Low voltage and a/c

[zlodnick]

We have 2 Mitsubishi a/c units. One 9k btu inverter and one 18k non inverter.

Our neighbor has a rice milling machine that he uses during the day. When the machine is on, it draws down the voltage at our house from 220 volts to anywhere from 185 to 200 volts. If I turn on the a/c when we have 200 volts, then the multi meter shows 195-196 volts. So, I dont like to use the a/c unless we have at least 205 v.

Am I being overly cautious or not? 

[transam]

Perhaps get PEA out to test your supply, it sounds like the mains need bolstering...

[zlodnick]

Not sure about that. When the neighbor isnt using his machine, we usually have 220-230v.

[Crossy]

220V +- 10% (which is sort of guaranteed) is 198V to 242V.

 

In reality, even your non-inverter A/C should be fine down to 185V (-16%).

 

Small AVR (automatic voltage regulator) are readily available which will magic 220V out of 150V, cover just one or two items or your whole house. Pretty well every A/C in Delhi has an AVR next to the indoor unit, power there can be somewhat "variable".

 

[zlodnick]

Thanks Crossy

[OneMoreFarang]

Make sure that the cables to any devices which use a lot of power are big enough.

The required size of the cables depends on the Amps.

If a unit has i.e. 5000W then it uses 22.7A with 220V. And with 195V it would use 25.6A.

W = U * I

You can also lookup brownout and possible consequences. 

[Isan Farang]

6 hours ago, Crossy said:

220V +- 10% (which is sort of guaranteed) is 198V to 242V.

 

In reality, even your non-inverter A/C should be fine down to 185V (-16%).

 

Small AVR (automatic voltage regulator) are readily available which will magic 220V out of 150V, cover just one or two items or your whole house. Pretty well every A/C in Delhi has an AVR next to the indoor unit, power there can be somewhat "variable".

 

I know very little regarding electric stuff, at my location in Chiang Rai the supply appears to be all over the shop, my normal floor fan will run fine and then the speed will drop by half and after some time return to normal.

 

Just checking if its possible to fit a AVR on the main switch box to get a more even supply, my main concern is to the AC type invertor, that i i am sure is not getting a constant supply of required power.

 

In my main house in Ubon i have 3 phase and its either full whack or power off, never have any fluctuations.

[Crossy]

10 hours ago, Isan Farang said:

Just checking if its possible to fit a AVR on the main switch box to get a more even supply, my main concern is to the AC type invertor, that i i am sure is not getting a constant supply of required power.

 

Inverter A/C units are much more tolerant of low voltage than conventional types due to their power supplies being "smart". If you don't already have surge arrestors, I would certainly be looking at installing them, modern inverters are pretty robust (early ones died rather too readily with surges) but every little helps.

 

For whole-house AVRs, have a read here: -

 

[h90]

On 4/12/2023 at 1:13 PM, zlodnick said:

Not sure about that. When the neighbor isnt using his machine, we usually have 220-230v.

We have usually 235, some days it even touch 240. Maybe they can increase on the transformer a bit?