mTeryk
Hot Rolled
- Joined
- Jul 4, 2010
- Location
- corvallis,or
I know this has probably been covered before but I've been searching and reading for awhile and am still somewhat confused. Sorry if folks are tired of answering VFD hookup questions but here goes.
The motor on my mill is a 2 speed single voltage (220V) motor. I've installed and run a VFD on a similar motor before and followed the general advise of "just hook it up to the high speed windings". It worked fine for what I needed but have to admit I never ran that mill very hard. This is another mill and I'd like to come to a greater understanding of the compromises in using a VFD for phase conversion. I'm currently running it on a (noisy) rotary phase converter but would like to be able to reverse the motor and eliminate the bulky electrical cabinet.
So here's the motor plate
If I'm reading it correctly I get the following values
RPM-----825------1640
Amps---4.25------6.2
KW------0.90------1.5
PF-------0.80------0.92
It seems a bit strange that it is wired in delta for low speed and Y for high speed as this seems opposite of what I read is the usual. Is that the case?
Using this on-line calculator I get 1.56hp at low speed and 2.62hp at high speed. I believe that the loss of horsepower due to the VFD is linear so I should see 1.31hp at 825rpm with a VFD running at 30hz. If this is correct, I am losing .25hp by using the VFD to slow the motor to 825rpm rather than using a contactor to switch the windings.
Am I understanding this correctly?
My other questions are about the brake data plate. I'm assuming this is a braking resistor that I can hook up to the VFD (eg. an Automation Direct GS2) and get 80 ohms additional of dynamic braking. Is this correct?
Thanks for any help
Teryk
The motor on my mill is a 2 speed single voltage (220V) motor. I've installed and run a VFD on a similar motor before and followed the general advise of "just hook it up to the high speed windings". It worked fine for what I needed but have to admit I never ran that mill very hard. This is another mill and I'd like to come to a greater understanding of the compromises in using a VFD for phase conversion. I'm currently running it on a (noisy) rotary phase converter but would like to be able to reverse the motor and eliminate the bulky electrical cabinet.
So here's the motor plate
If I'm reading it correctly I get the following values
RPM-----825------1640
Amps---4.25------6.2
KW------0.90------1.5
PF-------0.80------0.92
It seems a bit strange that it is wired in delta for low speed and Y for high speed as this seems opposite of what I read is the usual. Is that the case?
Using this on-line calculator I get 1.56hp at low speed and 2.62hp at high speed. I believe that the loss of horsepower due to the VFD is linear so I should see 1.31hp at 825rpm with a VFD running at 30hz. If this is correct, I am losing .25hp by using the VFD to slow the motor to 825rpm rather than using a contactor to switch the windings.
Am I understanding this correctly?
My other questions are about the brake data plate. I'm assuming this is a braking resistor that I can hook up to the VFD (eg. an Automation Direct GS2) and get 80 ohms additional of dynamic braking. Is this correct?
Thanks for any help
Teryk