Jump to content

Voltage Levels Are Shockingly High


Recommended Posts

My core question is when does overvoltage become hazardous to electronic devices.

 

 

The rest of this posting is merely backstory blather.

 

There are a cluster of residences in the area where I live. We receive our electricity via a power line strung from a small village about one kilometer away. For years we suffered from undervoltage issues. Pleasantly surprised when the Provincial Electricity Authority (PEA) upgraded the grid and installed a transformer 500 meters away.

 

Things were fine for a time – but as the number of residences increased in our area - so did power consumption. A kindly PEA technician upped the voltage from 220 volts to 230 volts to accommodate a voltage drop of up to or over 20 volts during times of peak demand.

 

Voltage levels from the PEA have varied – kind of like bipolar mood swings. There have been intermittent periods when the voltage range drops to 200-220 – then rising back up a day or so later.

 

A few months ago the peak voltage levels went from being 230 volts to being 240 volts.

For the past couple of weeks the voltage tends to get even higher (242-247 volts) – occasionally pushing 250 volts.

 

Not certain if this is another voltage mood swing or if the power levels are going to stay crazy.

I remember reading the Thai government considered sending extra electricity because people were working from home due to Covid-19.

 

The PEA technician who previously adjusted our voltage - no longer works for the PEA. The current team of PEA technicians seem less approachable. I am concerned about the outcome of making adjustments to the voltage. PEA may not wish to send more than 220 volts or add more voltage as future demand increases. A recent influx of new construction near us reflects amenitized resort style homes - not the primitive farmhouse architecture common to the area.

 

I have experienced three types of electrical whining - me complaining about not enough volts - me complaining about too many volts – the sound emitted by a fluorescent light ballast freaking out (overwhelmed by too many volts). That annoying noise can only be eclipsed by the clatter of a fluorescent light gasping for enough juice to ignite its tube (not enough volts).

 

 

Hoping for help from those knowledgeable in the field of electricity. At what levels does overvoltage become a hazard to all things electrical?

  • Like 1
  • Haha 1
Link to post
Share on other sites

I am not an expert but as far as I know many devices allow up to 240V.

And I am sure they all have an extra margin. Add i.e. 3% to 240V and you have already 247V.

Not perfect but personally I don't think you have much to worry about.

Often too low voltage is a bigger problem.

  • Like 2
Link to post
Share on other sites

Most equipment will be good from about 198V (220V -10%) to 253V (230V +10%) with a bit on top for safety (PEA is 220V, MEA 230V).

 

I would certainly keep an eye on it and if it keeps climbing have a word with PEA. It's possible a big load has gone off-line (factory) and everything will go back to normal when they start work again.

  • Like 2
Link to post
Share on other sites

Anecdote:  About 6 years ago, our local voltage began going into the 240-250V range to accommodate a new water purifying factory.  At 250V and above, my smart TV would shut down, my AC wouldn't start, fans on steroids, and my refrigerator made abnormal noises until it finally died.  (Easily fixed after the local guy replaced something.)

 

Anyway.... That's when I bought my first AVR(AVS) and no issues since.  Now, the mains voltage stays in the 230's but the AVR's maintain between 218-224.

  • Like 2
Link to post
Share on other sites
5 hours ago, humint said:

My core question is when does overvoltage become hazardous to electronic devices

  

5 hours ago, humint said:

My core question is when does overvoltage become hazardous to electronic devices

Many, but not all electricity authorities consider 10% fluctuations acceptable, on a 220v system that's 22 volts, up or down.! And thus on a 240v system that's 24v.

Most, but not all white goods use common motors, that is motors capable of running on 190v-260v or 90v-140v, this is to save costs, making specific motor for 220v (Europe, Asia and some pacific countries) and for 240v (UK Australia and NZ) and 90v-110v (some sub Saharan African and south American countries) and 110v-140v (US and Canada) is more expensive.

Therefore where universal motors are used and allowing for fluctuations (10%) most can run OK up to 260v, possibly even more.

Electronics are similar, look at your laptops power supply, most these days specify voltages of between 80v and 260v or 90v to 250v.

Thus most modern equipment can withstand over and under voltages OK.
Not always guaranteed.

A recording volt meter can be handy to determine the time most often when over voltages occur, these would obviously be times when it could be prudent to avoid using sensitive equipment.
 

