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🆘 Relay specifically tripping inverter!!! 🆘
bigjoncoop:
!!! A QUICK RECAP TO CONSOLIDATE ALL THE INFO !!!
Situation:
Trying to run a new 8000btu portable air-conditioner off of a inverter.
Main Issue:
If the compressor is connected to the factory on-board relay, the inverter goes into protection when the compressor engages.
If the relay is bypassed and the compressor is wired directly to the mains input, the inverter has no issue at all and compressor run perfectly fine every time...
The battery is way OVERKILL and is supplying plenty of power to the inverter
Things that I've tried:
* Used a different relay
* Tried using 2 different Solid State Relays (1 controlled by DC & one controlled by AC.
* Tried using a 10ohm 25a Ametherm SL32 NTC inrush current limiting thermistor also 2 in series with all above mentioned methods. So after each of those solutions failed, I then connected the NTC's to each one and made no difference.
* Tried using a resistive in rush current limiter consisting of 2- 6ohm 50w power resistors in series for 12ohm connected to a "On Time Delay"
* Also tried using a normal 120v light switch to turn on compressor in order to see if that would still cause the inverter to trip... Still tripped inverter.
I am open to any ideas and I appreciate any help.
Thanks
I also posted a short video the other day before trying a couple recent solutions. If u would like some more details...
https://youtu.be/shoD-iH4Plo
tom66:
I don't think 12 ohms is enough resistance for inrush limiting. Depending on if the inverter is true sine or not, it will be outputting peak voltage of around 170V to create 120V rms. That is a peak current of 14.1A with a dead short load, or 2400W momentary load. Can you try with something closer to 47 ohms? The challenge you will have is having enough resistance to not trip the inverter but enough to get the compressor started. It may be the only option is to buy a different inverter.
I am quite sceptical of brand names you cannot pronounce (may just be a pop-up-and-run kind of Amazon company), and question whether the inverter is capable of its rated power outputs.
Ian.M:
The test with the manual switch proves that the inverter simply doesn't have enough safe overload capacity to handle the motor's starting surge. Why does it work when you hard-wire the compressor and startup the inverter? Well, the inverter has probably got relaxed overload detection during inverter startup, and also it may well start outputting AC before its internal DC bus reaches 170V so reducing the compressor's inrush current. Repeatedly starting it with the compressor direct connected may damage (blow) the inverter.
You can get soft start kits for refrigeration & AC compressors, which specifically limit the starting current surge. You'd need to fit one internally to the AC, between its controller relay and the compressor. The more effective ones aren't cheap and there is no guarantee they'll reduce the current enough for your inverter to be happy.
Psi:
As a quick test you could try wiring 3 of those mechanical relays you have in chain so one triggers the next one etc. to add a few ms delay. They would need to have 2 sets of contacts though, not sure if your relays do?
But you have them shorting out series resistors. So it starts with like a 80R + 40R + 10R in series and ends up directly connected.
80R+40R+10R
First relay shorts 80R
40R+10R
Second relay shorts 40R
10R
Final relay shorts 10R
Now its direct connected
Its not a system i would leave in place, but just as a test to see if it works.
mendip_discovery:
Measure the voltage at the battery. Could you be hitting a low voltage issue with the battery supply just enough for the inverter to go into shut down. The number of times I have had cars do this is annoyingly high.
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