Voltage Regulator and Buzzing Sounds!

[Smart_Guy]

Hey guys, been a while since I started a technical thread

Ehm...

I'm using a voltage regulator that makes a buzzing sound every once in a while. I notice it mostly if the A/C is running and it disconnects/connects the compressor.

Lately it gives very long buzzes, and once the buzzing became so high and the device disconnected. I turned it off for some time then on and it worked again fine.

Any idea?

 

[particleman]

Have you checked the voltage from the regulator? What kind of regulator is it (brand/model)?

 

[Smart_Guy]

It's some Japanese brand called Auto Stac. Yes, the voltage is fixed a little before 220V.

Now it's giving a non stop buzzing.

I think it's busted!

Still works fine tho if we (can afford to) ignore the sound!

 

[cb600fshornet]

Dunno, sounds broke.

 

[Smart_Guy]

Hmm...

Thanks for your replies guys

 

[connchri]

Any model name and number? Electrical Engineer here...

I'm not sure exactly what you are talking about when you say just a regulator, but I'll assume its something with a heafty transformer, or other coils, in it.

In which case, the motor for the compressor is probably an induction motor, and consumes a bit of reactive power. If your regulator does power factor correction, and/or you have additional load on the thing, then you might get a lot more noises.

A disconnection could be the protection kicking in. A small transformer, such as though found in domestic or small office UPSs will buzz a bit when under load - and the compressor, in this case, would be ample load for this to occur. If this is what is happening, then I wouldn't consider it an issue. If it's doing it constantly, then perhaps some windings aren't holding or some inductors are getting noisy too - not indicitive of a failure itself, but it could be coming soon.

I doubt very much that it will fail catastrophically, I've just look at the brands website and they look pro enough, so I'd trust that it has the protection required to stop any "bangs".

Still, I don't know exactly what your talking about, so if you can give me a model number, and perhaps that of the aircon unit as well, that'd be great.

 

[Celery]

Is the output DC? If so, I'd look at the caps.

 

[Smart_Guy]

Thanks again guys

The model number is ST1000W-SASO
portable series of STAC

Even without the A/C running (it is not connected to the regulator actually) it does buzz from time to time.

I forgot to say something. When the device disconnected (turned off completely) it shorted. I even saw an electrical bolt as if something blew up. It didn't work again until I turned the switch off for sometime then on again.

Now it always give continues high buzzing enough to wake me up at night. Still working tho giving stable voltage of 220v.

I'm thinking of taking it back to the shop. Maybe they will replace it or something. It worked for like a week with just simple buzzes when the electricity acts up. Yeah, it's new.

 

[connchri]

Even without the A/C running (it is not connected to the regulator actually) it does buzz from time to time.

That's just part and parcel of using a trasformer, you'll get a hum, or buzz, due to the 50Hz/60Hz supply. Due to the magenetic forces in the coils, they'll vibrate somewhat.

I forgot to say something. When the device disconnected (turned off completely) it shorted. I even saw an electrical bolt as if something blew up. It didn't work again until I turned the switch off for sometime then on again.

Sounds as though the protection kicked in. The flash you seen could have been arching from some relay/contactor/breaker disconnecting. Latching until it's cleared the fault can be normal too - depending on what protection it has.

Now it always give continues high buzzing enough to wake me up at night. Still working tho giving stable voltage of 220v.

If it was overloaded, then the magnetic forces acting on the coils, and hence the forces on the core and everything holding it together, may have slightly caused it to deform/losen at some location. I don't mean in a huge way, just in a small enough way that the vibrations are more noticable.

Are there any smells? Bad smells could be a sign damage. If none, then, if it was me, I wouldn't worry about it.

One thing you didn't say is the type of Air Con unit you have. These are rarely low wattage/VA items.

Your converter is rated for 1000VA - note, this is different from power (W - watts). As the compressor consumes VAs, and there appears to be no power factor correction on that unit, then it could be simply the case that the compressor is over loading it. You could fire in an ammeter to find the load on the compressor - if it's more than just over 4 Amps, then there's your problem. Plus, if it's got an induction motor, then the inrush current could be far higher - say 16 to 25 amps.

You should have a ratings plate on your air-con unit. If your Air-Con unit has the power consumption only in Watts, then look for a power factor rating too (probably written as p.f). Multiply the Watts and the p.f. to get the VA of the unit. If it has a VA rating stated, then you have it. If that VA rating is above 1000, then you shouldn't be using it on this regulator. This is ignoring the possible issue with inrush current and the additional load of anything else connected. If your AC unit is rated at 800Watts, but has a p.f. of 1.3, then that gives you 1080VA and you're overloading it.

Hope we're getting there...

 

[connchri]

I made a boob, reading through that post. Anything I mentioned about power factor I was talking about its inverse (1/powerfactor) - I use that number more often.

Hence, if you have a power factor rating for it, and the wattage, divide the wattage by the power factor (power factor should always be less than one in reactive loads, and equal to one in purely resistive loads).