Power factor correction and inverters

[Kawak]

Wanted to find out if anyone is using power factor correction on their solar inverter/generator setup, does it do anything?

My understanding is it will bring the KW closer to the KVA rating of these machines, but does it actually make any difference in real life? Do those tiny units sold online actually work? They seem to just have a small capacitor in them.

 

[B-1]

I once plugged 3 of them in by accident and eskom had to pay me for power consumption.

 

[RedViking]

Sorry OP, I know you asking a serious question, but it reminds me of this:

Power Balance - Wikipedia

en.m.wikipedia.org

 

[Kawak]

Sorry OP, I know you asking a serious question, but it reminds me of this:

View attachment 1211512

Power Balance - Wikipedia

en.m.wikipedia.org

Tesla coils come to mind. If only thats possible.

 

[Kawak]

Going to push my post, really want to know if it makes a difference, trying to understand the strange daily behaviour of my led lights that seem to flicker during dinner prep and then later on at night.

Is this behaviour due to voltage fluctuations and can be helped with these power factor units? I have a feeling these fluctuations are damaging my motors as I can hear how my pumps hum differently during and after these episodes until they cycle off.

 

[Neuk_]

Going to push my post, really want to know if it makes a difference, trying to understand the strange daily behaviour of my led lights that seem to flicker during dinner prep and then later on at night.

Is this behaviour due to voltage fluctuations and can be helped with these power factor units? I have a feeling these fluctuations are damaging my motors as I can hear how my pumps hum differently during and after these episodes until they cycle off.

Power Factor correction is a massive cost saving for large industrial consumers using very large, power hungry, three phase equipment. You may find a very small change in power factor for appliances in your house using an electric motor but I doubt it is worth looking in to proper power factor correction. As @Jaws677 has asked, do you have a pure sine wave or modified sine wave inverter?

 

[Kawak]

Power factor correction is a things yes.
But the product you posted an image of is a load of BS.

It sounds more like you don't have a pure sine wave inverter.

Induction motors don't take kindly to being fed block waves they are more into the whole sine wave scene....

I use axpert inverter which are marketed as pure sinewave and have used them for over 2 years already, motors don't sound strange on them, They would have burst into flames by now if it wasn't, at least, half decent "simulated pure" sinewave.

 

[Kawak]

Power Factor correction is a massive cost saving for large industrial consumers using very large, power hungry, three phase equipment. You may find a very small change in power factor for appliances in your house using an electric motor but I doubt it is worth looking in to proper power factor correction. As @Jaws677 has asked, do you have a pure sine wave or modified sine wave inverter?

Axpert hybrid solar inverter which was marketed as pure sinewave, it's not about cost savings as it's solar, but me wondering if it's because the inverter isn't able to ramp up supply fast enough when my microwave kicks in? Will something like power factor correction help in this case? From the reading on the inverter, the KVA vs KW has an almost constant 110 watt or VA difference, it fluctuates but strangely is much less when I use the oven.

 

[fragtion]

Going to push my post, really want to know if it makes a difference, trying to understand the strange daily behaviour of my led lights that seem to flicker during dinner prep and then later on at night.

Is this behaviour due to voltage fluctuations and can be helped with these power factor units? I have a feeling these fluctuations are damaging my motors as I can hear how my pumps hum differently during and after these episodes until they cycle off.

Does this flickering and humming happen while you're connected to the grid? Sounds like you're seeing the ripple relay system in action, which kicks in on the hour and lasts a minute or two and causes the strange buzzing sounds and dimming effects but is apparently completely normal. That's how they control our hot water geyser relays remotely.

As for the power factor correction. There's a lot of mysticism about power factor correction, but power factor is obviously real and there are real ways of correcting it AFAIK (something to do with capacitors and/or inductors on the AC filter side of your appliances) so improving usage efficiency is definitely something worth looking into IMO

 

[Kawak]

Does this flickering and humming happen while you're connected to the grid? Sounds like you're seeing the ripple relay system in action, which kicks in on the hour and lasts a minute or two and causes the strange buzzing sounds and dimming effects but is apparently completely normal. That's how they control our hot water geyser relays remotely.

