Powerfllex 40 running to motors of different HP

fwagner5 · Oct 17, 2011

I have a 2HP drive but the mechanical designed it with a 1HP motor and a 2HP motor. Normally if they are the same HP, we would just put a reversing contactor and take the jumper off and wire to the motors. Should there be an overload put in place after the contactor for the 1HP motor to protect it, sicne the drive will be set-up for the 2HP motor. Has anyone done something similar to this to view to be sure that I have everything covered since I will not get to test this until I'm out in field. Any help is appreciated.

bce123 · Oct 17, 2011

2+1=3

The Plc Kid · Oct 17, 2011

You can't run 2 different motor sizes on the same drive without changing drive tuning parameters.

If you want to run it in scaler mode and speed control does not have to be that tight then maybe.

If they were the same HP then no problem but I think you willhave major problems witht this IMO

Ken Roach · Oct 17, 2011

Are you running these motors one at a time, or in parallel ?

If they're in parallel you need supplemental motor protection, and it needs to be a motor overload that can deal with the synthetic sine waves from the drive output. Most simple electronic overloads can't do that.

If they're separate, you still might need supplemental motor overload protection. The PowerFlex 40 doesn't have an selectable overload protection feature, though it does have a selectable current limit.

fwagner5 · Oct 17, 2011

Only one motor will be running at a time using a reversing contactor interlock, as long as wired and programmed correctly. I will run the 1hp motor to bring the load in an position and then the 2hp motor to either lift or rotate the load depending on the application. I forgot to mention that once I saw the one reply of adding.

bce123 · Oct 17, 2011

Take a look at the AB 140-c..... for your motor protection. Are you using the power flex 40 line of drives? are these inverter duty motors? what are their duty cycle? two drives would be better for this app.

The Plc Kid · Oct 17, 2011

If the OP is trying to run in any type of vector mode FVC or sensorless it still won't work correctly without changing the drive parms also.

Try to run a 2HP drive with 1 HP parms in vector won't jive.

jdbeal · Oct 17, 2011

At a mile high for altitude compensation (13% derate) and to lower nuisance faults we always run the next HP size up from the motor with PowerFlex 40 drives. We have never had an issue running a smaller motor with the bigger drive. We have nothing but issues running a drive matched to HP when we get new machinery.

Your application just needs to make sure the drive is stopped before you switch motors or you will probably get a lot of faults. You would only really need an overload device for the 1 HP motor because the drive will have to be set up for the 2 HP FLA.

Ken Roach · Oct 17, 2011

Hmm.

As The PLC Kid points out, you can switch the PowerFlex 40 drive to V/Hz mode (Parameter 125) so that the tuning isn't as important as with Sensorless Vector.

Since you're transporting, then rotating or raising a load, you're probably going to want the best torque control performance the drive can give you, which means using Sensorless Vector control mode.

This sort of application is why more sophisticated drives (including, for example, the PowerFlex 70EC) have selectable "User Parameter Sets", so that they can be switched between tuning parameter sets.

In my opinion you're never too far down the road to change to the proper controller; go search for Pierre's recent thread about the man hoist held together with quarter-inch Grade 3 bolts.

bce123 · Oct 17, 2011

but the mechanical designed it

Normally I dont let this guy design my control panels
TWO DRIVES GETS MY VOTE
Best regards, Steve

The Plc Kid · Oct 18, 2011

jdbeal said:
At a mile high for altitude compensation (13% derate) and to lower nuisance faults we always run the next HP size up from the motor with PowerFlex 40 drives. We have never had an issue running a smaller motor with the bigger drive. We have nothing but issues running a drive matched to HP when we get new machinery.

Your application just needs to make sure the drive is stopped before you switch motors or you will probably get a lot of faults. You would only really need an overload device for the 1 HP motor because the drive will have to be set up for the 2 HP FLA.

You are 100% correct about over sizing the drive but there is a limitation. Normally the rule of thumb is 2 to 1.

Example if you have a 5 HP motor then you can use a 10 HP drive or double the size of the motor. If you break this rule of thumb you normally will have speed and torque problems depending on how far past this limit you are. Just a FYI.

The OP's issue is with tuning.His drive model does not support user parameter sets or parms that are changable by I/O. So in anything but Volts/ HZ or Scaler mode he would be running a 1 HP motor on 2 HP parms or the inverse. Either way in any of the available vector modes it would not control correctly.

The Plc Kid · Oct 18, 2011

I agree with bce123 that for simplicity the best thing to do at this point may be to opt for a second drive.

jseavers · Oct 18, 2011

My vote is two drives, Buy the time you purchase overcurrent protection and a reversing contactor to run two motors you can almost buy that second drive.

Powerfllex 40 running to motors of different HP

fwagner5

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fwagner5

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