ups malfuntioning at 204volts

[highpowered]

I have a client whos UPS servers are going onto battery backup it seems because the voltage is low. the voltage is at 204v. The main power coming to the panel is 480v. The transformer converts it to 208/120v 3 phase. The main panel is somewhat unbalanced but theres not much I can do to balance it perfectly. I was thinking a buck boost transformer on the circuit and step it up back too 208v? Honestly He needs a new panel and transformer but for now he needs his servers running. Any solutions?
Thanks

 

[ron]

The UPS's shouldn't be going into battery mode with only a 2% voltage drop. The UPS needs to be maintained. Typically it will tollerate 10% before going into battery / inverter mode.

 

[brian john]

And if it was a low voltage issue you could change the taps settings in the transformer to boost the voltage.

But there are draw backs to this as typically low voltage is usually not consistently low, so if voltage goes up, say at night or weekends then you can have an over-voltage condition,

As noted UPS are generally 10% under-voltage but many are 5% over-voltage

 

[don_resqcapt19]

Are the UPSs single phase units that are looking for 240 volts?

 

[highpowered]

And if it was a low voltage issue you could change the taps settings in the transformer to boost the voltage.

But there are draw backs to this as typically low voltage is usually not consistently low, so if voltage goes up, say at night or weekends then you can have an over-voltage condition,

As noted UPS are generally 10% under-voltage but many are 5% over-voltage

the company has a UPS tech on payroll and he says its the voltage? I only bring the power to these racks I have no idea how to troubleshoot once it passes through the cleaner. I used infrared on this circuit and everything is running hot. The nuetral is returning almost the same amount of power and heat the conductors are. its pulling 17 amps on all lines (hot and nuetral) on a 20 amp 208 volt 2 pole circuit. Any thoughts?

 

[highpowered]

Are the UPSs single phase units that are looking for 240 volts?[/QU

maybe? They have a tech on payroll he should of spotted that no?

 

[hillbilly1]

Depending on the transformer, it may have adjustable taps to increase the voltage, but as others have said, 204 volts should not be kicking it to battery. Does it go to battery at regular intervals, around 10-15 seconds apart? If so you probably have a printer plugged into one of the output circuits, some printers have heaters to keep the ink warm, and draw pulses of around 15 amps for just a couple of seconds.

 

[__dan]

the company has a UPS tech on payroll and he says its the voltage? I only bring the power to these racks I have no idea how to troubleshoot once it passes through the cleaner. I used infrared on this circuit and everything is running hot. The nuetral is returning almost the same amount of power and heat the conductors are. its pulling 17 amps on all lines (hot and nuetral) on a 20 amp 208 volt 2 pole circuit. Any thoughts?

If you measure right at the transformer, feeding it 480 v and getting 204 v, you could be one tap low and raising it 2.5% would put you at 209 v. If the primary side 480 v is low, the low voltage problem is upstream, not at the transformer taps. If the unit is rated 208 and you are feeding it 204v solid under load, 204v is not low considering voltage drop downstream, loaded. Not great but not low.

If the unit draws 17 amps L to L at 208v and 17 amps on the neutral, the high neutral current indicates high harmonic content of the load. Today's IT equipment generally has high quality, low harmonic, power supplies. I usually only see cheap power supplies now on the display panels, if your load was all monitor screens. Modern hardware generally is pretty good.

Try to measure neutral current relative to the expected neutral imbalance current, both line and load side of the UPS, to try to determne if the high harmonic content load is after the UPS or is the UPS itself internally.

Most electronic stuff, UPS's included, have electrolytic type capacitors that dry out and can have a service lifetime in a UPS of 5 to 8 years. If the caps are out of spec and distorting the input or output waveform, it could easily be a problem internal to the UPS. I would assume factory service necessary to diagnose and change something like that. Never heard of an "onsite UPS tech".

The UPS display may or may not give you more information, load balance, power factor of the load, reason for going to battery. If the power factor is bad, I would again suspect an internal UPS problem. The electrolytic caps are a wear item.

If you have bad power factor and high harmonic content due to the UPS, it indicates a problem internal to the UPS. If it is caused by the load on the UPS, the UPS could be suffering from it.

