Power cuts

[Bristolian]

I've had to buy 3 battery backups to get my sensitive electronic gear through the frequent but short power blips. They beep a couple of times and stop so if I didn't have them the PVR, TV receiver, and the computer would crash daily... well worth the investment.

I agree, I have done the same to protect my AV equipment I installed a UPS with surge protection. Before i installed the UPS my amplifier was fried on three separate occasions. As you say, it bleeps once in a while but more often i hear a click and the tv picture flickers for a millisecond. Since the UPS/power surge unit was installed i have had no further problems with my amp or other equipment connected.

[Dannie Boy]

I've had to buy 3 battery backups to get my sensitive electronic gear through the frequent but short power blips. They beep a couple of times and stop so if I didn't have them the PVR, TV receiver, and the computer would crash daily... well worth the investment.

I agree, I have done the same to protect my AV equipment I installed a UPS with surge protection. Before i installed the UPS my amplifier was fried on three separate occasions. As you say, it bleeps once in a while but more often i hear a click and the tv picture flickers for a millisecond. Since the UPS/power surge unit was installed i have had no further problems with my amp or other equipment connected.

Where do you install the UPS, is it a plug in for a specific device or can it be installed to protect the whole electrical system?

[dtaai-maai]

My UPS has two or three sockets to connect with devices, but the computer obviously needs more that. I therefore have a 4-socket adapter plugged into the UPS and that has done the trick for several years now.

[Bristolian]

My UPS/surge protector is local and like dtaai-maai, it has 3 or 4 outputs. others may disagree but you really only need this type of device to protect delicate electronics or to provide time to shut down a PC for example without losing data.

[Nereus]

Is it possible to fit circuit breakers to protect against surges ? I recall I did something like that in the UK to protect my television against lightening ( after the house had been struck By a flash off course)

Circuit breakers will not protect against a "surge", or voltage transient spike, as they are mostly designed to protect against over current, or under voltage, and the operating rise time is too long for them to be effective. A surge or spike transient, has a rise time of only a few milli-seconds, such as you will see with a lightening strike. The damage is done before any circuit breaker can react.

What will work is a device called an MOV(Metal Oxide Varistor). These are desgned to be static at "normal" voltage ratings, but have an instantaneous reponse when the voltage rises above the design set point. They will "clamp" the transient by providing a zero resistance path, either across the supply lines, or to ground if of that type.

A UPS will provide some protection depending on how good it`s filtering circuitry is. But their main fuction is to provide protection against supply failure, rather than filtering.

There seems to be many case of short duration supply interuptions in Thailand. I have the same problem in Bangkok, where the supply fails just long enough to kick in the Condo emergency generator(and kill my computor ).

There are a multitiude of reasons that could be causing this to happen, but it should be remembered that the supply is via one big "grid", and that grid is split via a multitude of circuit breakers. The management of what goes where is not automatic, but under the control of various "managers". This also might explain why one area has frequent interuptions, while other areas do not.

The supply grid also consists of many transformers that reduce the supply voltage down from the transmission lines to local requirements. Most transformers have what is called "tap changing" built into them. This feature enables the transformer to adjust the windings to assist voltage regulation as the load changes. While modern transformers use solid state switching to achieve this, many older type have mechanical switches, that may or may not work correctly.

[migrant]

So what is the best way to set up the electronics?

[Jaran]

So what is the best way to set up the electronics?

Not quite sure how the whole electric system is built up here. Im working as an electrician in Norway. Pretty big diffrence back in Norway from Thailand.

In Norway we set up surfe supressors in the fusebox to protect the system for high voltage and so on caused by lightning. This does not protect the components plugged in to the system(TV, PC, and so on). The surge supressor makes sure the system don't melt down. To protect components as TV, PC and so on we use a minor surge supressor that basicly just looks like an adapter. You plug the adapter i to the power outlet, and then connect to component of your liking to the adapter.

[Nereus]

So which one of you lot arranged the following?

Just after 6-00 pm last night there was an almighty "BANG" near my Condo in Bangkok, followed by darkness! It was just on 9-00 pm before power was restored.

From what I could find out this morning an "animal" shorted out the HT line causing the fault. This has happened many times around here, sometimes caused by a stray cat, or, hopefully, a stinking pidgeon!

What I should have mentioned in my post is to beware of what is termed a "brown-out", rather than a black-out. In the case last night the voltage dropped to around 140 / 150 volts, which is still enough to light up a lamp. But it can and will damage anything with a winding in it, such as a refrigerator or a water pump, etc. Better to unplug those types of things until you have bright lights back on again.

