AVR/AVS question

[bankruatsteve]

So, I'm going to buy an AVR/AVS (whatever) tomorrow and just wondering a few things:

 

1)  I'm thinking a 7.5 KVA because my demand is never above that.  Or, is this like a genset where one would need to go higher than "demand".

2)  When the voltage is lower/higher than the specs, what does the thing do?  Does it trip like a breaker and then have to reset or ??

3)  I should just connect to the main and not try to also regulate my genset on the DPDT switch, right?

[carlyai]

I'll let the man with knowledge answer this, I'll just make a couple of comments.

I have 3 of them for my 3 phases.

I see there are a few options around now, but I would say make sure you get one with a servo motor, that automatically adjusts.

I think you need to also look at their specs. (like graphs) closer than I did, as I've had great service from them, but a couple of funny things happen.

As I've got lights and fans etc on different phases I did notice, only one time, that some of the fans were running slowly, but the AVR concerned voltage was way down and couldn't regulate, but kept going. Only happened once.

The other strange thing was, pre-Song Kran we had one of those extra loud music shows, where the base rattles your liver 15 km away. I went into the bedroom and the LED lights were dimming to the same tune as the base notes. So it was on one phase, but the AVR was quite happy chugging along. Maybe something to do with it's response time, or something.

So it's worth studying the specs and getting a probably more expensive model.

I have had one fault on one AVR where the meter voltage reads high, but the output voltage is OK.

Trying to get a response from the makers or distributors is the same as getting responses from LG or ACER. Hopeless.

 

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[Crossy]

1. Get a bigger one than you think you need, 10kVA.
2. When it runs out of regulation (invariably on under voltage) it will continue to prop up the voltage at its maximum boost until the current rating on the input is exceeded and the breaker opens. If this happens regularly your AVR is too small.
3. Just regulate the mains, your genset should do a reasonable job of regulating itself.

[carlyai]

This is my temp/perm set up.
I tried to capture the meter response to someone welding down the road but couldn't.
SWMBO thought she'd brighten up the area with a flowered bike to hide the AVRs.
As hard as I try to keep only the AVRs in the space, various things get placed there. At least the flower pots with water aren't there any more.
You should try and install your AVR somewhere the wife can't decorate or paint purple, orange, green and yellow.
Saw a pic. of a swimming pool last week with red tiles.

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[Crossy]

AVRs appear (like so many other things) to be specified somewhat "optimistically". i.e. They only meet their specified rating over a very small range of input voltages (basically at 220V).

 

Here's what I suggest you do to size the beast.

1. Determine your maximum load (7.5kVA)
2. Work out the current that would need to be drawn at the minimum supply voltage (let's say 160V) to provide that load. (7500/160 = 46.8A)
3. Multiply that current by the nominal supply (220V) to get a kVA value (220*46.8=10,296 = 10kVA)
4. Buy the nearest rated AVR, go bigger rather than smaller unless you're only just over a size.

 

[carlyai]

Don't know if you have a outdoor amplifier place called Bangkok Outlet near you, but they have all sorts of gensets and AVRs for those outdoor, wheel mounted, sound systems. Some really neat looking AVRs.

Think the same brand as Naam bought.

 

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[bankruatsteve]

46 minutes ago, Crossy said:

AVRs appear (like so many other things) to be specified somewhat "optimistically". i.e. They only meet their specified rating over a very small range of input voltages (basically at 220V).

 

Here's what I suggest you do to size the beast.

1. Determine your maximum load (7.5kVA)
2. Work out the current that would need to be drawn at the minimum supply voltage (let's say 160V) to provide that load. (7500/160 = 46.8A)
3. Multiply that current by the nominal supply (220V) to get a kVA value (220*46.8=10,296 = 10kVA)
4. Buy the nearest rated AVR, go bigger rather than smaller unless you're only just over a size.

 

 

If it makes a difference...  my "problem" is not under-voltage but over-voltage.  It typically ranges between 238-244 but has times where it bumps higher (that's when the fans seem like on steroids).  I worry that stuff not designed to handle over 240 V sustained will eventually have problems.  (Like my previous fridge.  Now have inverter type.)  When I do notice the voltage over 245, I power up the genset until it backs down a bit.  

 

[Crossy]

Generally, on over voltage the AVR will behave the same as on under. Once it reaches the maximum ratio it will continue to step down at that ratio.

 

Do check the spec. of the AVR as to how high it will go, they do tend to concentrate on the boost side of the equation.

 

Can you send us some of your spare volts please

[bankruatsteve]

It's been a few days since I went to Global (this in Udon Thani) with intention of buying an AVS there but, when I looked at the larger than I anticipated box, I couldn't work out how I would mount it to the wall.  (Didn't see any obvious mounts but maybe I missed something?)  Without time to look for platform to hold it, I decided to check out the other "Homes".

 

Well... Home Pro doesn't carry them and the staff at the electric and power stuff dept. had no idea what I was talking about.  Went to Do Home and could only find a "Transformer Step Up/Down".  That had a switch that could select one of 8 (I think) positions although I didn't study it.  The word "automatic" was nowhere to be found.  Actually, it looks like something salvaged from a WWII storage bin.  Went on to Home Hub and they had the same thing.  Aagh.

 

So, if anybody knows...

 

1)  Is the Global AVS easy to wall mount or will I need to buy/make a platform?

 

2)  Is the switch selector transformer more than meets the eye or is it as manual as it appears?

 

3)  Where have you all that have an AVR/AVS bought it?

 

Cheers

[carlyai]

Ask Naam...think he bought a good one.



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[Crossy]

Anything with a transformer is going to be heavy.

 

Weights are here http://www.lioa.com.vn/en/san-pham/ap-ap-1-pha/automatic-voltage-stabilizer-1-phase

 

[bankruatsteve]

OK.  

