what voltage are you running? 220V / 230V / 240V?

[SilverNodashi]

Something came to mind recently, and I was rather curious, what output voltages do people run on their inverters? The default, which should be 230V, or do you adjust it down to 220V, or up to 240V?

Why the question?

Well, this is where my thought comes from: Could some appliances use less electricity (Read: Watts / Wh) if it runs at a higher voltage? Most electronics don't have advanced MCU's and algorithms like an MPPT charge controller, but it would most probably still "negotiate" the energy needs based on the input voltage. 

A Satchell 2000W geyser element, rated at 220V has a resistance of 22.8Ohm. With a constant resistance, if you apply 230V, it will consume 10.08A and produce 2320W. At 220V :: 9.65A & 2122W and at 240V :: 10.53A & 2526W. 

These formulas would work the same for normal light bulbs, but I'm not sure how it would affect LED lights since LED lights normally have a buck booster to step down from 220V to 12V

SO, at lower voltages with the same resistance, you effectively use less electricity / less energy. 

Other electronics work differently though since most electronics (Read: TV / computer / gate motor / fridge / etc) have a transformer to step down from 220V-240V to it's desired operating voltage, which is generally 12V or 5V.

 

* I don't take scale build-up or volt drop into account right now since it would differ from house to house. 

@plonkster Please correct me if I'm wrong

[___]

Far as I know all electrical motors and anything with a switch mode PSU will compensate a lower voltage with a higher current, so there is little advantage to running at 220. Only the resistive appliances will use less, like the geyser, stove and kettle, and they also take longer to do their job when they run at the lower voltage so that there is no benefit. The only thing this worked with, back in the day, was incandescent lamps... and we're well past those.

So I run at the standard 230. Well, I'm mostly grid tied these days so more like 237 :-)

Sent from my GT-I9195 using Tapatalk

[SilverNodashi]

53 minutes ago, plonkster said:

Far as I know all electrical motors and anything with a switch mode PSU will compensate a lower voltage with a higher current, so there is little advantage to running at 220. Only the resistive appliances will use less, like the geyser, stove and kettle, and they also take longer to do their job when they run at the lower voltage so that there is no benefit. The only thing this worked with, back in the day, was incandescent lamps... and we're well past those.

So I run at the standard 230. Well, I'm mostly grid tied these days so more like 237 :-)

Sent from my GT-I9195 using Tapatalk
 

Yes that confirms my earlier statement, though I didn't include motors. 

BUT, if an electrical appliance with a transformer detects lower voltage, say 220V, would it really draw more current to satisty it's needs? Or would the SMPS still output it's desired energy, since it already runs on such a higher input voltage?

 

I don't have the equipment right now to test this exactly, but would like to see what happens to say a fridge or TV if you drop the input voltage to 220V. Would it still operate as usual, drawing the same Ampere, or does it draw more input Ampere to satisfy the desired output Ampere?

[___]

3 hours ago, SilverNodashi said:

BUT, if an electrical appliance with a transformer detects lower voltage, say 220V, would it really draw more current to satisty it's needs? Or would the SMPS still output it's desired energy, since it already runs on such a higher input voltage?

It depends. If it uses a proper old-school iron transformer running at 50hz, and there are no special regulation circuitry downstream or the electronics are all linear (ie regulation happens by wasting the excess voltage times current as heat), then it will use less power at a lower voltage. The transformer is after all a fixed ratio, so lower input translates to a lower output.

If it is a SMPS, then the transformer is much smaller and runs at a higher frequency, and the ratio is not fixed: There is a feedback loop that regulates the output voltage by changing the PWM ratio on the input side. Lower input voltage will just lead to a higher PWM ratio to get the same output voltage, and therefore the same power.

Check out this video by bigclive. He explains some of it at around 13 minutes.

 

[Czauto]

Last winter I realised that my UPS was transferring every now and then in peak times (6pm-10pm) This was before my Axpert installation so I had no monitoring software or anything to check any historic data. I installed a Volt/Ammeter between my prepaid meter and DB and after confirming readings with a digital multimeter realised that my Grid supply voltage was sometimes as low as 192V. Well that was the lowest I've tested it seeing that there was no other means of monitoring. One night I went nextdoor to my neighbor one night and tested his supply and got the same low voltage as mine (both supplies from the same electricity pole) I complained at the council's electricity dept and not sure what they did to remedy the problem but it seems stable now. One should never assume Grid supply to be stable, never.

Today, just as I was setting up the pressure washer to clean a client's engine, my neighbor shoved his head over the wall and told me that it was not going to work because apparently the whole town's electricity has been off for more than two hours. I looked him straight in the eyes with a very smug smile on my face and started pressure washing the engine. I watched in the corner of my eye as he turned around and went inside. After about two minutes of pressure washing I started drying the engine and my 200ltr, 2.2Kw compressor started. By this time neighbor was outside again watching very confused. After I finished I closed the bonnet and he asks me "buurman nou hoekom werk jou goed en myne nie?" I just pointed my eyes up to my panels and said nothing. Is there any pleasure better than to hear generators start and people complaining about blackouts and all your unnecessary, expensive "shit" (sorry for that) just works like everyday.

In the end we had a blackout for more than three hours and I had no disruption at all on this sunny day. SOC didn't even go below 98%.

Sort of like the Visa ad.

Axpert 5Kva = R10800, PV array = R12000, Batteries = R14000, Look on neighbor's face when there's a blackout at HIS side of the fence and not yours? PRICELESS!!