  • Like 1
Link to post
Share on other sites

I would be more concerned with transient high voltage spikes, especially during lightning storms. I protect all of my sensitive devices with a voltage controlled UPS (uninterrupted power supply). I few years ago, my Onkyo receiver was severely damaged during a storm as the power was glitching on and off…

  • Like 1
Link to post
Share on other sites
Posted (edited)
6 hours ago, Crossy said:

Most equipment will be good from about 198V (220V -10%) to 253V (230V +10%) with a bit on top for safety (PEA is 220V, MEA 230V).

 

I would certainly keep an eye on it and if it keeps climbing have a word with PEA. It's possible a big load has gone off-line (factory) and everything will go back to normal when they start work again.

Crosby, thank you for your valuable input.

 

The first voltage increase would correspond to the end of sugarcane season and the closure of sugarcane processing plants in our region. The return of the extra electricity allotted to the sugarcane factories is generally offset by the onset of warmer weather and increased demands of fans and ACs. This summer the weather has been milder.

 

The second voltage bump might be related to the other industry in our area – resorts and homestays. Due to Covid-19 lower occupancy rates. Fewer guests using ACs, TVs, hot water heaters, etc.

 

After many years of coping with undervoltage it is ironic to be contending with overvoltage.

Guess the old adage “be careful what you wish for” might apply to my current situation. I plan on being more specific in my future prayers.

Edited by humint
  • Like 2
Link to post
Share on other sites
4 hours ago, Dazinoz said:

If the voltage is increased the amperage increases.

?       It goes Down 

2000 Watt at 200 Volts =10 Amp   2000 Watt at 240 Volt =8.3333333 Amp

  • Like 1
Link to post
Share on other sites
6 hours ago, bankruatsteve said:

Anecdote:  About 6 years ago, our local voltage began going into the 240-250V range to accommodate a new water purifying factory.  At 250V and above, my smart TV would shut down, my AC wouldn't start, fans on steroids, and my refrigerator made abnormal noises until it finally died.  (Easily fixed after the local guy replaced something.)

 

Anyway.... That's when I bought my first AVR(AVS) and no issues since.  Now, the mains voltage stays in the 230's but the AVR's maintain between 218-224.

You shouldn't have to do that and depending on how many appliances you have it get downright expensive.

 

I would go down with your wife and a few neighbors to make a complaint at the main office.

 

Fluctuating current over time will shorten the life span of any appliance.

Link to post
Share on other sites
10 hours ago, humint said:

The first voltage increase would correspond to the end of sugarcane season and the closure of sugarcane processing plants in our region. The return of the extra electricity allotted to the sugarcane factories is generally offset by the onset of warmer weather and increased demands of fans and ACs. This summer the weather has been milder.

 

The second voltage bump might be related to the other industry in our area – resorts and homestays. Due to Covid-19 lower occupancy rates. Fewer guests using ACs, TVs, hot water heaters, etc.

 

Yeah, that makes a lot of sense. So the chances are good that things are going to return to lower voltage levels "in future" and also that it's probably not going to get any higher.

 

Our own power consumption is certainly down on the same time last year.

 

We do actually have a whole-house AVR, thread here :- https://forum.thaivisa.com/topic/1008193-installing-an-automatic-voltage-regulator-avr/ which could be an option if you are worried but I think you will be fine.

 

Link to post
Share on other sites
10 hours ago, MrJ2U said:

You shouldn't have to do that and depending on how many appliances you have it get downright expensive.

Do what?  I have no "it" that gets expensive.

Link to post
Share on other sites
11 hours ago, digger70 said:

?       It goes Down 

2000 Watt at 200 Volts =10 Amp   2000 Watt at 240 Volt =8.3333333 Amp

Sorry but wrong.

 

The amps through an appliance is a factor of the resistance (impedance) of the appliance and the voltage applied to it. The rated wattage of an appliance is at rated voltage. If the voltage goes up, the impedance stays the same so the amps go up and hence the wattage. 

 

In the example you give the resistance would be seen as 20 ohms (Resistance=Volts/Amps). So when voltage increases to 240 volt the current would increase to 12 amps (Amps=Volts/Resistance).

 

As I said the rated wattage of an appliance is at rated voltage. The resistance (impedance) of the appliance does not change so if the voltage goes up so does the amps and also the watts consumed.

