Power Line Conditioner

[jacquesl]

Hi,

Does anyone know how to build a Power Line Conditioner?

Its used to compensate peaks and valleys in the power supply and reduce peaks in the power flow to what is needed by the machine. For instance, on a 120 volt service, if the voltage exceeds 130 volts, the output is switched to a transformer that reduces the voltage by about 8% to keep it closer to 120 volts. The same is true if the voltage drops below 110 volts, the output switches to a different transformer that increases voltage by about 9%. However, if the voltage drops below 90 volts, or exceeds 140 volts, the power is shut off and then after this the Inverter will probably kicks in, running from 12V DC source

But I’m in South Africa so I’ll make it 250V max //Standard

[Pano]

In North America Furman sell a range of power conditioners that do exactly this. I've used them plenty in pro audio and video.

They use a special multitap autotransfomer (toroidal). Triacs are used to switch to the winding needed to keep the voltage steady - up or down. You can see this happen in real time on an LED bar graph on the front panel. Each LED is driven from the same circuit that drives the triacs.

Beyond that, I can't tell you what they use as a voltage sensor, but there are a number of IC on the board. There must be a passage by zereo detector, too - so that the switching takes place at zero volts.

This kind of device is going to be hard to DIY, as it takes a special transformer.

[Eva]

A variac controlled by a servo may be another alternative. Sometimes there are variacs for sale in ebay for very cheap.

[wine&dine]

Originally posted by Eva
A variac controlled by a servo may be another alternative. Sometimes there are variacs for sale in ebay for very cheap.

I had suggested that one before in another thread - the servo mechanism woudn't be too hard for DIY.

Other "classical" methods are magnetic constanters using a transductor (aka mag-amp), or a motor/generator combination with a flywheel for energy storage - these were used in the old days of IT to filter computer center power (and before that for iron works ...)

[AndrewT]

Hi,
would a string of comparators each set up as window comparators measuring DC rectified from the variable AC give an acceptable output controller?

Each comparator output would pull in a different tapping on the primary side.

I see primary side tappings as the way to maintain ampere turns and thus VA at near constant value.

A little bit of hysteresis would prevent chattering of the relays.

The transformer could be an autoformer and the output treated as if direct on line from the safety perspective.

[martin clark]

That's pretty much exactly how the 'small' one I have at home works - 1.5KVA transformer with multiple taps on the primary, made by these people.

[AndrewT]

Hi,
nice to get the occasional confirmation that I'n not "off the planet".

[TechGuy]

An alternative method would be to rectify the power and generate a sine output from the rectified current. A PFC circuit could be used to regulate the DC voltage. A Sine wave output can be generated using a PWM controlled voltage regulator which would create half a sine wave followed by a full output bridge to flip the half wave output into a full sine wave. The response time would be a lot better than a varic controlled solution since a electronic controlled system can response in milliseconds or even microseconds.

To further reduce noise and distortion, a synthesized sine wave can be generated to reduce or eliminate harmonics. Google for "Magic sine waves" for more info.

Hope this was useful.

[jackinnj]

Originally posted by TechGuy


To further reduce noise and distortion, a synthesized sine wave can be generated to reduce or eliminate harmonics. Google for "Magic sine waves" for more info.

Hope this was useful.

Ya know, I talked to Don Lancaster about that...

Regeneration is at most 70% efficient, the rest goes up in heat.

[IVX]

jackinnj,
i've feeling, 70% efficiency it's rather shameful at moment, 2007 isn't it?
TechGuy,
A) IMO, flipping isn't good solution in the precision terms, i wouldn't be able to take the feedback after all. In the USA 120VAC, so just a 200V mosfets required, why the flipping is needed?
B) Pre-emphasis will work adequately only at the single type of loads, for what was adjusted one. BTW, such pre-emphasis nice way to improve precision of the cheap reference sine DAC, i had try it for ATmega8 11Bit PWM.