPS.

2) Try another known-good NMC and view reported voltages.


Also, to answer your other question: Yes, all other things being equal on a given circuit, voltage does decrease as load increases.

[Anonymous user · Accepted solution]

Hello All,

If someone can answer these questions, I would greatly appreciate it.

What is the relationship between the NMC's reported Input Voltage and the Utility feeds measured voltage? Shouldn't the values be roughly the same, +/- 5%?
What would cause a situation where the NMC's reported Input Voltage would be significantly less than the Utility feeds voltage measured at the plug?
The NMC's Input Voltage decreases as the UPS load increases. Is this normal?

We have an SUA2200XLRM3U +1 SUA48RMXLBP3U, with an AP9617 NMC.

Thanks,

Jaimie