VEG Automatic Voltage Regulator - The Saga

[Crossy]

EDIT I've split this AVR Saga off from the other AVR thread, any issues with VEG AVRs please put here.

 

Well, our VEG 20000 has decided to stop regulating ????

 

With the juice off I cannot move the variac brush so something is jammed.

 

Time to bypass the beast and investigate the gearbox ????

 

[Crossy]

10 minutes ago, Arjen said:

I hope you are succes full in repairing it!

Job for the weekend to bypass the beast and pull the motor and gearbox, we shall see what's amiss then.

 

EDIT I suppose I'm lucky in having the time, tools, knowledge and enthusiasm to fix this sort of thing. I will of course post photos of the issues found and my fixes.

 

[Crossy]

1 minute ago, Arjen said:

I know you told me yours was moveable, but that seems not with all the case.

Yup, ours definitely was moveable by hand, now it's not. Of course this could be a red herring. 

[Crossy]

Well it's fixed, hurrah ????

 

Unfortunately, I don't know exactly how I fixed it (these things worry me) ???? 

 

The story:-

• Sent Wifey off to her mums for the day.
• Bypassed the beastie and got it into the middle of the room.
• Verified again that I could NOT move the brush by hand.
• Took off the brush arm (3 locking screws to the motor shaft).
• Removed the motor (3 more screws and 2 wires (snipped).

Motor is a cheap Chinese 12V motor and gearbox, should be easy enough to get a new one in Ban Mo.

 

Checked the motor on a 12V battery, of course it did what one would expect (rotated fine). Ran it in both directions, no nasty noises or sticking. It's a sealed unit so I couldn't check the gears themselves, but it doesn't exactly have a hard life.

• So, I put it back together.
• Checked and I most definitely CAN now move the brush by hand.
• Hooked up temporary power to it I and did some tests (using our water heater to pull down the supply).
• Wired it all back up.
• Tested again with the water heater, it still does all the right things.

So I really don't know what was wrong, the carbon brush is in good condition and springs happily, not a lot else it could be.

 

I did notice that the little cooling fan on the brush arm is running a bit slow, so that needs replacing.

 

Other than that, I'll just keep an eye on it.

 

 

[bankruatsteve]

Do you think removing the brush arm might have released some kind of stiction?  Also, did you notice the pot or whatever controls the thing?  (I still haven't gotten around to taking the cover off of mine.)

[Crossy]

2 hours ago, bankruatsteve said:

Do you think removing the brush arm might have released some kind of stiction?

Almost certainly, it's just not obvious where it was. Nothing visible on the bearing face of the variac.

 

We shall just have to watch the beast and see how it behaves.

 

It is nice to know that a stalled variac motor doesn't kill the driver electronics ????

 

[Crossy]

A quick bump of this thread as the AVR had a bit of a wobbler last week.

 

Family visit so all the A/C was running (I found out later that the UK-ites had it set to 16C in the bedrooms - power bill was 8,200 Baht) middle of the night the genset started, rest of the village still on. Quick investigation showed the incoming mains fine but the AVR with no output.

 

I was just just about to decide how to bypass the beast in the middle of the night when - tada - it turned on. It did feel somewhat warm (suspected overheat) so I opened the front door, aimed a fan inside and went back to bed. It didn't go off again and was happy for the rest of the family visit (still with the door open and the fan pointing inside).

 

Now the family have left time to investigate.

 

There's a little baby fan on the variac brush (along with a thermal switch which is probably what killed the output), it was not rotating (seized solid). There was a replacement 12V fan in my "keep it for a rainy day" box, 30 mins later that's installed and going round.

 

Looking into the bowels of the beast revealed that the main ventilation fan also wasn't going round (220V 4" fan), this one wasn't seized, but was open circuit (burned out). A replacement was again rustled up from my magic box. Worked fine but was a LOT more noisy than the original (it lives in the corner of the lounge and was disturbing my enjoyment of the IPL). Bunged a 1uF 250V AC motor run capacitor in series which dropped the fan voltage down to about 120V, it's still moving air but is much quieter.

