Automatic Voltage Stabilizers - AVS/AVR/UPS

[hin]

Been lots of discussion about Thailand’s electrical problems pn other threads in the past but the forum’s search feature cannot find them

Found nice ‘Zircon’ relay type toroidal transformer automatic voltage stabilizers today at Power Buy. - 1000VA model at ฿2850. Exact same model at Lazada is ฿2990 www.lazada.co.th/products/stabilizer-1 ... 3&search=1

I bought one and there were 3 more on the shelf - next to the UPSs in the computer section. They are available at 1000VA, 1200VA, 1500VA & 2000VA but the ones at Power Buy and on Lazada site are 1000. Global House also has some other brands in several sizes up to 22,000VA which would provide for most people’s whole house, minus the water heaters which do not need it. We have most of our important stuff protected individually.

Technical difference between AVR and AVS can generate endless discussion, argument, and dispute equivalent to a sharp toothed dog chasing his tail, so excellant opportunity for self appointed experts to chirp away. But one simplification of the difference complements of Mr Google is:

A voltage regulator is a circuit or device designed to deliver a constant voltage at its output regardless of changes in load current.

A voltage stabilizer is a circuit or device designed to deliver a constant voltage at its output regardless of changes in incoming voltage.

[hin]

Well, that link to the Lazada AVS seems to not work, so will just try to cut and paste it without doing a link

https://www.lazada.co.th/products/stabi ... 3&search=1

[Nereus]

Technical difference between AVR and AVS can generate endless discussion, argument, and dispute equivalent to a sharp toothed dog chasing his tail, so excellant opportunity for self appointed experts to chirp away. But one simplification of the difference complements of Mr Google is:

No real need to be sarcastic, or make such statements. If you have some technical knowledge to share go right ahead so everybody may benefit. You may not know it, but there are qualified people on here that DO know what the difference is without referring to Mr Google!

The items that you are quoting are little more than kids toys at that price. The capacity of 1,000VA or even 2,000VA MAY be enough to run a computer, but very little else. The cheapest type that I have seen that are of more use start at around 15,000 Baht and up. Global House have a couple of different brands, but be aware that the VEG units have had that many failures that they stopped stocking them. The CBC units appear to be better and last longer, but they can cost up around 25,000 Baht, for a 20KVA unit.

Also, these units are dealing with lethal voltages, and correct installation is required. Many years ago they were commonly called "Variacs" and mostly found in repair shops that needed a range of test voltages. They use a principle called "auto transformer" and MUST only be used where they are hard wired into an installation. Not so much of a problem just regulating an unstable voltage, but with cheap poor quality units a fault can cause the full line voltage to appear across the output.

The principle has now been adopted with addition of a voltage sensing circuit driving a small motor and gearbox to move the wiper arm on most of them. Some just use relays to change "tap" connections on the windings to change the voltage.

[hin]

Right, protecting the whole house can cost big bucks. A motive for buying this type of “toy” to individually protect some of our more coveted household toys or appliances. This one is 800 watts, enuf for what we are using it for and as mentioned is relay type with taped toroidal transformer plus protection circuitry. Which is a long step up from what most people have in their UPS to protect expensive computer equipment.

An auto transformer is simply a single winding transformer with appropriate taps and can be dangerous if there is an internal short or reversed polarity plus a ground short but is cheapest type to manufacture so household size multi winding transformers are almost non existent these days. A disconected autotransformer can be easily detected with an ohm meter on the taps.

Servo motor controlled variac transformers are nothing new, are old school. Very accurate and wide range voltage control but too slow if there are deep or sudden voltage swings. There are hundreds of them of varying quality and size on Alibaba and Ali Express. But solid state is it these days

There is no point in emulating big industry’s requirements just to protect a few toys in our houses. As said, - few people care to go that far for their expensive computer pr home entertainment equipment and many pass no thought at all to other household appliances..

But for anyone who is interested, as Lazada price requires additional ฿170 for freight, it makes Power Buy ฿310 cheaper, more than 10%. PB possibly does not know. But checking and supporting a local business worked out well on this one. Which was my 2nd point as I am grateful that we do still have a few places to shop locally but they are disappearing.

[HHTel]

But checking and supporting a local business worked out well on this one. Which was my 2nd point as I am grateful that we do still have a few places to shop locally but they are disappearing.

While I support your sentiment of supporting local businesses, Power Buy Company Ltd is part of the massive Central Group. It has around 100 branches with a turnover in excess of 25 billion.

Hardly a 'local business'.

[hin]

OK. So we should quit shopping at Macro, Tesco Lotus, Starbucks, Home-Pro and drop True, Dtac, AIS, etc etc..? But Bangkok it conglomerates are OK..? I am happy some of the big guys have made big investments in our city and are here. And if Big C ever shows up.I will patronize them too. Unfortunately the days of Mom & Pop stores on every corner are gone forever. But on the other hand this forum is very local and it is a shame that a small nucleus of one upmanship mentality is ruining it and has driven away too many worthwhile members. Sorry - off topic, but somtimes we need some logic

I am grateful that we do still have a few places to shop locally

[Dannie Boy]

In the UK even some of the large retailers (Debenhams, John Lewis etc) are closing stores due to lack of market penetration - if the likes of Amazon are killing even the big stores, what chance to the small outlets have?
Sorry

[laphanphon]

I'm a UPS fan, one for each appliance, if cost effective.

off topic...I buy from the vendor that offers the best value. Big fan of 'free market', and if you can't compete, should probably do something else.

[buksida]

The cheap (under 10k) ones are not really worth the materials they're made out of if you have serious electrical supply problems (as we do). I get through one of them every few months or so as the circuit board fries - our power goes out with a bang at least 4-5 times per week with exploding transformers and the PEA bods are too dumb to figure out it is the same problem every time so just apply another band aid and wait for the next explosion.