[Bristolian]

So which one of you lot arranged the following?

Just after 6-00 pm last night there was an almighty "BANG" near my Condo in Bangkok, followed by darkness! It was just on 9-00 pm before power was restored.

From what I could find out this morning an "animal" shorted out the HT line causing the fault. This has happened many times around here, sometimes caused by a stray cat, or, hopefully, a stinking pidgeon!

What I should have mentioned in my post is to beware of what is termed a "brown-out", rather than a black-out. In the case last night the voltage dropped to around 140 / 150 volts, which is still enough to light up a lamp. But it can and will damage anything with a winding in it, such as a refrigerator or a water pump, etc. Better to unplug those types of things until you have bright lights back on again.

Thanks for the tip regarding voltage drop. I have already isolated my pool and jacuzzi pumps because of this. My house is on a 3ph supply and often you hear the transformer explode. I run firstly to see which if any phases are still working and then run around switching off vulnerable equipment. Strangely I seldom experience a total failure of all 3 phases.

[brianks]

Yes it is possible to purchase Surge Protectors for your house electrical system. After having a surge take out a TV, True box and Modem in our rental house, we had a Safe-T-Cut surge protector installed with our power panel in our new house. I am sure you could find one at Home Pro, Boontavorn, Thai Watsadu or a good electrical supply house. Talk to a good electrician and I am sure they can help.

You guys complaining about a few minutes of power outage make me sick. Down south when it goes down its usually for a couple of hours. Got so bad that I finally installed a electrical generator and wired it into our electrical system so we would not be without power for the extended periods. Of course here in Khanom we also have a major power plant that also supplies power to Koh Samui and Koh Phanagan. With a local power plant you wonder why there are so many outages. A few weeks ago the army visited the local PEA to ask them the same question.

[Big Boy]

You guys complaining about a few minutes of power outage make me sick.

I don't recall complaining, so please don't be sick on my account. I was answering a question, and I don't think I complained once.

[hhfarang]

You guys complaining about a few minutes of power outage make me sick.

I don't recall complaining, so please don't be sick on my account. I was answering a question, and I don't think I complained once.

Me either, I just acknowledged the problem exists and offered a simple solution to protect sensitive electronics.

[Nereus]

Strangely I seldom experience a total failure of all 3 phases.

It will depend on just what type of fault it is, and where it is on the grid. If there is a major fault on the section of grid where you are it will more than likely trip a feeder circuit breaker, and result in a complete black out.

What is more common here is the loss of just 1 phase. But again,the result will depend on where it fails. The system is constructed using a connection configuration called "Delta" on the primary side of all transformers.(If you draw an equilateral triangle, or a diamond, you can see the shape). Each supply phase is connected to one of the 3 apexes. If 1 supply phase fails there is still a circuit through the windings, but because the ratio of the number of turns in the winding, with respect to the secondary side, has now changed, the voltage output of the secondary is reduced. This is what usually results in a "brown out".

The secondary side of the transformer is connected in "star", or a Y shaped configuration.
The 3 outer points of the Y are the three phases fed to the consumer, at the nominated voltage of the transformer. The big difference with this type of connection is that the centre point of the Y, the "star point", is also used and is termed the "neutral". The voltage between any 1 single phase and the neutral is 1.732 of the phase to phase voltage. So on a 380 volt 3 phase supply the single phase voltage is 220 volts.

If 1 of the 3 phase secondary supply lines fail the other 2 are still getting the correct voltage from the primary side, and hence will still be at full voltage. The 3 windings in the secondary side of the transformer can be regarded as 3 seperate single phase transformers, with only the star point of each being connected together. This is why, in a properly connected system, some lights, and or outlets, will still be normal. It is only the 3 phase equipment that will suffer.

Hope that is a bit of a help.

[Bristolian]

Many thanks. Its a long time since I covered basic electrics in my mechanical apprentiship but your explanation is very clear and actually brought back memories of my electrical lecturer, he was Welsh with a very strong accent I still can remember Kirchhoff's circuit laws but only with a welsh accent in mind

I was tempted at one stage to have a 3 pahse supply to my hobby workshop but resisted temptation and finally bought single phase machinery.

[Gregjam]

Had a power failure last night in Roowamsook. As usual it was only one of the phases (the one serving our house). Usually they happen during the day and apart from in the past during the rainy season they occur when people are up and around.
What would like to know is if there is an out of hours contact number to report it. Perhaps someone who knows about the systems here will be aware if such a failure automatically triggers an alarm or does some sort of notification has to be made. Also, if it is just a temporary overload does the system automatically reset or does a man have to physically reset a switch.