 

 

Link to post
Share on other sites
2 hours ago, Crossy said:
13 hours ago, humint said:

The first voltage increase would correspond to the end of sugarcane season and the closure of sugarcane processing plants in our region. The return of the extra electricity allotted to the sugarcane factories is generally offset by the onset of warmer weather and increased demands of fans and ACs. This summer the weather has been milder.

 

The second voltage bump might be related to the other industry in our area – resorts and homestays. Due to Covid-19 lower occupancy rates. Fewer guests using ACs, TVs, hot water heaters, etc.

 

Yeah, that makes a lot of sense. So the chances are good that things are going to return to lower voltage levels "in future" and also that it's probably not going to get any higher.

 

Our own power consumption is certainly down on the same time last year.

 

We do actually have a whole-house AVR, thread here :- https://forum.thaivisa.com/topic/1008193-installing-an-automatic-voltage-regulator-avr/ which could be an option if you are worried but I think you will be fine.

 

This time last year, I would have given my left nut for a bit of evening over-voltage. After over 12 years of at-best 170 V most summer evenings and endlessly beeping UPS's and fruitless conversations with the local PEA, I was at the end of my tether.

 

Just over two months ago, I was a 5-minute drive away from buying an AVR when I noticed the PEA guys working on the recently installed HV lines less than 300 meters from the house. These had been spreading around us over the previous 18 months including a new sub-station on the other side of the ring-road but we seemed doomed to be on the end of the creaking, ancient power distribution system that saw our feed transformer blow up regularly only to be replaced by one of the same capacity.

 

When I got back home, Mrs NL confirmed that the power had been off for about 3 hours already. When it came back on a little before 6 p.m., I checked the UPS display and it showed a steady 217 instead of the usual 200-ish and falling. That evening, it stayed up around 217 all night and we managed to run two air-conditioners and there was no need to stagger the shower use. I mentioned it to my neighbor the next morning and he too remarked that he didn't have the usual issues with his upstairs air-conditioning. About 5 days later, evening voltages returned to their usual lows and we thought that was good while it lasted. However, about 10 days later, after another afternoon outage, we saw 223 volts supply that only dropped to around 219 and all was good. Fridges were refrigerating, freezers were freezing and everyone was happy that they didn't need to run around turning appliances off so we could have dinner.

 

My biggest beef with PEA was when I was on an online chat during a particularly bad 146 volt episode. They apparently have an auto-sensing, load-sharing network that monitors the grid and they said they could see nothing wrong on our 'node'. I do believe that their monitoring systems are there but maybe only installed on newer, more accessible grids and the older power line monitoring is less granular? Those two outages were probably to get us switched to the newer grid and do some manual load-sharing. Since then, maybe two months already, the voltage has been so boring and normal, we've stopped talking about is and thus, so will I.

 

 

  • Like 1
Link to post
Share on other sites
2 hours ago, Rampant Rabbit said:

 

Check the voltage reset times for these devices. Older, non-inverter fridges and air-conditioners use a compressor that ideally needs about 2-3 minutes before restoring power after outage or being unplugged. AFAIK, newer inverter units are more resilient?

Link to post
Share on other sites
27 minutes ago, SAFETY FIRST said:

Look at the bright side. 

You're drawing less current. 

If the voltage is higher you draw more current. Read my post above.

Link to post
Share on other sites
12 hours ago, CH1961 said:

Since decades (1983) the voltage in Europe is 230 VAC +/- 10%

Minor pedantics.!

Europe converted from 110v to 220v starting in the early 1970.

Many electricity authorities add an extra 10v as a means of cheaply adding extra capacity without actually updating infrastructure.

It's a common practice.

Point remains, many manufacturers now use universal motors rather than voltage specific motors.

Link to post
Share on other sites
2 hours ago, Dazinoz said:

The resistance (impedance) of the appliance does not change

Being picky................ only with an ohmic resistor would the resistance not change with current.......a filament lamp's resistance increases quite markedly with the current......as I say....being picky.

Link to post
Share on other sites
16 minutes ago, Surelynot said:

Being picky................ only with an ohmic resistor would the resistance not change with current.......a filament lamp's resistance increases quite markedly with the current......as I say....being picky.

Obviously you the expert so I say no more except I trying to keep it simple.

  • Like 1
Link to post
Share on other sites
1 minute ago, Dazinoz said:

Obviously you the expert so I say no more except I trying to keep it simple.

