I have noticed over the past few months that my electricity bill has gone up significantly since setting up my Kodak Inverter + Pylontech US3000B (x2) setup (no solar).

There seems to be a constant 2.6A draw on my mains when the inverter is running (batteries 100% for a long time and no load ~20W). When I disconnect the inverter's AC input from the grid, the current draw is 0.0A on my DB mains - so it isn't something else (like geyser, oven, etc.) drawing this current. Mains have my whole house connected, inverter is used as a UPS for my office setup.

Does anyone know about this current draw issue? The constant 400W draw surely can't be normal.

This is when everything in my office is off / standby - 20W confirmed by looking at the load on the inverter.

Input is around 233V-235V 50Hz, output is 230V 50Hz.

I am hoping it is just a configuration that someone can help me out with.

Watch Power application Screenshots of configuration attached.

1 hour ago, Kappa said:

There seems to be a constant 2.6A draw on my mains when the inverter is running

That 2.6A could be misleading you. How did you measure it? Or did you calculate current based on a power measurement. 

You refer to 400W. How did you measure it, is there a  power meter in your db box? 

@BritishRacingGreen
I have a CT Coil with 7-seg digits displaying the current draw, frequency and voltage of my mains placed in my DB box.

The inverter backup UPS is the only thing I've changed and my bill has gone up significantly.

Images below show the measurement with the 100% battery inverter connect and disconnected. Minimal load on the inverter.

Edit: It may be worth mentioning that my area fortunately does not get loadshedding but I cycle the batteries every 4 days.

Edited January 12, 20232 yr by Kappa

4 hours ago, Kappa said:

Does anyone know about this current draw issue? The constant 400W draw surely can't be normal.

That will be 400 VA, but far less than 400 W. It's mostly capacitive, which won't register on a power meter. The inverter has a self consumption of about 50 W when inverting, and about 15 W otherwise.

I suspect that something else is responsible for most of the increase in Eskom consumption.

@Coulomb

I realise perhaps I have been wrong assuming PF = 0.7. How would you recommend measuring the real / active power in this case? I have access to a basic DMM and an entry level Keysight scope. I'd like to confirm the reactive power is as large as you suspect it is.

Appreciate the assistance, thank you.

Edited January 12, 20232 yr by Kappa

13 hours ago, Kappa said:

How would you recommend measuring the real / active power in this case?

If you can do it safely, arrange some temporary wiring and use something like this:

Obviously, you'll need one customised for your power details; this one costs AU$20 (about R235). They have a maximum current capacity of some 10 A, so obviously you can't use them permanently or at full load.

With an oscilloscope (digital or otherwise), you'll need one with two channels, and you'll have to do some awkward gymnastics to avoid ground problems and measure current (across a low resistance high power resistor) and voltage safely. Cheaper scopes might not even be rated to read 230 VAC. [ Edit: measure the time between zero crossings to calculate the phase shift. ]

13 hours ago, Kappa said:

to confirm the reactive power is as large as you suspect it is.

Of course, as the load increases, the power factor will improve, as the fixed capacitive current becomes small relative to larger nearly-in-phase load currents. Since most homes would have a strongly lagging power factor due to fridges, pumps, fans, etc. the small leading current from the inverter's filter capacitor will likely slightly improve your home's overall power factor.

Edited January 13, 20232 yr by Coulomb

23 hours ago, Coulomb said:

Obviously, you'll need one customised for your power details; this one costs AU$20 (about R235). They have a maximum current capacity of some 10 A, so obviously you can't use them permanently or at full load.

Thanks, I've gone ahead a purchased a Watt meter which goes to 16A for R340. Image attached.

The power factor hovers around 0.24 with idle load and drops to around 0.16 with no load. So working with this, the inverter constantly draws around 60W-90W when my loads are idle (~20W).

 

Quote

With an oscilloscope (digital or otherwise), you'll need one with two channels, and you'll have to do some awkward gymnastics to avoid ground problems and measure current (across a low resistance high power resistor) and voltage safely. Cheaper scopes might not even be rated to read 230 VAC. [ Edit: measure the time between zero crossings to calculate the phase shift. ]

Do these meters and the electrical meter used by the utility company all just measure phase angle with (I would guess) some zero-crossing detection to get the Power Factor and then multiply that with the apparent power (VA = V RMS and A RMS)? Or would there be some more sophisticated way?

 

42 minutes ago, Kappa said:

Do these meters and the electrical meter used by the utility company all just measure phase angle with (I would guess) some zero-crossing detection to get the Power Factor

I suspect not, because phase angle calculations only work for sine waves, and many household appliances with diode-capacitor power supplies draw highly non-sinusoidal current. It seems to be a legal requirement that meters are totally fair, so they'd have to calculate real power by integrating instantaneous power measurements.

@Coulomb

Thanks, and thank you for your insights to my problem. I'll start investigating what's causing the massive bill increase. I should probably start by getting a proper power meter in the DB lol

Not sure if I need to close this thread?

2 hours ago, Kappa said:

@Coulomb

Thanks, and thank you for your insights to my problem. I'll start investigating what's causing the massive bill increase. I should probably start by getting a proper power meter in the DB lol

Not sure if I need to close this thread?

@Kappa No dont, share your experience and findings with us when you investigate further. 

And keep in touch, i will also keepmy eyes open for cost effective power meter.