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VFD Help Anyone? Amps and Breaker/Wire Size - Confused

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Forum topic by PatrickIrish posted 04-25-2017 08:27 PM 619 views 0 times favorited 5 replies Add to Favorites Watch
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PatrickIrish

143 posts in 2439 days


04-25-2017 08:27 PM

I picked up an old 5hp 3 phase machine. Plan on using a VFD to power it. The more I read, the more I get confused.

I know so far that:

If the VFD is a SINGLE Phase input only, it’s a hp to hp ratio. Meaning a 5hp single input VFD will power the 5hp 3 phase motor.

I’m confused on amps and my circuit breaker. I plan to use my dryer outlet, it’s a 3 prong 10-30 outlet. I’m not sure if it’s on 30 or 50 amp breaker.

My motor is an old baldor M3613t motor. Nametag says; 12.6-12/6 amps. 3450rpm, 60hz, 208/230/460 volts

Full load EFF = 84% PF = 94%

I don’t know the Full Load Amps of this motor, it’s not listed.

The 5hp VFD I bought is a 4kw unit. The amps the VFD can take was not listed either.

I would like to make a 20ft extension cord from the VFD to the dryer outlet. Can I do this and if so, what gauge wire? What gauge wire from the VFD to the motor?

Thanks in advance


5 replies so far

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PatrickIrish

143 posts in 2439 days


#1 posted 12-17-2017 06:20 AM

Bumping this, hoping for some info.

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MrUnix

7388 posts in 2592 days


#2 posted 12-17-2017 06:39 AM

You can use something like the L510-203 (sensorless vector) or FM50 (V/Hz). It’s rated for up to 10.5A 3-phase output, but can sustain 100% overload for about a minute. Your motor is rated at 12A FLA, which it will never, if ever see. Lots of folks running 5hp machines on those VFD’s without a hitch (for example, see here). A 30A supply circuit is fine.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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PatrickIrish

143 posts in 2439 days


#3 posted 12-17-2017 06:54 AM



You can use something like the L510-203 (sensorless vector) or FM50 (V/Hz). It s rated for up to 10.5A 3-phase output, but can sustain 100% overload for about a minute. Your motor is rated at 12A FLA, which it will never, if ever see. Lots of folks running 5hp machines on those VFD s without a hitch (for example, see here). A 30A supply circuit is fine.

Cheers,
Brad

- MrUnix

Brad, thanks for the info and OWWN link.

Question about wire, would 12/4 soow work on both ends? I think I’ll run the 12/4 on the VFD to motor end in conduit as well. Reading that it helps prevent fm signal.

View TheFridge's profile

TheFridge

10858 posts in 1880 days


#4 posted 12-17-2017 06:55 AM

12.6A on 208v. 12A on 230v. 6A on 480v.

#10s for any wire you install. Dryer should be on a 30A breaker.

That all I got at a glance.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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MrUnix

7388 posts in 2592 days


#5 posted 12-17-2017 07:04 AM

Manual specifies 12AWG supply wiring for the VFD, so you should be good.

Edit: Just re-read your original post… and you said you already purchased the VFD. The info above is for the TECO VFD’s in particular, so probably not accurate for whatever VFD you have. Like the Fridge sez, for 30A, 10AWG is what you need – if it really is pulling 30A. Would have to know what VFD you have to determine.

Another Edit: Theoretically, if your motor is pulling 12A @ 230VAC three phase, then it would require a hair over 20A input for single phase (single phase = 1.73 x triple phase). Even if you use a factor of 2 to account for any inverter loss/overhead, that would still be under 25A required.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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