As noted above, the UPS's require annual or so maintenance.

 

[gar]

120924-1956 EDT

Insufficient information. The 208 seems to imply a 3 phase wye source. A later post indicated a two pole breaker. From this one could expect 208 between the two poles. More information is needed. What is the intended input to the UPS? 240 or 208?

.

 

[kwired]

If 120/208 volt and only two phases and neutral - it would be expected to see approximately same current on neutral if both phases are about same current. 120/240 single phase - each line would cancel and neutral would only see imbalance. This is all before considering any harmonics.

I also think it is worth looking into whether or not the UPS is in fact looking for 240 volts instead of 208.

 

[highpowered]

If 120/208 volt and only two phases and neutral - it would be expected to see approximately same current on neutral if both phases are about same current. 120/240 single phase - each line would cancel and neutral would only see imbalance. This is all before considering any harmonics.

I also think it is worth looking into whether or not the UPS is in fact looking for 240 volts instead of 208.

the UPS is at the lowest acceptable voltage setting -208v. yes its is 208 being fed into the UPS on a 2 pole 20 amp breaker. The low voltage reading is coming on every night between 215am-415 am. This throws me off because it is not even close to peak time for power consumption.

 

[highpowered]

If you measure right at the transformer, feeding it 480 v and getting 204 v, you could be one tap low and raising it 2.5% would put you at 209 v. If the primary side 480 v is low, the low voltage problem is upstream, not at the transformer taps. If the unit is rated 208 and you are feeding it 204v solid under load, 204v is not low considering voltage drop downstream, loaded. Not great but not low.

If the unit draws 17 amps L to L at 208v and 17 amps on the neutral, the high neutral current indicates high harmonic content of the load. Today's IT equipment generally has high quality, low harmonic, power supplies. I usually only see cheap power supplies now on the display panels, if your load was all monitor screens. Modern hardware generally is pretty good.

Try to measure neutral current relative to the expected neutral imbalance current, both line and load side of the UPS, to try to determne if the high harmonic content load is after the UPS or is the UPS itself internally.

Most electronic stuff, UPS's included, have electrolytic type capacitors that dry out and can have a service lifetime in a UPS of 5 to 8 years. If the caps are out of spec and distorting the input or output waveform, it could easily be a problem internal to the UPS. I would assume factory service necessary to diagnose and change something like that. Never heard of an "onsite UPS tech".

The UPS display may or may not give you more information, load balance, power factor of the load, reason for going to battery. If the power factor is bad, I would again suspect an internal UPS problem. The electrolytic caps are a wear item.

If you have bad power factor and high harmonic content due to the UPS, it indicates a problem internal to the UPS. If it is caused by the load on the UPS, the UPS could be suffering from it.

As noted above, the UPS's require annual or so maintenance.

thank you . The UPS tech just told me the low voltage reading goes on between 215am and 415am? his system records the faults i guess

 

[highpowered]

Depending on the transformer, it may have adjustable taps to increase the voltage, but as others have said, 204 volts should not be kicking it to battery. Does it go to battery at regular intervals, around 10-15 seconds apart? If so you probably have a printer plugged into one of the output circuits, some printers have heaters to keep the ink warm, and draw pulses of around 15 amps for just a couple of seconds.

I will check the output circuitas today. The computer logs low voltage malfunction between 215-415am everyday. I dont know why at low peak power time it does that

 

[gar]

120925-1046 EDT

If the UPS is really wired for 208 as the nominal input, and it triggers at 204 V, then the UPS has a problem.

Why would you expect the source voltage to be high in the middle of the night? On my home voltage I have one sample plot, quickly available, where the night voltage was about 1 V less than the maximum during the day. It all depends on what the power company voltage regulators do.

.

 

[texie]

Have you considered something as simple as a motor or A/C unit cycling that is connected to the same feeder or panel? Maybe the source for the UPS is not "stiff" enough. I have seen this and there was nothing wrong with the UPS.

 

[kwired]

Is the 208 volt setting an actual trip point or the min setting with a tolerance band around the 208 setting?

If load is low during that time period the POCO regulators may be stepping voltage down because the load is down.

Have you recorded actual voltage in any way at the time this is happening?

