Guru
Joined: 13/10/2014
Location: AustraliaPosts: 1860
| Posted: 04:27am 10 Jan 2023 |
I'm trying get familiar with testing and measuring a running inverter and Toriod, particularly when powering one up in a safe manner to avoid the dreaded splat.
The Ferrite E-core arrived a week ago and it was broken! just paper thin bubble wrap and from a big name AU supplier, sent a picture and waiting for a replacement to arrive. In the meantime I wound 7 turns of the primary lead through the core, left a gap and taped it together.
The inverter for testing is marked 24v, but it should be good to go at 48v, however I had to change a resistor in the over voltage circuit to get the cutoff up to 59 volts. Appears the hi/lo interact and I will now need to change a resistor in the low voltage cutoff, at the moment it's at 44v and the turn on voltage is 51v, need to get them up a bit.
Powering the unit with an adjustable 0-60v 0-4A supply, so cap inrush etc is taken care of. I'm not going to try and remove the 11 caps on this board, 11x 1000uf, only 11000uf.
I placed a 22 ohm 10w resistor in series with the choke to limit current into the toriod and slowly bought the voltage up with the on/off inverter switch on.
Inverter started at 25v and a small lamp on the 220vac side lit up. Secondary waveform looked good on the CRO. Spent some time adjusting and replacing a resistor to get it running at 56vdc. After I was sure it was fine, I shorted the resistor in series with the Choke and left it run for a while.
No Load power is 13.4w (56V @ 240mA)
As I'm limited to around 200watts input at the moment, I decided to plug the Variac into inverter. This Variac has a really Big Heavy toriod and I was vary wary about what this load would do.
Provided the Variac is at Zero, it's fine, flicked the over current on the supply when powered on [expected] and as it's a current limited supply, it holds at 4A and drops the voltage to maintain 4A, however the Inverter ran fine.
I use a Heat Gun set to high and adjusted the Variac up until the 4A current limit led was flickering, left it for a few minutes, waveform still good, however Variac was really noisy if the Load was switched off, but quite with the heat gun on.
Also the inverter waveform was very bumpy on the leading and trailing slopes with no load on the Variac.
I noticed this noise with the main inverter that is powering the shed, although it's noisy with the load as well, Variac is relatively quite on mains. Must look at the waveform some time. There is quite a lot of load on the main inverter so I thought that it may have dampened the Variac noise, but no.
As a result of this initial test, I know what conditions it will startup under, typical current draw during startup, and there is nothing like looking at waveforms yourself.
Another thing that I did notice, they have one temperature sensor on one of the two smaller (separated) heatsinks, that heatsink had a slight warmth to it, whereas the other half and the full heatsink were cold after a few minutes running at 200w?
Have not done the suggested mods to the EGS002 board yet, going to review the circuit to EGS002 board interface and make sure that any changes will work with this inverter as well.
EDIT Must have fluked the temporary choke, broken core and all, without the choke idle current is 1.4A = 78 watts, added a turn and up slightly, took a turn off and now 230mA = 12.8 watts.
Edited 2023-01-10 18:44 by KeepIS