1 hour ago, Crossy said:

Anything with a transformer is going to be heavy.

 

Weights are here http://www.lioa.com.vn/en/san-pham/ap-ap-1-pha/automatic-voltage-stabilizer-1-phase

 

Now I understand that.  Is this a site you would suggest purchase?  I didn't see prices.  Otherwise, my questions remain.  :)

 

[Crossy]

The Lioa AVR is one of the brands commonly sold in Thailand (in Global House for example). I don't think you can buy directly from the Vietnam manufacturer (I may be wrong of course).

 

I don't think it is intended to be wall mounted, but if your walls can handle the weight you should be able to get brackets made up locally (like those used for aircon compressors).

 

The manual switchy thing is just that, manual, handy if your supply is constantly low or high, not so useful if it varies a lot. It may be the solution for your constantly high voltage.

 

Global House seems to carry the beasts (not in all branches), but if you're in an area where they are needed the specialist electrical places should be able to help as well.

 

[bankruatsteve]

To give this an ending...

 

I finally bought and installed the Vietnam made AVS from Global.  It's rated at 7500 VA which far exceeds anything we would even abnormally use.  Cost 7400 baht.  I gave up trying to find some way to wall mount as it just seems too heavy to do that.  I put it on a table so out of reach of any curious toddlers but not exactly living room decor.  I may try to get our welder guy to build something so it can be just beneath the genset transfer switch and then put a curtain around the whole works.

 

After hooking everything up, I turned on the isolator switch and power came on as normal except voltage now 223 V (versus mains at 238 V) so that's what I was hoping for.  The ammeter doesn't seem to be working though - but I won't bother about that.  The very limited instructions were in Vietnamese and I didn't see any warranty card - just FYI.

 

Cheers.

[carlyai]

I sent you a message

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[bankruatsteve]

Update... it turns out the AVS ammeter does work - sort of.  My daytime consumption is typically about 4 amps.  That did not register on the ammeter.  Last night I used my oven which draws about 10 amps and noticed the ammeter registering 11 amps.  So, just guessing that it was never calibrated and with error of 5-10 degrees low.  Whatever - I have an accurate ammeter so not a big deal.

 

Another question if anybody knows:  There is a "Voltage Adjustment" screw inset in a small hole on the panel so obviously not something to play with.  But wondering when I would want or need to adjust the voltage?

[carlyai]

Update... it turns out the AVS ammeter does work - sort of.  My daytime consumption is typically about 4 amps.  That did not register on the ammeter.  Last night I used my oven which draws about 10 amps and noticed the ammeter registering 11 amps.  So, just guessing that it was never calibrated and with error of 5-10 degrees low.  Whatever - I have an accurate ammeter so not a big deal.
 
Another question if anybody knows:  There is a "Voltage Adjustment" screw inset in a small hole on the panel so obviously not something to play with.  But wondering when I would want or need to adjust the voltage?

Yes, it is surprising how little Amps you use, when you have a meter to look at. I was going to suggest this before but forgot.

With the stabaliser turned off, the meter pointers should point to zero. Previously, the little hole for screwdriver adjust used to be to adjust the meter pointer to zero.
This doesn't seem to be the case with the Lion stabaliser.

If you turn that little potentiometer adjuster, you can hear the servo control move, so I think it is to set the output to 220v. If you use your other meter and rotate the screwdriver in the hole, you will see the voltage change. Just make sure it is at 220 V.

My genset didn't have an output current or Amp meter. When I test run it I wanted to load it 90%, so I installed a small current/voltage meter on the changeover switch, then when I switched to gen set I could see what my load was.

It was surprising, cause I calculated about 22 A, but my Chinese set started to complain at 14 A load, and it would never deliver 22 A.

It could be the way I have it set up. Using a single phase genset to supply 3 separate phases.

I could try and find a photo of the amp volt meter if you're interested, but it's one Crossy used before.





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[carlyai]

Just running my sorta monthly genset and took a pic of the meter I have to check the load current etc.

Just thought I'd include this for you.


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[bankruatsteve]

Just wanted to update with something I found interesting about my AVS...

 

Brief background:  I now have two AVS, 7 KVA for the low demand upstairs and 10 KVA for down (load is typically between 5-8 amps but gets close to 30a when a bunch of stuff is on).  In doing this, I needed to change the output of my genset xfer switch from direct to the CU to where it goes through the AVS's.  (Just to explain that previously, when on genset power the AVS was not in circuit but now they are.)  Anyway....

 

Last night we had a voltage drop to 90v starting at 9pm and lasted until 5am.  The 10KVA tripped immediately and when I went out to fire up the gen I noticed that the left side garden lights were still on.  It turns out the 7.5KVA was happily cranking up the 90v to 222v (the little over 1amp load probably allowed that to happen).  The AVS is rated for 180v to 240v so that's what I thought was interesting.  The other interest was finding that the AVS took the gen output of 217v to 222v and made for much smoother running when the load changed (like the 4.5a water pump).  My gen is only 2KVA and used to start barking when the pump comes on but now (with the AVS) makes an almost unnoticeable transition.  

 

OK, maybe not that interesting but now that I typed all this I'll post it.  Cheers.

[bankruatsteve]

1 minute ago, Arjen said:

I suppose AVS is same as AVR.

Ya.  I use AVS (stabilizer) because that's what it has on the box.

 

Yeah, although a bit pricey, these things really help the voltage issues.  While the situation is better now, my problem was high voltage - at times maintaining 245-250v for hours.  My fans acted like they were on steroids, my inverter fridge would bark and beep, and my TV and receiver would shut down.  And then I would have to run the gen until the voltage settled down to the 230's but such a pain in the ass.  Electrics that are copacetic also lessen my hypertension issues.  Cheers.