sola MCR power conditionner 5

[mohpower]

hello,

SOLA HEAVY DUTY is the manufacturer of MCR power conditionner based on regulating output voltage by using the concept of ferroresonance. and also it is used as Harmonic filter (as it was indicated by SOLA). my question is how the MCR eliminates harmonics?.

thanks

mohpower

 

[jraef]

It doesn't have an additional filter, ferroresonant transformers are inherent filters. Inefficient as all heck, but the harmonics from the load side don't get transferred back to the line, they can't by nature of how the ferroresonant transformer works. Current harmonics are dissipated as heat in the transformer. So Sola came up with this idea of marketing them as "filters" a few years ago.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[jraef]

I should add that the output waveform of the Ferro is ugly, full of harmonics itself. It is essentially a flat topped sine wave, almost a square wave. When they refer to them as "filters" they are only meaning that any additional harmonics created by non-linear loads on the load side of the ferro will not be seen on the line side.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[itsmoked]

jraef do you have that backwards? I thought the idea of using a Sola was to assure the load got a non-changing voltage output regardless (within reason) of what was going on on the supply side. ??

And yes you could fry eggs on them.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[mohpower]

how to you explain the presence of capacitor within those ferroresonance transformers. what is really the purpose of adding them to the transformer?

thanks

moh power

 

[Skogsgurra]

A ferro-resonance transformer is a secondary that is tuned to the mains frequency. The capacitors are there to resonate with the secondary winding.

The secondary is weakly coupled to the primary via the magnetic flux. The weak coupling is achieved by means of a magnetic shunt that shorts out part of the flux.

The resonance brings the secondary circuit into a "violent" swinging. So violent that magnetic sturation of the secondary core occurs. The saturation stops any further increase in amplitude, which means that the output voltage stays constant and also that the output voltage from a ferro-resonant transformer has flat (clipped) tops. The iron works somewhat like an "AC zener diode".

I have some recordings showing the action. Shall try to make them available.


Gunnar Englund

http://www.gke.org

 

[mohpower]

thanks for clarifications.

skogsgurra, could you please send me your recording showing the result.

regards

mohpower

 

[Skogsgurra]

This is what the output voltage from a magnet stabilizer looks like when input power is removed.

First, you see the normal output voltage. Rather nasty shape. Then, the input voltage is removed (red line indicates trig point) and the output voltage first gets more sine-like and then the amplitude decreases at the same time as the frequency decreases.

What you see after the power was removed is the resonant circuit oscillating and delivering energy to the load. The fact that frequency decreases is because the equivalent inductivity of the core increases when it gets out of saturation.

Gunnar Englund

http://www.gke.org

 

[itsmoked]

Nice description Gunnar. And picture!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Skogsgurra]

Thanks Smoked! You teached me...

Gunnar Englund

http://www.gke.org

 

[mohpower]

hello Guys,
this is what I received from SOLA technical service on my question so what do you think???

"Sola/Hevi-Duty’s MCR Power Conditioners will hold output voltages to +/- 3% or les with input variations as greater as +/-15% (115VAC+/-15% or 120VAC). Units operated at less than rated load will maintain approximately +/- 3% regulation over a wider input line voltage variation.

Sola /Hevi –Duty power conditioners include a resonant circuit that is energized whether or not it is serving load. Sola‘s ferrosonant power conditioners are very stable the input current at no load or light load may run 50% or more of the full primary current

What is exactly is Ferroresonance?

Ferroresonace is the property of a transformer design in which the transformer contains two separated magnetic paths with limited coupling between them. The output contains a parallel resonant tank circuit and draws power from the primary to replace power delivered to the load that “resonance” in ferroresonance is similar to that in linear circuits with series or parallel inductors and capacitors, where the impedance peaks at a particular frequency (50Hz.-60 Hz.) in a nonlinear circuit, such as Sola’s ferroresonats transformers, “resonance” is used to reduce changes in supply voltage to provide a more consistent voltage to the load.



Regarding your question about how the harmonics are eliminated in the MCR Power Conditioner basically we added a neutralizing coil, this coil neutralizes the harmonics in a manner best explained by first considering the device as a conventional transformer with the neutralizing coil disconnected. Though this coil is now open circuited, it has a voltage induced in it as a portion of the magnetic flux passes through the center leg of the core to the outer legs. Since some of the primary flux links this coil, fundamental voltage is present. The resultant voltage has high odd-harmonics content due to the leakage flux from the output winding. This leakage flux can return to the output winding by two paths. One bypasses the neutralizing coil. The other path links the neutralizing coil completely, by controlling the reluctances of these magnetic paths, one can control the degree of the secondary flux coupled to the neutralizing coil.

The neutralizing coil is connected with its polarity additive to the secondary (or output coil), that output of the newly formed regulator has constant voltage with a waveshape almost completely free of harmonics.

The harmonics are still present in the output windings and also in the neutralizing coil. Since those harmonics present in the neutralizing coil are induced by the flux from the secondary winding, the harmonics in each coil are approximately 180* out of the phase. This results in their cancellation. Proper control of turns ratio and magnetic path reluctance contribute to the generation of sinusoidal output – even with square wave input."

 

[mohpower]

hello guys,

please give your feedback on my previous message

thanks

http://www.ierltd.com

 

[mohpower]

hello guys,

please give your feedback on my previous message

thanks

http://www.ierltd.com

 

[buzz41]

Thx mohpower for the post. If I read that post just one more time, I think I'll have it down for good. That "ferro-resonance" has been a bit of a mystery 'til now.

I might add that I had used these regulators many years ago. There is one MAJOR shortcoming of these units that anyone contemplating using them should keep in mind: They are very frequency sensitive. A 1 percent freq deviation can cause a much larger voltage change, maybe 3 or 5 percent. (guessing from memory)

So, using them from anything other than the "grid" may make things worse instead of better. (experience) But, applied within its limitations, a Sola unit should be very reliable.

Incidentally, most microwave ovens use this same type of regulation and therefore will also be very power freq sensitive.

ron

 

[itsmoked]

mohpower; I believe the description given to you by SOLA is spot on accurate. There is no question their power conditioners work and work well.

I don't recall ever seeing anything but a sine-wave on the 40 or so that have gone thru my clutches.. We shipped them with a product we sold for many years.

I will say that if you look at all their data sheets you will see over and over, even twice in the same data sheet:

[green]"Output Harmonic Distortion 3% total RMS content at full load"[/green]

Which sounds pretty good to me... BUT! You could read between the lines that this is only at full load. At less than full load perhaps you could expect something else...

I can also see that they declare:
[green]"Efficiency up to 92% at full load."[/green]

Boy if that isn't a hedged bet.. "up to" always a giant flag. Plus dependant on a specific condition.

I would still question using one since they really are inefficient at lower ratings. I did mean fry eggs. They will burn the hell out of you. That exposed transformer core probably hits about 200F in normal operation.

I would probably seek another method unless I was running a specific application that essentially ran the Sola at full power all the time.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[mohpower]

I really appreciate your comments.
thank you very much

http://www.ierltd.com

 

[rawelk]

For completeness, I'll add that Sola MCR transformers have a minimum loading rating (if memory serves, 50 or 60% of full load). I learned this when a fairly large MCR suffered capacitor failure after only a few years of service.

In the past when I've used them, it was my habit to closely calculate the loads - these suckers are expensive - and only pad it by 20%. I guess the OEM that integrated the failed MCR into our equipment was working on the "bigger is better" premise - when I looked at line current it was only 40% of FLA. Replaced the transformer with a smaller one, and haven't had problems since.