SUA2200XLRM3U, Input Voltage issue

[Anonymous user]

Hello All,

We have an SUA2200XLRM3U that is having what appears to be an Input Voltage problem. The unit has one external battery pack, and an AP9617 NMC card installed. We have only recently started using the SNMP card to actively monitor the UPS for anything other than battery capacity and status. The card has been present in the UPS since the original installation in Dec 2007. We recently added Syslogging and active SNMP polling for InputVoltage, OutputVoltage, etc. for the UPSes we have installed, which is when we noticed this issue.

The UPS/SNMP agent is generating undervoltage alerts and syslog messages indicated UPS is switching to battery to compensate. Logged values for Input Voltage are ~106 to 108VAC. Output Voltages generally match the Input Voltage.

However, measured voltage using calibrated meter at supply panel and at supply socket indicates supply voltage is a steady 118VAC.

The UPS's NMC card (AP9617 with v3.7.3 firmware) is reporting a reducing and variable Max Line Voltage & Input Voltage as the load power increases. For example:

Load Power = 010.0 % Watts, Input Voltage = 115.5 to 118.0VAC
Load Power = 051.3 % Watts, Input Voltage = 109.6 to 110.8VAC
Load Power = 077.5 % Watts, Input Voltage = 106.0 to 108.5VAC

We have also noticed that for a period after a Self-Test or Calibration, the logged Input Voltage value will match the measured voltage of the utility feed, and the Output Voltage value will show ~120.0 VAC to ~123.0 VAC. This condition only lasts for ~1 to 2 minutes after the Self-Test or Calibration has been logged as completed, after which the Input and Output Voltage converge to the same value.

We are not sure if this variation in the Input Voltage and Output Voltages as described above is normal behaviour or not. We have not observed similar variations like this in our other UPS installations, but this is the only APC unit we currently have in service in our production data center environment.

The problem that troubles us occurs when the voltage drops below 106VAC. At this voltage level (as recorded by the NMC), the unit switches to Battery until the Voltage increases above an unconfirmed threshold of ~107VAC. Note that this occurs regardless of the Low Transfer V setting, which we currently have at 097, but have also tested at 100, 103, and 106 V. This is happening about once per day, and the battery is usually drained to below 15%, generating yet more alarms.

We have reset, reflashed, and rebooted the NMC card, and have rebooted the UPS with no noticed changes to the observed issue. Physical inspection of the UPS shows no obvious damage. The batteries are not new, but appear to charge and hold a charge without any problems (at least for now).

At this point, we are not sure if the problem is software on the NMC card, a malfunction of the UPS, or a combination of the two. Any guidance from the community is appreciated.

Thanks,

Jaimie
FeatureTel

Serial Num: JS0650001635
Model Num: SUA2200RMXL3U
Batteries: 1x SUA48RMXLBP3U
Date of Mfg: 12/04/2006
Date of Pur: 07/19/2007
Date of Install: 12/29/2007
Firmware Rev: 690.16.D
SNMP/Mgmt: AP9617, PF v3.7.3

Message was edited by: jaimie@featuretel.com