Thats interesting, I'll investigate, I do have a hybrid system so do not know exactly when I'm on solar and when I'm on grid but will test this.

Thanks.

Does this daily activity from Eskom damage our motors?

 

[Neuk_]

Axpert hybrid solar inverter which was marketed as pure sinewave, it's not about cost savings as it's solar, but me wondering if it's because the inverter isn't able to ramp up supply fast enough when my microwave kicks in? Will something like power factor correction help in this case? From the reading on the inverter, the KVA vs KW has an almost constant 110 watt or VA difference, it fluctuates but strangely is much less when I use the oven.

Good to hear it is a pure sine wave inverter, far better for your appliances with electrical motors, it shouldn't be the cause of your flickering lights and humming electrical motor issue. I don't think that the issue is power factor either, there is something else causing the issue.

 

[Neuk_]

As for the power factor correction. There's a lot of mysticism about power factor correction, but power factor is obviously real and there are real ways of correcting it AFAIK (something to do with capacitors and/or inductors on the AC filter side of your appliances) so improving usage efficiency is definitely something worth looking into IMO

PFC is quite well understood but is mainly used in industrial settings as the cost versus saving for average households simply doesn't warrant it. My wife's family company offers PFC as part of their Electrical Engineering equipment and services.

RWW Engineering

 

[wingnut771]

Is it not the transfer time of the inverter causing the flickering lights?

 

[Kawak]

Is it not the transfer time of the inverter causing the flickering lights?

Could be, but I have investigated and the inverter cut over time doesn't match. Will also look into this further.

 

[Rickster]

Power factor correction is only really used in businesses that use 3 phase as they get billed in a different way than home consumers.

I think...

 

[Neuk_]

Power factor correction is only really used in businesses that use 3 phase as they get billed in a different way than home consumers.

I think...

You are correct.

 

[Magnum]

Power Factor is wasted power. typically if you run at 86% you are wasting 14% of the generated power. All Coil based appliances give you an Inductive power factor. Causing current to trail the Emf.(Voltage) connecting a Capacitor in circuit will correct the power factor back to 0 when correct size is used. Good luck with that as is changes the whole time. As motors start and stop. microwave, fluorescent tubes/globes. I am not to sure about switchmode powersupplies. Even though they are DC they they do have Caps and Coils on the Primary side.

Still need to scope one of those.

 

[Magnum]

You are correct.

No you het Billed for KVA but get to use KW. You are paying more for power than what you use. Large power consumers pay extra for Power factor because they effect transmissions systems more than residential users. The effect is massive when you start looking at MW rated motors.

 

[Geoff.D]

almost constant 110 watt or VA difference, it fluctuates but strangely is much less when I use the oven

What is the total load? Compare that with the difference and then decide if PF is going to have any effect and benefit.
What is the voltage AND frequency stability like when you notice the motors making funny noises?

Resistive loads are pure loads kW = VA, hence the PF = 1. Adding resistive loads generally stabilises any PF issues. ( makes the difference between kW and VA less significant.)

When the resistive total load is reduced ( no geysers, kettles, etc are running) the inductive loads become more significant, hence it sort of makes sense that you notice these issues at those times.


Do you know that the motors are working properly and do not have capacitors in them that are busy dying on you?

No personal experience of the small devices being sold.

A typical residential load is almost entirely resistive. BUT that changed when we all started using CFL lamps and LEDs and more and more inverters etc.

I presume that it would not require anything substantial to correct any PF issues in a typical home. However, without someone doing some proper measurements first, it would not be possible to just assume those tiny gadgets would be really doing anything more than making the snake oil salesman rich.

 

[Neuk_]

No you het Billed for KVA but get to use KW. You are paying more for power than what you use. Large power consumers pay extra for Power factor because they effect transmissions systems more than residential users. The effect is massive when you start looking at MW rated motors.

I am not sure why you say no in response to me saying that what @Rickster said is correct? Especially since your following comments support what he said...