[SilverNodashi]

3 minutes ago, Czauto said:

Last winter I realised that my UPS was transferring every now and then in peak times (6pm-10pm) This was before my Axpert installation so I had no monitoring software or anything to check any historic data. I installed a Volt/Ammeter between my prepaid meter and DB and after confirming readings with a digital multimeter realised that my Grid supply voltage was sometimes as low as 192V. Well that was the lowest I've tested it seeing that there was no other means of monitoring. One night I went nextdoor to my neighbor one night and tested his supply and got the same low voltage as mine (both supplies from the same electricity pole) I complained at the council's electricity dept and not sure what they did to remedy the problem but it seems stable now. One should never assume Grid supply to be stable, never.

One of the subburbs in our town, last year, had a problem at the substation and everyone received 400V electricity. For free Most people lost TV's, fridges, gate motors, etc, etc. So, for that very reason, "One should never assume Grid supply to be stable, never.", it is always better to use an inverter,or even a UPS to ensure stable voltage on your end. 

 

3 minutes ago, Czauto said:

Today, just as I was setting up the pressure washer to clean a client's engine, my neighbor shoved his head over the wall and told me that it was not going to work because apparently the whole town's electricity has been off for more than two hours. I looked him straight in the eyes with a very smug smile on my face and started pressure washing the engine. I watched in the corner of my eye as he turned around and went inside. After about two minutes of pressure washing I started drying the engine and my 200ltr, 2.2Kw compressor started. By this time neighbor was outside again watching very confused. After I finished I closed the bonnet and he asks me "buurman nou hoekom werk jou goed en myne nie?" I just pointed my eyes up to my panels and said nothing. Is there any pleasure better than to hear generators start and people complaining about blackouts and all your unnecessary, expensive "shit" (sorry for that) just works like everyday.

In the end we had a blackout for more than three hours and I had no disruption at all on this sunny day. SOC didn't even go below 98%.

Sort of like the Visa ad.

Axpert 5Kva = R10800, PV array = R12000, Batteries = R14000, Look on neighbor's face when there's a blackout at HIS side of the fence and not yours? PRICELESS!!

 

When you add cables, brackets, fuses, change over switches and a COC, it's a bit more expensive. But, yes, I agree, it's a nice feeling to be able to continue working while others sit in the dark  Mate of mine had a blackout on Friday, was forced to braai and shower at his folks place. We continued our happy lives. 

 

[Gnome]

On 5/2/2017 at 3:19 PM, SilverNodashi said:

One of the subburbs in our town, last year, had a problem at the substation and everyone received 400V electricity. For free Most people lost TV's, fridges, gate motors, etc, etc. So, for that very reason, "One should never assume Grid supply to be stable, never.", it is always better to use an inverter,or even a UPS to ensure stable voltage on your end. 

Sadly, this is probably due to a broken neutral. 99% of substations in South Africa are delta-wye three phase transformers. In case of a broken neutral your voltage can vary anywhere from ~0-480v depending on the load distribution.

This situation is more common in SA than it should be due to cable theft.

On 5/2/2017 at 3:10 PM, Czauto said:

I installed a Volt/Ammeter between my prepaid meter and DB and after confirming readings with a digital multimeter realised that my Grid supply voltage was sometimes as low as 192V. Well that was the lowest I've tested it seeing that there was no other means of monitoring. One night I went nextdoor to my neighbor one night and tested his supply and got the same low voltage as mine (both supplies from the same electricity pole) I complained at the council's electricity dept and not sure what they did to remedy the problem but it seems stable now. One should never assume Grid supply to be stable, never.

Should also not be very common. I would guess this would probably be more common in outlying areas or the especially rural areas.

The load regulation up until the substation is usually really good. But in SA some of these substations don't get much love.

[ojeysky]

On 2017/05/02 at 7:47 AM, SilverNodashi said:

Something came to mind recently, and I was rather curious, what output voltages do people run on their inverters? The default, which should be 230V, or do you adjust it down to 220V, or up to 240V?

Why the question?

Well, this is where my thought comes from: Could some appliances use less electricity (Read: Watts / Wh) if it runs at a higher voltage? Most electronics don't have advanced MCU's and algorithms like an MPPT charge controller, but it would most probably still "negotiate" the energy needs based on the input voltage. 

A Satchell 2000W geyser element, rated at 220V has a resistance of 22.8Ohm. With a constant resistance, if you apply 230V, it will consume 10.08A and produce 2320W. At 220V :: 9.65A & 2122W and at 240V :: 10.53A & 2526W. 

These formulas would work the same for normal light bulbs, but I'm not sure how it would affect LED lights since LED lights normally have a buck booster to step down from 220V to 12V

SO, at lower voltages with the same resistance, you effectively use less electricity / less energy. 

Other electronics work differently though since most electronics (Read: TV / computer / gate motor / fridge / etc) have a transformer to step down from 220V-240V to it's desired operating voltage, which is generally 12V or 5V.

 

* I don't take scale build-up or volt drop into account right now since it would differ from house to house. 

@plonkster Please correct me if I'm wrong

Did you eventually go for 220v or default 230v? am curious to know the difference in this as well

Edited June 28, 2020 by ojeysky

[___]

Really old thread... but...

For resistive loads, like incandescent lamps, kettles and water heaters (aka geysers in SA parlance), running at a lower voltage does lower the power, but it also reduces the light output and/or it takes longer to heat the water. For water heating there would then be no advantage, it would take slightly longer and use the same energy.

Other electronic loads typically have switch mode power supplies and will compensate for the lower voltage by increasing the current draw, so no advantage there either.