Work light on power saw


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Old 04-23-15, 03:47 PM
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Work light on power saw

I have just acquired a new (to me - actually very old) power saw with a 3-phase motor. I will be running it from a VFD fed by a 240V dedicated line.

I want to have a small worklight over it, and want to know if there's any safety / code reason I can't tap 120V off the 220V line to run it. The saw should draw about 12A max, the worklight will be an LED fixture of maybe 10W.

This is the planned wiring diagram....

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Any advise or comments, please?

EDIT - Please disregard the 'attachment' diagram. I can't see how to remove it. The Neutral line does not go into the VFD.

Richard
 
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Old 04-23-15, 04:39 PM
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Why not just use a 240 volt LED lamp? They are readily available on ebay. If you DO use a 120 volt lamp then I would seriously consider adding a small fuse or circuit breaker in the hot lead.

Oh, the incoming voltage is 240, not 220.
 
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Old 04-23-15, 07:15 PM
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Furd has a good idea. Without some information on the 3-phase service, we don't even know if 120 volts would be available. IF 120 volts would be available, you would need a neutral conductor at the saw to get 120 volts.
 
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Old 04-23-15, 08:14 PM
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Joe, he has a regular 240/120 single-phase residential service. He is feeding a variable frequency drive with 240 single-phase and the drive is outputting three-phase. He could easily have a neutral to the junction box at the drive input and then take his 120 volts from the neutral and one leg of the 240. I only mentioned the availability of 240 volt LED bulbs in case he didn't want to have a four-wire supply to the VFD.
 
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Old 04-23-15, 10:07 PM
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Thanks, both of you.

Furd, thanks for suggesting the 240 LED. Since the VFD doesn't need the neutral l can use a three conductor cable if I use a 240V, so that makes things more convenient.

I already ran 4-conductor from the panel to the receptacle, so if I have something down the road that needs a separate neutral and ground I'm set for it.

Richard
 
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Old 04-24-15, 11:51 AM
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Joe, he has a regular 240/120 single-phase residential service. He is feeding a variable frequency drive with 240 single-phase and the drive is outputting three-phase.
I've seen plenty of single phase and 3-phase VFDs, but never have a I seen a VFD with a phase converter built into it. I guess you can learn something new every day.
 
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Old 04-24-15, 01:20 PM
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I've seen plenty of single phase and 3-phase VFDs, but never have a I seen a VFD with a phase converter built into it.
Not at all uncommon with smaller drives, say 7-1/2 horsepower and below. May be some that go as high as 10 horsepower.

Unless I needed the variable speed aspect I would rather reconnect the motor to a 12-lead NEMA standard and then build a capacitor box to run it as a single-phase capacitor start-capacitor run motor. I've done this with several motors with complete success.
 
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Old 04-26-15, 06:21 PM
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I just liked the convenience of the 'plug and play' box, plus the ability to set things like ramp up and ramp down.

This is the unit I bought....

2 2KW 3HP VFD Drive Inverter Low Output Calculous PID Closed Loop Newest Design | eBay

Richard
 
 

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