I am in an off grid living set up with victron multiplus II 48/5000/70-50 and 15kwh lithium battery. System is great but we have bought a piece of woodwork machinery where the inrush current overloads the inverter. The machine is a planer / thicknesser with a 4kw single phase motor. I have read that motors can draw up to 10 times the nominal current on start up! Am currently looking at options as follows:
1 - fit a ‘soft start’ onto the machine. i am not sure this is possible for the type of motor on the machine and have not had any help from the manufacturers
2 - upgrade to bigger inverter. This is not my preferred option as it runs everything else fine and well within its capacity. Also, a bigger inverter still might not handle the current draw…
3 - use power assist on the inverter in some way so i can utilize my 2kw generator to take up some of the inrush in combination with the inverter. I Could upgrade the genny if this is an option
Hi, you might check siemens for sirius soft starter, I’ve installed these for pump drives up to 500kw, don’t know if they exist for single phase. And, it will cost you
@dazzyk42 you have a few ways to try and resolve this issue. As Ludo mentioned you could go for soft start but you are still close to the capacity of the Inverter. If I had this problem I would get a generator with more capacity. A 2kVA generator is a pretty small unit.
I would go for something like a 5 kVA generator and feed the multiplus with it. Power assist boost factor will be set at 2.0. Set input current limit to about 70% of the generator capacity to start with. 5000 /230 x 0.7 =15 amps.
When the input current reaches 15 amps power assist will kick in providing a maximum of 30 amps. That is about 6.9kVA. If that is not enough try lifting the input current limit. That may cause the generator some problems with shock load but that may be helped with the multiplus dynamic current limit check box ticked.
It would be nice to borrow a generator to ensure this works before committing.
You also have to work with this machine under load. If you want to use the thickness planer sensibly, the multi will probably break down because you don’t have a purely ohmic load but a motor with a capacitor and a cosphi of probably 0.7 - 0.8. In other words, a forced rotating field via a capacitor and not a real three-phase motor.
I think if you could get the motor to start, you wouldn’t be able to work with it.
Thanks for this bit am a bit confused. Are you saying that the multi doesn’t line powering motors? The actual draw of the machine when running is a out 2kw (going up to 3kw periodically) so I thought the multi would cope with this is no other large loads on the system. Are you saying I should really get a bigger inverter? Thanks
Good info thanks - I will try a bigger generator and play about with it. Do you think the generator will be fast enough to respond and help with the inrush current (most of which is in the first second or two)
I’m a bit confused now … I think the machine doesn’t even start? But ok … that’s good.
If a thickness planer draws a lot of current, the Multi will go into overload … Here, of course, a generator coupling would be the best thing to do. The generator would of course be a good solution as a charging backup. It is best to look for an inverter generator, which is accepted by the Multi more quickly than an AVR generator …
I think the machine doesn’t even start? But ok … that’s good. 