Motor soft starters and VFD for off grid

That's an excellent idea too.

 

I have a 3phase motor soft start to play with. It's a stellar 30 amp part sr22-30.
Has 3 settings.
Top is ramp up time, 1 to 30 seconds.
Middle is start volts percentage, U%
Bottom is ramp down time 1 to 30 seconds.

Turned on and off with 24vdc signals.

The ramp up time (top) and start volts % (middle) control start up.
The ramp down time (bottom) controls shutoff.

The U% is your starting volts and ramp up time is how fast it goes to full voltage.
So what it's doing on my A/C settings is it's hitting the motor with 30% voltage or about 70v then ramping up to 208v within about 3 seconds.

The way I set it up:
Set the ramp up time near 1 but not on 1, never put it anywhere near 30 unless you're starting something you know is way too big for that motor starter.

Set the middle one to 30%, the lowest setting. Mess with U% probably last.

The bottom one, ramp down time, just leave that at 1 the lowest setting. Ramp down time is the easiest to set, bump up little at a time untill you don't get a voltage surge on shutdown, if you see the amps go up on shutdown the time is turned up too high.
Too much time will make the amps and volts surge on shutdown, too little time will make volts spike. You want to set it so the amps drop off and the volts don't surge.
Usually set between the lowest setting to around the first mark.

Then play with the ramp up time slowly increasing the time. 1/4 to 2/3 of the way up the scale, between a little before the first mark and just past the 3rd hash mark. Smaller motors on low starting torque loads need less time and bigger ones on heavier loads need more time.

Only mess with starting volts, U% if the initial hit of volts doesn't move the motor and load, motors that need a lot of starting torque might not want the lowest setting, but some where between 30% and 60% starting volts should get it moving. I may try out using a varrac to determine minimum start volts.

If turn the ramp up time down to 1 and the %U to 100, which is as close as I can get to no soft start at all, the starting amps will be off my 100 amp scale. Usually I can get the start up amps down to around 50 or so.