VFD, is it possible and what size?

[tarbellb]

Here is the scope:

I moved into a new place that has a 20amp single phase breaker, 12/2 wire running to the garage.

Can I run a VFD on that size circuit, if so what size?

The equipment I am trying to run is a 5hp 3ph motor, possibly a 7.5hp as well. Not at the same time.

Any help would be appreciated.

 

[exmaxima1]

Here is the scope:

I moved into a new place that has a 20amp single phase breaker, 12/2 wire running to the garage.

Can I run a VFD on that size circuit, if so what size?

The equipment I am trying to run is a 5hp 3ph motor, possibly a 7.5hp as well. Not at the same time.

Any help would be appreciated.

A 120v/20a circuit amounts to 2400 watts, which is about 3 hp max. When you factor in the losses in a VFD, you are closer to 2hp max.

 

[Gokart]

I am afraid you might be out of luck. Most Vfd's that input 120V Single Phase are only capable of outputting 1 HP (4.2 Amps) @ 240v Three Phase

You would need a 60 amp 240V circuit out to the garage to power the 7.5 HP motor with a vfd.

 

[larry_g]

No you can't. A single phase 5 hp motor will pull just above 21 amps at 240 volts.

Amps x volts = watts so 21x240= ~5000 watts So your single phase circuit will have to be capable of carrying a 5000w load or more considering losses.

It doesn't matter whether 3 phase or single phase a 5hp motor is going to pull 5000 watts.

lg
no neat sig line

 

[w1im]

You can run a 1HP 3PH motor on a 120V 20A 1PH circuit with a VFD.

I have a Teco VFD that does this. It requires 17.9A input from the 120V line.

 

[wyliesdiesels]

Gonna need a bigger circuit.

Can u run a new feeder?

Is this garage attached or detached?

 

[Norcal]

A 120 volt input VFD is 1 HP max.

 

[tarbellb]

WOW. Thank you guys for the quick, accurate, and non flaming responses!

Electrical is not my strong point, so im happy to have you guys around.

Yeah, its kinda a bummer. I recently moved to a small NorCal town from Denver. Just before finding out I was moving I came across a killer deal on some 3ph equipment ie 12" 5hp Delta/Rockwell TS, 8" Delta/Rockwell Jointer, 20" 7.5hp Delta Planner. All for basically scrap prices.

After finding out I was moving I sold off most my shop, I do mostly metal and wood work and had all 1phase equipment. Now I have the 3ph stuff here in Cali.... with a rental house and detached garage...on a single 20amp breaker.

Im already maxing out my single breaker with my welder that can switch from 120/220v. Was hoping to find a good way to use my 3ph equipment?

I was planning on getting a shop space out here with 3phase but its just not in the cards right now.

 

[PT Doc]

You can get a KB ac drive that will take 240 single phase and convert to 3 phase and have a max output of 3hp. It would likely cost you about $375 for this drive.

 

[wyliesdiesels]

You can get a KB ac drive that will take 240 single phase and convert to 3 phase and have a max output of 3hp. It would likely cost you about $375 for this drive.

He has a 5hp and possibly a 7.5HP....

 

[Norcal]

Once you go over 3 HP, it gets real expensive for VFD's with a desired single phase input, would have to find a 3 phase input drive that the phase loss parameter can be disabled & derate 50%, but the circuit size would have to be sized for the rated input of the drive, the OP would need 10 HP for the 5 HP motor & for the possible 7 1/2 HP, a 15 HP drive, $$$$.

In order to do what the OP desires a MAJOR upgrade of the wiring would be required, a RPC, Rotary Phase Converter, would be less costly then VFD's. (Wiring upgrade still required.)

 

[tarbellb]

I was aware that running this equipment at the house was not likely....

I guess my last question would be:
What about running a 240v 50 or 60 amp breaker from the box? I could rig up a extension cord, then run that to the VFD. I really would only be using this equipment a couple times a week?

Am I still capped at 3hp (via the KB unit?)

I have tapped into boxes for off site jobs before.

 

[CGT80]

I was aware that running this equipment at the house was not likely....

I guess my last question would be:
What about running a 240v 50 or 60 amp breaker from the box? I could rig up a extension cord, then run that to the VFD. I really would only be using this equipment a couple times a week?

Am I still capped at 3hp (via the KB unit?)

I have tapped into boxes for off site jobs before.

Based on his post and the price, I would say yes, you are still limited. The new breaker you are talking about is what he meant about converting 240 single phase to three phase.

