Ferroresonate Transformer Application
Ferroresonate Transformer Application
(OP)
Looking for some technical insight or a pointer to better understand a problem recently.
A customer has a UPS (on off-line ferroresonate type) providing backup power for a control system. Because of power quality issues at another customer site, they have installed a power conditioning transformer at the input of this UPS (the transformer made by SOLA/Hevi-Duti and is also a ferroresonate type device).
The customer has experienced noise/spikes/harmonics between the UPS and the xfmer causing the UPS to switch to battery power constantly. Basically copied a solution at one site to this application without fully investigating the equipment involved.
Both the UPS manufacturer and the xfmer techs stated that a power conditioning transformer should not feed a UPS of this type. The combination of a high impedance device feeding another high impedance device was causing the issue.
The power conditioning xfmer was removed (replace by a general purpose xfmer) and no problems have been detected.
Neither vendor could supply any tech data on why this application doesn't work. Could someone elaborate?
A customer has a UPS (on off-line ferroresonate type) providing backup power for a control system. Because of power quality issues at another customer site, they have installed a power conditioning transformer at the input of this UPS (the transformer made by SOLA/Hevi-Duti and is also a ferroresonate type device).
The customer has experienced noise/spikes/harmonics between the UPS and the xfmer causing the UPS to switch to battery power constantly. Basically copied a solution at one site to this application without fully investigating the equipment involved.
Both the UPS manufacturer and the xfmer techs stated that a power conditioning transformer should not feed a UPS of this type. The combination of a high impedance device feeding another high impedance device was causing the issue.
The power conditioning xfmer was removed (replace by a general purpose xfmer) and no problems have been detected.
Neither vendor could supply any tech data on why this application doesn't work. Could someone elaborate?






RE: Ferroresonate Transformer Application
RE: Ferroresonate Transformer Application
http://www.elect-spec.com/klr_z.htm
or
http://www.thomasregister.com
and type Transformers: Ferroresonant under Product or Service, which will return 80 companies to approach to
RE: Ferroresonate Transformer Application
Looking for someone to provide to tech detail on what might be happening.
RE: Ferroresonate Transformer Application
You may be hard pressed to find published documentation that deals with “cascaded” ferroresonant AC-power devices. The problem may be better described as a higher-impedance source—the SOLA—not working well serving as what it sees as a lower-impedance load—the UPS.
The UPS may have two problems with this arrangement. The lower impedance may be a “nonlinear” load seen by the SOLA varies at difference points on the upstream [imperfect] sinusoidal voltage the SOLA presents. The UPS’ power-handling circuitry may not work well with a limp source, or it may be [possibly on a sub-cycle basis] its integral voltage-sensing circuitry interprets the source waveform [or a part of it] as being out of range of its acceptable limits.
At any rate, ferroresonant-AC devices generally are happiest seeing a stiff source, while serving a much-less-stiff load. In some cases, the “weak spot” is voltage crossover distortion on the upstream-transformer secondary, that is sensed as something like a frequency deviation by the UPS, even though RMS-AC measurements with a DMM indicate everything is fine.
Sometimes a UPS can report failure information that could provide clues.
RE: Ferroresonate Transformer Application
http://www.lamarchemfg.com/PDF/A36D.pdf
where load sharing/paralleling is addressed
The reason for this is the output quality can vary and appropriate filtering is required to minimize the mutual interference and the harmonic waveform synthesis on the output. This is however not all if there are nonlinear loads. Then, additional filtering or load caused harmonic mitigation will be required. Certain technological aspects and methodology the manufacturer uses may be proprietary.
RE: Ferroresonate Transformer Application
The issue isn't paralleling, it is 'series-ing' where one device is feeding the other. The situation is rather different.
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RE: Ferroresonate Transformer Application
RE: Ferroresonate Transformer Application
With out the SOLA power conditioning transformer feeding the UPS, the unit seems to be operating fine under full load. Only complaint is flatness in the output voltage waveform of the UPS at zero crossing. I believe this is typical of this type of UPS.
I appricate the feedback.
RE: Ferroresonate Transformer Application
http://www.sola-hevi-duty.com/
for product categories
It appears that there are:
1. Sola UPSs
2. Sola Power Conditioners
3. Sola Transformers
The above postings suggest that there might have been interaction between nonlinear elements within the UPS input and within "so-called Power Conditioning Transformer" output side on the UPS input side.
RE: Ferroresonate Transformer Application
By the way, Busbar is right on the money. Not a lot of study has been done because there would be little reason to do what they did. Except of course, as in this case, it accidentally ended up that way.
"Venditori de oleum-vipera non vigere excordis populi"
RE: Ferroresonate Transformer Application
RE: Ferroresonate Transformer Application
I had a similar result with a 5kVA ferro UPS feeding a 1.5 kVA on line UPS. I was told that tank circuit (ie capacitors that run the ferro xformer at full saturation) cause the output of the ferro xformer to resonate when it's supplying an inductive load (ie on-line UPS). This causes the on line UPS to transfer to battery operation and effectively disconnecting itself from the output of ferro-xformer.
Guess what happens to the ferro UPS output next... it stabilizes and therefore the on line UPS tries to return online only to repeat the whole scenario again.
Put a scope on the output of your ferro line conditioner and watch the funny things happen.
RE: Ferroresonate Transformer Application
Funny thing ... different rig with a slightly different application. Same ferro xfmer but feeding an on-line type UPS (rectifier-inverter scheme). The opposite problems are happening. Under light load, the UPS will not sync with the incomming feed. Once the unit is loaded above 30%, the alarms go away and all is running fine.
My thinking is that the rectifier isn't providing the ferro enough current draw (inverter chopping the waveform) for it to regulate properly.
RE: Ferroresonate Transformer Application
The UPS would trip out due to either under or overvoltage. The manufacturer had a fix, replace a voltage regulator board in the UPS.
RE: Ferroresonate Transformer Application
The combination of a high impedance device feeding another high impedance device was causing the issue.
///The high impedance source would cause a high voltage drop. Is that the case? This is what can be measured.\\\