120 to 110 Volt Converter/Regulator/UPS

[jscaufi]

I have been assisting someone with a failures of electronic boards in equipment made overseas. The equipment is rated at 110 VAC +/- 10%. Monitoring reveals the voltage to the site is well within recommended limits for 120 volt service 114-126 volts, most of the time around 121-123 volts. This is over the limit for the equipment rating of course but probably does not cause damage to the equipment. However, in order to satisfy the vendor, the customer would like to get the supply voltage to the electronic equipment to the 110 volt level. The 30 or so sensors that have the failing boards are supplied by an APC Smart-UPS 3000. It's output is 120 volts. Is there a voltage regulator, UPS or converter that takes 120 volt nominal voltage and convert it to 110 volts? I could use a variac I suppose but I would like to see it maintained at 110 volts like an online double conversion UPS would do for 120 volt systems.

thanks
j

 

[ScottyUK]

Cheapest way is going to be an auto-transformer with 110V and 120V taps.

You might want to look at the output of the UPS when it is in battery mode and see if you are getting a sinusoidal output or a square / quasi-square output. That would be my immediate concern with a cheap UPS.


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If we learn from our mistakes I'm getting a great education!

 

[TheBlacksmith]

Last time I ran into this problem we changed the taps on the transformer supplying the facility to drop the output 10 volts. Worked like a champ.

 

[potteryshard]

I think I'd be very concerned with integrity of the vendor... 110 V is a application voltage and is intended solely to provide a voltage drop cushion between the source (120 V per ANSI) and the end use. If they are claiming that the source must be 110 V, then this product is not merchantable in this country.

 

[karalahana]

is it possible that 10 volt drops between source and equipment input ? Is not it a bit large number ? I guess you mean if an equipment needs 110 volt into it ,it must be fed from a 120 volt source (No-load or full load voltage ? ) true?

 

[jscaufi]

Thanks for the responses. Since my post I have downloaded power monitors at the site. They had performed some testing of compressors having them come on simultaneously. This dropped the voltage enough to cause the UPS to transfer to battery. When it did, it caused slight voltage swells after the intial voltage sag to 127-128 volt range.

I have also talked to the Dutch vendor. They have confirmed that this equipment is rated 110 VAC +/- 10%. The facility is fed from a single phase transformer standard U.S. service entrance votlage of 120 volts. That means if the delivery voltage is slightly over nominal, let's say 122 volts (which is perfectly acceptable) it is over the rating of the equipment. I am not sure that would be enough to damage components in this equipment. Hence my search for a relatively inexpensive fix at the point where these sensors are supplied voltage, not the entire facility. If the taps were to be changed at the transformer (if there were taps available) then the other equipment rated at 120 volts would be seeing low voltage.

j

 

[ScottyUK]

Like I said in the first post, feed your loads through an autotransformer. Cheap, simple, easy, readily available.

Doesn't address the problem of the UPS transferring onto battery, but the most likely causes of that are either an under-sized supply coming in to your premisies or under-sized cabling within your premises. If the UPS transferring to battery is a problem you need to address it separately.


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If we learn from our mistakes I'm getting a great education!

 

[rbulsara]

If you are in the USA, the auto-transformers, ScottyUK is referring to, are more commonly known as buck/boost transformers in the USA.

Rafiq Bulsara

http://www.srengineersct.com

 

[ScottyUK]

Thanks Rafiq!


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If we learn from our mistakes I'm getting a great education!