Townshend
Student
- Oct 8, 2022
- 5
At my house I have an 1100VA UPS (WB-OVRC-UPS-1100-1) where I have been encountering issues since Day 1 back in March. Periodically for periods of time the UPS will alternate rapidly between line and battery, about a second at a time (attached is a video of the occurrence). I had an electrician run a 20A dedicated circuit back to the panel to see if that resolved the issue, which it did not. I tested on other outlets/circuits throughout the house with no luck. At the time, the only possible connection I could make was the morning after it rained the issue seemed to occur. Not 100% of the time but that seemed to correlate and wondered if there was interference from the sump pump. I then tested by turning off every circuit in the house except for the circuit to the UPS, again, no luck.
I then replaced the UPS with a brand new one in case it was an issue with the UPS itself. It seemed to be pretty solid for nearly a month and then the issue would periodically happen again. Coincidentally during this time it was also nice and dryer here although was not positive that had any relevance. Eventually it began occurring with some regularity and to the point of near constant and replaced the UPS with a new one for a third time.
The third one continued the trend of near constant alternation between line and battery. At this point, I got a multimeter and monitored the frequency and voltage. Frequency ranged from 59.89-60.00 and voltage from 122-125, even during episodes where the UPS would alternate. At this point I began to look at a greater scale. I had my utility have a monitoring device at the meter for about a month and they noted no anomalies. I then took the UPS to another house a few miles down the road (as with most residential, single phase), which had the same issue. I then took to a local Starbucks which has a 3 phase pad mount. UPS never went away from line power during a 15 minute test, at my and another residence the alternation would occur almost immediately. I then went to a local school and tested there, also a 3-phase padmount feeding to the building. Again, 15-minute test, no issues. Tested at a 3rd residence, 1-phase, issues occurred. Local gas station, 3-phase open delta bank, had issues. Last, McDonalds 3-phase padmount, ran without issue for 15-minutes here as well.
I am not an electrician and learning and testing as I look to determine the root cause. A few questions:
1. The only consistent success has been the 3-phase padmount electrical feed. Obviously this is not feasible to my home, but would there be a specific reason the UPS would function without issue in this scenario versus 1-phase or even 3-phase open delta?
2. Since voltage and frequency appear within spec, the cause seems to be narrowing down to a waveform issue as it relates to total harmonic distortion (THD). Could I be on the correct track here?
3. If so, any recommendation on a Harmonic Analyzer or device to view the waveform and determine what might be out of spec to trigger the alternation? In looking around these are quite expensive. Are there professionals that I can look for that may have one I can hire or a recommendation of where to rent one?
4. Finally, if anyone has seen a similar scenario as mine and has any suggestions on ways to mitigate? Better grounding or an alternate method? The simple solution might simply be to switch to a less sensitive UPS, however, at this point it's also worth digging into for the educational aspect.
Thank You!
I then replaced the UPS with a brand new one in case it was an issue with the UPS itself. It seemed to be pretty solid for nearly a month and then the issue would periodically happen again. Coincidentally during this time it was also nice and dryer here although was not positive that had any relevance. Eventually it began occurring with some regularity and to the point of near constant and replaced the UPS with a new one for a third time.
The third one continued the trend of near constant alternation between line and battery. At this point, I got a multimeter and monitored the frequency and voltage. Frequency ranged from 59.89-60.00 and voltage from 122-125, even during episodes where the UPS would alternate. At this point I began to look at a greater scale. I had my utility have a monitoring device at the meter for about a month and they noted no anomalies. I then took the UPS to another house a few miles down the road (as with most residential, single phase), which had the same issue. I then took to a local Starbucks which has a 3 phase pad mount. UPS never went away from line power during a 15 minute test, at my and another residence the alternation would occur almost immediately. I then went to a local school and tested there, also a 3-phase padmount feeding to the building. Again, 15-minute test, no issues. Tested at a 3rd residence, 1-phase, issues occurred. Local gas station, 3-phase open delta bank, had issues. Last, McDonalds 3-phase padmount, ran without issue for 15-minutes here as well.
I am not an electrician and learning and testing as I look to determine the root cause. A few questions:
1. The only consistent success has been the 3-phase padmount electrical feed. Obviously this is not feasible to my home, but would there be a specific reason the UPS would function without issue in this scenario versus 1-phase or even 3-phase open delta?
2. Since voltage and frequency appear within spec, the cause seems to be narrowing down to a waveform issue as it relates to total harmonic distortion (THD). Could I be on the correct track here?
3. If so, any recommendation on a Harmonic Analyzer or device to view the waveform and determine what might be out of spec to trigger the alternation? In looking around these are quite expensive. Are there professionals that I can look for that may have one I can hire or a recommendation of where to rent one?
4. Finally, if anyone has seen a similar scenario as mine and has any suggestions on ways to mitigate? Better grounding or an alternate method? The simple solution might simply be to switch to a less sensitive UPS, however, at this point it's also worth digging into for the educational aspect.
Thank You!