 

So we are back online, I'm a bit miffed that the fans failed after less then 2 years (cheap Chinese) but the replacements are better quality so with luck that's something else to not go wrong.

 

Next job is to add a thermostat to the main fan so it only runs when the box is getting warm, one of these is on order https://www.aliexpress.com/item/W3001-W3002-W3230-LED-Digital-Thermostat-Temperature-Controller-AC-110V-220V-DC12V-24V-Thermoregulator-Heating-Cooling/33004698151.html the W3001 220V version.

 

So the fan can run at full speed only when needed.

 

 

 

 

 

 

[Crossy]

8 minutes ago, Arjen said:

I know making the fan temp. controlled is not a big job, (I did this with the fans from the power supply from my CCTV). What I like from the CBC AVR, is that the fans (It has no door what is easy to open as the VEG) there are more, but I have no idea how many, are even speed controlled. At night I hear them hardly never running (supply voltage is also usual OK when it is cooler) at day time they only run when the load is high together with a low supply voltage.

 

Yeah, if I knew then what I know now I would have bought the CBC (at the time Global only had Lioa and VEG).

 

On the other hand the VEG is really easy to access for maintenance. If I could find some drawings for the beast I would be a happy bunny.

[Crossy]

Since the beast has demonstrated a propensity for going belly up in the middle of the night I have installed a bypass switch.

 

I had one of these in stock, it's actually intended as a generator transfer switch, but with a little lateral thinking it's become an AVR isolator and bypass.

 

https://www.aliexpress.com/item/2P-63A-MTS-Dual-power-Manual-transfer-switch-Circuit-breaker-MCB-50HZ-60HZ-400/32786129292.html

 

Drawings coming shortly.

 

[Crossy]

As promised, quick-and-dirty drawing

 

 

All wires should be at least 10mm², the neutral just goes past without connecting to the switches.

 

With the switches as shown the AVR is bypassed and isolated, check dead before touching anything.

 

Whilst the two breakers are interlocked so they cannot both be on together it is strongly advised to set them both to off whilst switching from normal (left breaker on) to bypass (right breaker on).

 

[bankruatsteve]

Crossy, when you conduct testing on the VEG, how big a load do you use?  Or, after beating on it do you just punch it back in-line?

[Crossy]

20 hours ago, bankruatsteve said:

Crossy, when you conduct testing on the VEG, how big a load do you use?  Or, after beating on it do you just punch it back in-line?

 

A bit of both.

 

I have a 3kW "test load" (OK it's a UK kettle, bonus is I can have a cuppa whilst testing) which is enough to verify it's functioning and I can "adjust" the input voltage by turning on up to 14kW (60A or so) of water heaters (I don't own a variac).

 

The water heaters are on the supply side of the AVR, our load source impedance measures at about 0.5 ohms so 60A will give me a voltage drop of about 30V from whatever PEA are deigning to supply at the time (currently a nice 211V @ 15A load).

 

Otherwise bang it back in line and turn on the aircon.

 

[sometimewoodworker]

7 hours ago, Crossy said:

The water heaters are on the supply side of the AVR, our load source impedance measures at about 0.5 ohms so 60A will give me a voltage drop of about 30V from whatever PEA are deigning to supply at the time (currently a nice 211V @ 15A load).

I'm a little unsure of what you are saying there. Do you mean that when you put a 60A load your incoming voltage will drop from 211V down to 181V?

If I'm correct would this be normal? 

 

I think that for each 20A increase in load my incoming voltage will drop by about 10V and I'm trying to discover if that is expected or if a trip to the PEA may help.

[Crossy]

3 minutes ago, sometimewoodworker said:

I'm a little unsure of what you are saying there. Do you mean that when you put a 60A load your incoming voltage will drop from 211V down to 181V?

If I'm correct would this be normal? 

 

I think that for each 20A increase in load my incoming voltage will drop by about 10V and I'm trying to discover if that is expected or if a trip to the PEA may help.