After researching on my own and reading many posts on this topic, I don't know of any better way to run a big three phase motor other than a rotary phase converter, and that will have some drawbacks as well.

The VFD is great for small stuff like my baldor grinder, but when you get into 5+hp three phase motors, most people find it best to buy a single phase motor, or use a rotary converter if they have multiple items in 3 phase.

It is too bad that 3 phase is not common for residential. 3 phase tools run on much lower amperage and the wiring can be smaller. This would make wiring easier and help with the cost of using such large wire for single phase machines. Of course, there would be more demand for the equipment and prices might not be as low on the used market, but it would open up options.

 

[tarbellb]

I guess what I was eluding to is:

Whats the most hp I can achieve by running a new 220v breaker to the garage?

Would it be through a VFD or a RPC?

I own a very heavy duty (8 gauge, 40amp, 10000 watts) 50' extension cord. My thoughts are I could run a "temporary" pigtail out of the box that connects to my extension cord, then run that to a VFD or RPC? Besides the issues of how to run it out of the box, what other issues would I have?

Thanks guys.

 

[wyliesdiesels]

I guess what I was eluding to is:

Whats the most hp I can achieve by running a new 220v breaker to the garage?

Would it be through a VFD or a RPC?

I own a very heavy duty (8 gauge, 40amp, 10000v) 50' extension cord. My thoughts are I could run a "temporary" pigtail out of the box that connects to my extension cord, then run that to a VFD or RPC? Besides the issues of how to run it out of the box, what other issues would I have?

Thanks guys.

The first issue u have is youre renting the place. Without written permission from the landlord u shouldnt be doing ANY wiring.

Just how would u hookup your extension cord to the panel? And Im assuming u meant 1000v NOT 10KV.

And extension cords are not to be used for permanent wiring.

 

[tarbellb]

wyliediesels, sorry but you my friend are not contributing at all to this conversation. Please see yourself out.

 

[tarbellb]

And correction, the cord is rated for 10000 watts.

 

[wyliesdiesels]

wyliediesels, sorry but you my friend are not contributing at all to this conversation. Please see yourself out.

U honestly think any of the other electricians on here will help u with that kind of attitude?

 

[yaidunno]

wyliediesels, sorry but you my friend are not contributing at all to this conversation. Please see yourself out.

Haha, this is too good. He brings up valid legal and code related points, you don't want to hear that, and you tell him to leave? Absolutely unreal.

Here's the bottom line, because it seems that you've missed it. You're not running any of the equipment listed on a 120v 20a circuit. The only way its happening is if you run a new service and add a sub panel in the garage. Rigging up a cord is not the proper way to do it. NEC rules and regulations are not in place to make your life difficult. Instead, they are established and enforced for safety and fire prevention. If you chose to rig stuff up with complete disregard for code, it is unlikely that you will receive any further advise.

 

[soj]

wyliediesels, sorry but you my friend are not contributing at all to this conversation. Please see yourself out.

Surely you jest.

 

[simpler=better]

A MEP-003A 10KW diesel generator can run in 3ph mode...maybe that will help you out?

The flywheel in that unit is HUGE, it should have no problem with the surge that a big motor would create.

 

[tarbellb]

The first issue u have is youre renting the place. Without written permission from the landlord u shouldnt be doing ANY wiring.

Just how would u hookup your extension cord to the panel? And Im assuming u meant 1000v NOT 10KV.

And extension cords are not to be used for permanent wiring.

The whole post is condescending and pointing out ways that it can NOT be done and nothing to help with a solution.

I was simply looking for some out of the box thinking on how to safely run more power to the garage. I dont have the luxury of rewiring, because this is in fact a rental and temporary.

 

[yaidunno]

The whole post is condescending and pointing out ways that it can NOT be done and nothing to help with a solution.

I was simply looking for some out of the box thinking on how to safely run more power to the garage. I dont have the luxury of rewiring, because this is in fact a rental and temporary.

Unfortunately, what your looking to do does not comply with the safety aspect. I am presuming that you want to wire this cord you have into your main panel at the house, run it across your lawn/driveway, and power up the equipment in the detached garage?

While it is physically possible to do just that, and even quite easy, it is against many codes.

 

[wyliesdiesels]

The whole post is condescending and pointing out ways that it can NOT be done and nothing to help with a solution.

I was simply looking for some out of the box thinking on how to safely run more power to the garage. I dont have the luxury of rewiring, because this is in fact a rental and temporary.

Sorry but most on here are NOT going to tell u to do something that is against code.

Why not get permission from the landlord to run a new feed out to the garage?