Long leads between VFD and motors 6

[GTRgearing]

Application: 300 ft + of cable run between a 460v VFD and a 1/8hp gearmotor. 2 of each gearmotor and drive powering a mobile device. Obviously, motor protection, such as a line reactor is required. But, do they have to be located next to the motor? Are there any new, smaller devices out there? The mobile device is small and real estate is at a premium.

Any suggestions?

 

[sreid]

I would think that you could put the small dv/dt capacitors/damping resistors at the motor and the line inductors at the VFD.

 

[peebee]

1/8hp? I'd consider going 240v instead of 480, then all those problems dissappear. . . .

Voltage drop probably wouldn't even be a problem for a motor that small (might want to double-check that though).

 

[ozmosis]

If you are using un-shielded cable, then 300ft(100M) is usually ok without an output reactor. I would check with the VFD manufacturer and ask them. As peebee says, might be worth going 240v then the peak-peak volts is reduced and, assuming your motor is wound 240-460V (delta-Y), then this motor would have greater protection. Where volt drop is concerned, as your application is driven via a gear motor it is likley constant torque, so ensure your cable diameter is adequate to cope with any potential volt drop otherwise running at slower speeds may not have the torque needed, especially 1/8hp.

 

[DickDV]

peebee has an excellent suggestion, one that I've used for these small motors numerous times with great success. A single transformer take 460V down to 230V to feed both drives will likely weigh less that the two reactors you would need at 460V.

If you decide to use reactors, place them next to the drive. They protect the motor equally well anywhere in the motor leads but, next to the drive, the protect better against ground pulse currents.

 

[aolalde]

I agree with Peebee proposition. Lowering the voltage will improve the motor insulation withstanding spikes. The motor must be reconnected for 230 Volts.

 

[ICEMAN]

Check latter portion of recent thread "Using Explosion Proof Motor on Distorted Supplies" on this site re the issue of VFDs and long cable lengths.

As you will read sinus output filter are better than simple output reactors depending on the type (and carrier frequency) of the inverter.

The explanation is too long to give again here.

Hope it helps.

ICEMAN

 

[peebee]

Sinus output filter? Sounds like a Kleenex! ;-P

 

[steveaz]

Have you considered using a reflected wave trap? I've used the Cutler-Hammer RWT with success in the past.