Would love to protect the whole house but its still cheaper to buy new electronics than invest in a monster UPS, keep replacing the cheap ones, or setup a large solar panel system.

Edit - Added 'UPS' to the thread title as most people will know them as that.

[Nereus]

Edit - Added 'UPS' to the thread title as most people will know them as that.

Sorry, no they are NOT the same and it is that misconception that leads to misunderstandings.

[buksida]

They are to most laypeople that do not have a PHD in electronics. Are these not what we are talking about? (note the search term used was not AVS or AVR as nothing comes up)

https://www.lazada.co.th/catalog/?q=ups ... 719ctkqCPu

[Nereus]

They are to most laypeople that do not have a PHD in electronics. Are these not what we are talking about? (note the search term used was not AVS or AVR as nothing comes up)

https://www.lazada.co.th/catalog/?q=ups ... 719ctkqCPu

No, they are three different pieces of equipment:

AVS: layman's terms; this tries to keep the voltage within a SMALL set range electronically using mainly capacitors and other small discrete components. Also provides a small amount of filtering to suppress spikes etc. Not really of much use for a house supply, only individual equipment.

AVR: Automatic Voltage Regulator; this is designed to keep a given voltage accurately within the desired range, regardless of whether the supply voltage is lower OR higher than the setpoint, via transformer action in this case. It does not give a stuff about "dirty" voltage supply and provides no filtering.

Grid supplies use transformers with what is termed "tap changers" that switch and change connections to maintain a steady voltage as the load varies.(except in Thailand ) Some of these small units being discussed here also use this method using small relays, but that does not give a smooth output. The better ones use a single winding transformer, usually called a "Variac", with a small motor driven wiper or carbon brush, that smoothly adjusts in a rotary motion to vary the output voltage accurately.

UPS: Uninterruptable Power Supply; this what you normally find a PC plugged into. It has a small internal battery, and inverter, and voltage sensing switching electronics cable of switching in milliseconds. They also provide for SOME filtering of the output. As you know, the household variety are not always up to the task!

As with all things; you get what you pay for!

[Nereus]

An auto transformer is simply a single winding transformer with appropriate taps and can be dangerous if there is an internal short or reversed polarity plus a ground short but is cheapest type to manufacture so household size multi winding transformers are almost non existent these days. A disconected autotransformer can be easily detected with an ohm meter on the taps.

In most developed countries autotransformers are only permitted if permanently internally connected as a part of a piece of equipment. Double wound transformers are still widely used in many types of portable power supplies.

[hin]

A line interactive UPS is a completely different animal and a poor substitute for a proper voltage stabilizer if battery back up is not needed. If you have a UPS with LCD readout you will see that it only stabilizes within some not very close parameters. When power is lost or its buck or boost capability is exceeded it switches from mains to inverter power supplied by its included battery. A 1000VA UPS is typically rated at 500 or 550 Watts because that is the limit of what the battery powered inverter can produce, and only for a very short time at that. The Stabilizer I bought yesterday is 1000VA but rated at 800 Watts with very stable output. So why have a UPS on appliances the do not need battery backup - Like a computer that requires some time to shut it down properly. While on inverter power tho, you will notice the voltage regulation is more stable.

A double inversion UPS does offer almost perfect stability as it completely bypasses mains power but does rely on battery so is limited by battery capacity when mains power is lost. They normally cost ฿15,000 and up and I have never known anyone who had one. They work by having an inverter to keep the batteries charged, usually at least 24 volts and a 2nd inverter to supply power to the computer. The computer never sees mains power. But if you get the kind of voltage spikes we somtimes get it might be an expensive investment going up in smoke unless you place a sacrificial stabilizer upstream of it

4 or 5 years ago we were having big problems here but intermittent so hesitated to call the power company knowing it would probably be fine wen they come to check so just blow me off. But finely put a Fluke meter on line over night set for hi low recording. It read as low as 135v and as high as 298v. And that same night my Mac Book Pro’s power cube got cooked and also the charging circuitry inside the Mac Book. Also a 42” Pamasonic TV got cooked. Wife was watching her 48” TV which was protected by a Koss 1000VA voltage stabilizer I bought about 15 years ago in Malaysia. The Koss shut down and made some smoke but that TV suffered zero consequences. The Koss emitted that expensive smell for a couple months but is still working and we are still using it every day. When the power company guys came the power was still a bit high, I showed them the readings on my Fluke meter and about an hour later 2 guys in suits and ties came by to talk nice ro us. They said there was a bad transformer and within a couple hours it was replaced.

A couple weeks later we went to Penang and bought 4 more Koss 1000VA stabilizers. They do have adequate transformers, not just capacitors, we are still using them, trouble free, so if they are NFG we are quite happy to have them be that. The Koss model we have is no longer produced but the Zircon we bought yesterday is probably better altho physically larger.

[buksida]

Ok, that is all very informative. So what would you suggest for my needs? Expensive PC needs protecting from daily power outages. I've tried standard UPS units and they get fried after a few months and don't really want to spend more on a box than the computer is worth! May as well just use a high spec laptop on battery.

I have another issue that may warrant its own thread but it is power supply related. The PC will not come on at home but it works when I take it to the shop (tried in both JIB branches in Chumphon and Hua Hin and they get it running). Yeah, I know it sounds obvious but I've tested the supply and it is 228 volts, the power cable works on other devices, and the PSU is a gold rated 750 watt Coolermaster unit that wasn't cheap (also works in another PC). The 500VA UPS that I had with it originally is now toast.

I'm leaning towards moving house as the only solution ...