 

Yes, that's what I'm saying, your 20A load dropping 10V suggests a similar supply impedance.

 

It's not good, but I doubt it's particularly abnormal for a village setting, relatively small transformer near it's maximum rating, distribution cabling on the small side.

 

Our main issue is that sometimes the voltage starts off at 200V and heads downwards from there.

 

Standard PEA response "you have electric, no problem".

 

[Fruit Trader]

In Delhi the hundreds of AVR's fight and dance in an effort to gain dominance.

[Crossy]

1 hour ago, Fruit Trader said:

In Delhi the hundreds of AVR's fight and dance in an effort to gain dominance.

 

Indeed, along with dozens of baby gensets clattering away in the night.

 

Our place in Vasant Vihar had a 3-phase supply feeding three outlets next to the TV. Plug the TV into the phase working best at the time.

[bluesofa]

3 hours ago, Crossy said:

 

Yes, that's what I'm saying, your 20A load dropping 10V suggests a similar supply impedance.

 

It's not good, but I doubt it's particularly abnormal for a village setting, relatively small transformer near it's maximum rating, distribution cabling on the small side.

 

Our main issue is that sometimes the voltage starts off at 200V and heads downwards from there.

 

Standard PEA response "you have electric, no problem".

Is that a serious quote from the PEA, or just a reply you'd expect from experience dealing with them?

 

[Crossy]

5 minutes ago, bluesofa said:

Is that a serious quote from the PEA, or just a reply you'd expect from experience dealing with them?

 

Tongue in cheek, but it's exactly what I would be expecting from them from personal experience and numerous posts on TV.

[sometimewoodworker]

44 minutes ago, Crossy said:

 

50 minutes ago, bluesofa said:

Is that a serious quote from the PEA, or just a reply you'd expect from experience dealing with them?

 

Tongue in cheek, but it's exactly what I would be expecting from them from personal experience and numerous posts on TV.

 

I hope will be talking to the head of the local PEA within a couple of months, maybe sooner but it depends on how kind SWMBO is feeling, we do have a little bit of a better chance as they went to school together so he will probably at least listen. We will be going along armed with a bottle of reasonabl whiskey anyway. Once I've had the meeting I'll report on what the response was.

[Crossy]

So, the temperature controller has arrived, after checking it worked it was dismantled and the box sprayed black. I mounted it on the ouside coz I like to see what's going on.

 

 

 

The sensor is on the variac arm in the airflow from the small fan. Experimental location, if anyone has a better Idea I'm all ears ????

 

 

 

So what temperatures to set? Currently it's set to start the fan at 40^oC and stop it at 39.5^oC. Ambient is currently 38^oC so with luck it will actually get to start and stop.

 

Currently it's running at about 39.6^oC with the input at 218V and 11A. We shall see what it does later when the aircon is on and the input voltage is lower as it usually is in the evening.

 

The rear fan is still on slow (1uF series capacitor) we shall see how things perform, it sounds like a 747 with no capacitor.

 

I'm still waiting for the new, all ballrace, small fan. The one currently installed is a cheap, sleeve-bearing job that was in the bits box.

 

[Crossy]

Having watched the beast intently (ok looked at it sometimes) I have:-

• Set the cooling "on" temperature to 40^oC
• Set the cooling "off" temperature to 37^oC
• Removed the capacitor so the rear fan runs at full speed

I've also put an external baffle on the rear fan so it doesn't annoy Madam by making a dust mark on the wall.

 

It spends most of its time with the rear fan off and around 38^oC internal temperature.

 

[Crossy]

After spending the evening listening to a 747 crank up every 10 minutes or so I've finally wired the fan as I should have from the start.

 

Constant running at the (quiet) low speed with the temperature controller giving at a boost when the beast is working really hard.

 

[farmerjo]

On 1/4/2019 at 9:34 AM, Arjen said:

I hope you are succes full in repairing it!

 

According to my local Global House they have a lot of bad experiences with VEG, and they are absolute not happy with the support from VEG when something goes wrong (what seems to be often) 

 

The staff has received the order to not sale them anymore. They are still on display, as it is a company rule.