Ha....far from an expert......just happen to be part of the syllabus I taught in Germany.

Link to post
Share on other sites
3 hours ago, Dazinoz said:
3 hours ago, SAFETY FIRST said:

Look at the bright side. 

You're drawing less current. 

If the voltage is higher you draw more current. Read my post above.

The power rating of the electrical appliance remains constant. 

 

Ohms law E=IR, P=EI

 

If the voltage increases you must get a decrease in current. 

The power rating cannot change. 

Link to post
Share on other sites
7 minutes ago, SAFETY FIRST said:

The power rating of the electrical appliance remains constant. 

 

Ohms law E=IR, P=EI

 

If the voltage increases you must get a decrease in current. 

The power rating cannot change. 

As Crossy has pointed out previously...


"Pure resistive like a water heater as the volts go up so does the current (and the power).

 

Constant power like a PC or an "inverter" device then as the voltage goes up the current goes down (power is constant)."

  • Like 1
Link to post
Share on other sites

As others have noted few modern loads actually follow the simple ohm's law rules.

 

Purely resistive loads like water heaters will, so an increase in supply voltage will result in an increase in supply current and a corresponding increase in power (your water will be hotter).

 

Most electronic loads are "constant power", so increasing the supply voltage actually reduces the current with the power remaining constant.

 

Induction motors (water pumps, conventional A/C) are even more fun. Over volting them doesn't increase the power consumption, but it does mess with the power-factor increasing the current draw so W no longer = VI (this is where VA ratings come into the picture).

Link to post
Share on other sites

I do not wish to appear as an ‘original poster” (OP) that posts and disappears.

A special thank you for all your replies to my question about overvoltage.

 

When I asked for help from those knowledgeable in the field of electricity – just like my overvoltage problem – I now have more (information) than I know what to do with.

While attempting to assimilate some of the more technical posts - I realized my brain’s directory does not even have a listing for electrical technology.

The takeaway being I should probably not attempt any DIY electrical projects.

Sadly my two go-to guys (electricians) are no longer around.

 

Kudos for your help.

Link to post
Share on other sites

I think as stated previously you are on a single phase 230 v 50 Hz feed from a PEA sub-station distribution electrical network.

 

When the power factor is 1.0 and all 3 phase feeds are phased balanced from the substation's HV to LV transformer, each output single phase feed will deliver the nominal supply mains voltage of 230 volts.

 

Commercial or industrial organizations requiring 3 phase feeds on the same HV to LV transformer for industrial 3 phase devices or sheer single phase loading requirements can impact the power factor. 

 

To incur the voltage variations of 200 (-13.34%) to 250 (+21.74%) volts from the nominal supply voltage of 230 volts (assume your neighbours on the same supply feed are experiencing similar variations) is significant.

 

With the transformer only 500 meters from your property the +250 volt swing is well outside of the EGA Thailand specifications. 

 

image.png.97a53a5ad083ca898996959103f8102d.png

https://www.pea.co.th/Portals/0/Document/vspp/PEA%20Interconnection%20Code%202016.pdf

 

I assume the transformer installed 500 meters from your property is a line buck-boost transformer.  

 

A well designed buck - boost transformer should have a controlled feedback loop to control any under / over voltage output swings above a selectable level (e.g. 230 volts).

 

Units are rated in volt-amperes (most commonly, kilo-volt amperes KVA) (or more rarely, amperes) and are rated for a percent of voltage drop or rise.

 

For example, a buck–boost transformer rated at 10% boost will boost a supplied voltage of 208 V AC to 229 V AC.

 

A rating of 10% buck will yield the result of 209 V AC if the actual incoming supplied voltage is 230 V AC.

 

The original problem could be attributed to phase loading variations from the other two phases impacting your phase on your property. 

 

The buck - boost transformer should have mitigated the issues you described.

 

Not sure other then to request in writing from PEA the buck–boost transformer specifications; based on that information you could determine the transformer cannot do the job or is not configured correctly.

 

Or as a  last resort request them to place a load monitoring device on the 3 phase output of the mains HV to LV transformer feeds and record the power factor, frequency and voltage variations and current load distribution while at the same time monitoring the voltage and current load on the the output of the buck-boost transformer 500 meters from your property.

 

 

 

 

 

 

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...