Required Input Frequency of SUA2200RMI2U

[Anonymous user]

We have a SUA2200RMI2U UPS that when operational runs with an input frequency of 50Hz. We recently experienced a power outage and the UPS went onto battery and within 2 minutes our back up generator was functional however the UPS failed to return from battery and go back to mains power. When checking with our electrician the reason for this was due to the ouput frequency from the generator being between 51-52 Hz and that the UPS was not able to compensate for this. On looking on the APC website the UPS in question should be able to handle the variation in frequency of between +/- 3 Hz (auto sensing) however is there anything else we would need to do to configure the UPS or is it already in the auto sensing mode?

http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SUA2200RMI2U

Apologies if my explaination doesn't sound right.....I'm not an electrician.

thanks

[Anonymous user]

Hi.

The sensitivity configured within the Utility Line Settings is High. Should I look to lower this?

[TheNotoriousKMP_apc]

Aled,

Have you tried adjusting the sensitivity of the UPS to a lower state than what it is currently in?

If it's not a frequency drift that's forcing the UPS on battery, it's possible it's excessive harmonic distortion.

You could also ask the electrician to put an oscilloscope on the output of the generator to see how distorted the sine wave is/isn't.

[Anonymous user]

Is there any information in relation to the sensitivity setting of the UPS'? Been having a trawl of the APC website but can't find anythign conclusive. Does High Sensitivity mean + or - 1Hz, Medium + - 2Hz etc

many thanks

[TheNotoriousKMP_apc]

Run the generator test again if possible, this time with the UPS set to Medium. If it still doesn't work, set it to Low. If at that point it doesn't work, re-consult the electrician to look at the sine wave output of the generator feeding the UPS.

[TheNotoriousKMP_apc]

Aled,

Most of the sensitivity features have to do with AVR thresholds and allowing for excessive distortion on the sine wave, within a limitation.

Hopefully this Knowledge Base article can help:

http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=62

[Anonymous user · Accepted solution]

aledrob wrote:
We have a SUA2200RMI2U UPS that when operational runs with an input frequency of 50Hz. We recently experienced a power outage and the UPS went onto battery and within 2 minutes our back up generator was functional however the UPS failed to return from battery and go back to mains power. When checking with our electrician the reason for this was due to the ouput frequency from the generator being between 51-52 Hz and that the UPS was not able to compensate for this. On looking on the APC website the UPS in question should be able to handle the variation in frequency of between +/- 3 Hz (auto sensing) however is there anything else we would need to do to configure the UPS or is it already in the auto sensing mode?

http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SUA2200RMI2U

Apologies if my explaination doesn't sound right.....I'm not an electrician.

thanks

I'm not sure what the freq. tolerance allowable on the APC UPS, however it is not adjustable. What is the load level and what size is the generator?

This maybe helpful for you, however, it won't help you if the generator isn't adequately sized.
http://www.adec.edu/nsf/generator.html