I hope Gunnar and Muthu are correct. Maybe Tomad will educate us.
I wish to encourage this forum as there may be some real world data coming out that will give us valuable information. The Nema charts are interesting. But Tomads numbers, should they be made available, are greatly anticipated.
I would suggest throttling the valve and allowing the motor to run at 60hz with a lighter load. But burnt is on the right track for a cost saving system.
I have some experience with a pump which the mechanical guys stroked out somehow. (it was a reciprocating pump). The control was calling...
2 Black and 1 Red.
Is it possible there are some Hall sensors or something installed? What manufacturer? For the time being I would isolate these three wires and operate in Wye as the gentelman said.
It may be low input voltage OR low dc bus voltage due to the various issues which have been discussed in this thread. My guess is, if the imput voltage seems to be fairly stable, the DC bus voltage is allowed to dip.
The other possibility is that the motor really is producing something like...
Not necessarily, You are correct. If the motor is delivering 10hp but the current is 36A we have a problem.
I guess what I mean to say is. If the Pump requires a 10hp motor this motor could be operating at (around) 180v RMS and requiring 36A to produce the HP. Or, if the pump is using 15 hp...
Perhaps we can put a wattmeter on the motor? I don't know why I like watt meters but they seem to smooth things out and give a 'real' world number. We can make assumptions based on current and voltage but the wattmeter takes this into accound and removes the power factor issue from the...
Don't put too much stock in the 'harmonics' on the load side. The VFD throws a mess of currents at the motor which, in a scope, resembles a dog's breakfast. The motor itself looks like a big inductor and uses the dog's breakfast to make things spin.
The danger with VFDs, or any power supply...