 

In case you buy a new one, I am very happy with my new one:

CBC ZTY-20KVA/1. I was also happy with my VEG when it worked, but even when compare both when they are new, the CBC has some advantages. It responses faster (much faster), although it is sometimes a bit slow with regulating the voltage back when after a low voltage the voltage is going up again. The biggest advantage from the CBC compared to the VEG is that it is much more quiet. The fans only run when neccessary, while from the VEG they are runing when you power it on, even without a load. For that reason I placed the CBC downstairs, not knowing it is much more quiet. (First the AVR was placed close to my bed.....) 

 

Big disadvantage can be that it is more expansive, I paid 24.500 Baht.

 

Arjen.

Will bump this thread,Arjen did you get CBC to come and install your AVR or just purchase it from them.

[bankruatsteve]

I think the above units are 20kVA.  I have a VEG 10k for several years; not noisy and, so far, reliable.  It does 'bang' in to a start position.  FYI

[notrub]

I see many CBC AVR units listed on Lazada.  from about 2,000 to 15,000 (Uninterruptible Power Supplies 3 Kva - 2400W Brand CBC Model EA-630 EA 600 Pure Series Sine Wave UPS -is 15K).  I can think of how to reroute the feed for the fridge, microwave and pool pump to one location.  How do I calculate what I need as an output to feed these devices?  Please.  Is it that my pool pump will function on low voltage (it does) but is it that 160 volts will shorted its lifespan?  Will my refrigerator be damaged by having only a 160 volt supply?

 

Also, will low voltage cause my RCBO unit to not function properly?

 

Thanks very much in advance for any help and also thanks for posting about AVR in the first place.  I knew that voltage could be lowered but was not aware that it could be raised.   

[Crossy]

1 hour ago, notrub said:

I see many CBC AVR units listed on Lazada.  from about 2,000 to 15,000 (Uninterruptible Power Supplies 3 Kva - 2400W Brand CBC Model EA-630 EA 600 Pure Series Sine Wave UPS -is 15K).

 

An AVR and a UPS are not the same thing. You need an AVR if you have voltage fluctuations.

 

Induction motors (anything not "inverter") will get hotter than intended if the supply voltage is chronically low, this will in-turn shorten its life.

 

Have a look at the pinned thread on selecting and installing an AVR.

[ankit singh]

The automatic voltage regulator is used to regulate the voltage. The automatic voltage regulator is used to increase the excitation of the system under fault conditions. Also is mostly used in welding industries. 
AVR and UPS both are two different things. 

[farmerjo]

Ok,have bitten the bullet and bought a TTY 20kva/1 CBC AVR.(34,000 baht)

Thinks it's the later version of the STY series the engineer i talked to told me.

Will build a doghouse for it outside,weatherproof but with ventilation.

He is providing lugs to suit copper cable and i will have to splice to the 25mm aluminium.

According to the specs it all seems there protection wise and has a bypass.

What else do i need for it when the sparky comes to wire up,will be 25 al into copper on input and same on output and a groundrod.

Do i need a safety cut in between it and meter? or any other devices,thanks.

 

.http://www.cbcinter.co.th/wp-content/uploads/2019/07/STY-20KVA_EN.pdf

 

[Crossy]

I would put some sort of isolator between the AVR and the meter so you can safely work on the AVR. Even one of the Chang knife switches would do the trick, cheap and effective.

 

When you build your shed make sure the floor is well above any potential flooding and then some (obvious I know but ...)

 

If you already have earth leakage protection elsewhere then I wouldn't bother with anything extra.

[farmerjo]

1 hour ago, Crossy said:

I would put some sort of isolator between the AVR and the meter so you can safely work on the AVR. Even one of the Chang knife switches would do the trick, cheap and effective.

 

When you build your shed make sure the floor is well above any potential flooding and then some (obvious I know but ...)

 

If you already have earth leakage protection elsewhere then I wouldn't bother with anything extra.

Thanks Crossy????