Experience Using PWM Autotransformer for Sag Mitigation

Possibly, but a better alternative would be to use a UPS system that is always producing/conditioning the line voltage from an adequately sized battery bank that is always being charged by the grid. An autotransformer has very limited energy storage and may not react fast enough to carry you through long severe dips.

A lightning strike never cause voltage sags by itself. The lightning episode last only microseconds, while the period of the power frequency is 20 milliseconds Sags are causes by the malfunction of equipment due to current or voltage of a lightning strike.

Have never heard of a »PWM autotransformer«, but sufficient to say, if your equipment is very sensitive to sags and surges, you will have to consider a UPS installation that is totally isolated from the power grid. Such a UPS system will operate from DC that is replentished from the power grid.

No mater how strong could be the network it can usually produce voltage sag by switching-off large load, energizing apacitor load, network system fault or lightning strike impact over the overhead distribution line in which case arc extinguishing period is estimated in about 500 ms.

In this scenary, the voltage dip is not in the order of microseconds but could be about 500 ms, therefore affecting sensitive machines. That is why I ask for experience of the PWM autotransformer instead the expensive DVR or Statcom. please reference in: Displines Cover review Guideline Format Research Paer FAQ or World Academic Union

Agree with #1↑ and #2↑. Go for an UPS instead.

Voltage sag indicates a supply problem: the local distribution network is undersized. Get on to the local utility supplier, and make a commercially-based complaint, at Managing Director level if need be.

NO, I DO NOT BUY IT.

Oh, The OP might think so, but no. Electrical sags run in the milliseconds to a fraction of seconds, if power returns at all. Beyond a cycle or so no gimmick helps.

On the other hand, the thermal time constant of an iniector body ought to be in the seconds.

You want to keep its temperature constant or near so? Explore oils, phase change waxes, and soldering metals kept at high enough temperatures, ,and circulated when needed, at whatever temp. needed.

When you calculate the energy equations, this will be far the most advantageous.

Ok Sir., I appreciete to much your wise consideration but in this case it is not the kinetic Thermal canstant related to the voltage sag is the problem because it can't develop in 500 ms and for longer time than this, the EDG will start to resuitching power back.

Please revise my explanation dated on 31/01/2013 where is described in short detail the negative effect on the power quality dispite existing strong power system supply. The plastic making machine due to its several interative components and devices require a synchronized operation or else film breakdonw therefore 500 ms voltage last lead the machines out of production. Pleas if any of the Forum member know about the application of the referred PWM autotransformer or manufacturer, please notify me by this way

It appears that there are a number of academic papers on this topic, here's one:

https://smartech.gatech.edu/bitstream/handle/1853/5215/lee_dongmyung_200405_phd.pdf

Just Google on your title, there's enough information to build your own, but it seems that no-one is offering a unit for sale. When you read the papers you will see why they are still in the lab; first they have to recognize a fault, then they have to react to it, and all that takes time, but most importantly each authors' design achieves its goal by reducing the cost by engineering out any appreciable energy storage! So unless your goal is to support a low power controller, such a design will not carry your entire machine through an appreciable sag.

As stated previously, the proper UPS running off of separately charged batteries has no time lag and does have high load carrying capability, plus they're readily available.

No doubt, you are right, PWM autotransformer is still on reseach stage from several Labs and not manufacturer decide to put in their line of production as yet, all academic paper show them as the best Sag and swell solution. Thanks a lot for clarify me about it so I would try to solve it out by means of DVR or UPS as all of your advise me.

Thanks everyones