Still sounds to me like you have voltage in an acceptable range but your UPS is not able to be set as low as what is acceptable, was likely designed for 120/240 more so than 120/208, and is operating at the bottom of what is acceptable @ 240 volts.

 

[highpowered]

Have you considered something as simple as a motor or A/C unit cycling that is connected to the same feeder or panel? Maybe the source for the UPS is not "stiff" enough. I have seen this and there was nothing wrong with the UPS.

that is what the tech is saying theres a volt problem. My problem is if they spend $15,000 to upgrade there transformer and panel and the UPS is still malfunctioning they are going to be a lil pissed off. there is alot of stuff connected to the panel. There is another UPS connected to the panel as well and I believe it is functioning properly.

 

[__dan]

Have you considered something as simple as a motor or A/C unit cycling that is connected to the same feeder or panel? Maybe the source for the UPS is not "stiff" enough. I have seen this and there was nothing wrong with the UPS.

that is what the tech is saying theres a volt problem. My problem is if they spend $15,000 to upgrade there transformer and panel and the UPS is still malfunctioning they are going to be a lil pissed off. there is alot of stuff connected to the panel. There is another UPS connected to the panel as well and I believe it is functioning properly.

The momentary voltage dip from the A/C unit starting is a good bet. I've seen it with those cheap disposable UPS units combined with aged batteries. The unit would swap to battery when the A/C unit starts, and due to the worn out batteries it was like having air between the battery terminals. The load would go down because of the UPS swapping to worn out batteries.

A voltage blip at the same approximate time in the very early morning sounds like a utility switching transient. If so and the UPS unit has good batteries, it is doing its job.

It would help to post a model number for the UPS to see if it's a type with the inverter always on, double conversion, or a type that is on utility and swaps to battery for disturbances, line interactive.

If the existing transformer and panel is loaded but in good shape, I would look at leaving it there and adding something just for the additional load, maybe a smaller 480v feed and stepdown transformer just for the critical loads, if the 480 is the good place to get the feed. It sounds like your IT load is between 5 and 10 kva and the dedicated circuit may be what the UPS tech wants you to give him. It may not cure the problem you're having, but business is about giving the customer what they want.

 

[gar]

120925-1950 EDT

highpowered:

You need to find out what is the UPS nominal input voltage rating, and where the trip threshold is relative to this rating. If the UPS is designed for a nominal 240 input then you will have a problem running on a 208 supply.

.

 

[highpowered]

The momentary voltage dip from the A/C unit starting is a good bet. I've seen it with those cheap disposable UPS units combined with aged batteries. The unit would swap to battery when the A/C unit starts, and due to the worn out batteries it was like having air between the battery terminals. The load would go down because of the UPS swapping to worn out batteries.

A voltage blip at the same approximate time in the very early morning sounds like a utility switching transient. If so and the UPS unit has good batteries, it is doing its job.

It would help to post a model number for the UPS to see if it's a type with the inverter always on, double conversion, or a type that is on utility and swaps to battery for disturbances, line interactive.

If the existing transformer and panel is loaded but in good shape, I would look at leaving it there and adding something just for the additional load, maybe a smaller 480v feed and stepdown transformer just for the critical loads, if the 480 is the good place to get the feed. It sounds like your IT load is between 5 and 10 kva and the dedicated circuit may be what the UPS tech wants you to give him. It may not cure the problem you're having, but business is about giving the customer what they want.

Ok met with the tech guy today he has a detailed version of events. He told me 208v but infact it is on a 208 panel the voltage is 120v. At the source where the UPS plugs in it reads 114v. coming out of the UPS to feed the strip all the servers are on it reads 108v. He has downloaded more firmware so he can adjust the voltage to 106v minimum. He refuses to believe his equipment is malfuntioning even though the battery will not charge to 100%. It only charges to 99.2%. I apologize I did not get the model of the UPS. When he does a system check it says its getting 117v. When I check it is 114v at source and 107.7 coming out of the ups feeding the servers? im proposing a sub panel in the server room as the circuit has a long way to travel to the panel its in. They have them on 30amp circuits combineing nuetral and ground at the main panel nuetral bar? My opinion is His UPS needs replaced as the brand new one next to it is functioning fine off of the same power source.