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Re: 208V feeding a 240V motor? [Re: homerjones] #178911 06/15/08 09:22 PM
Joined: Apr 2003
Posts: 13
T
ThorahSparky Offline
Junior Member
Originally Posted by homerjones
seems a little strange for it to be 240v three phase that would be delta which is very rare to findive only seen 208/347 hydro can give you 240 three phase but virtually unheard of


My thoughts exactly, maybe its a single phase 240V sander? If it is 3 phase I would go for a boost transformer, or new motor.

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Re: 208V feeding a 240V motor? [Re: ThorahSparky] #178998 06/20/08 01:36 PM
Joined: Jun 2007
Posts: 106
M
mr_electrician Offline OP
Member
Originally Posted by ThorahSparky
Originally Posted by homerjones
seems a little strange for it to be 240v three phase that would be delta which is very rare to findive only seen 208/347 hydro can give you 240 three phase but virtually unheard of


My thoughts exactly, maybe its a single phase 240V sander? If it is 3 phase I would go for a boost transformer, or new motor.


Sorry guys, it is actually a 220V motor 3 phase. It is on a belt sander. I built a new starter for it as it was not CSA approved. It is European. I was getting nuisance tripping on start up so I just increased the value a bit. Seems to work great now.


Never trust an electrician with no eyebrows!!
Re: 208V feeding a 240V motor? [Re: mr_electrician] #179001 06/20/08 02:21 PM
Joined: Sep 2003
Posts: 200
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u2slow Offline
Member
I would take some sample temperature readings during typical/hard use periods.

208V rated motor on a 208V supply has always bugged me - there's no allowance for voltage drop as when you connect 220/230V motors to a 240V supply.

The same windings are getting less voltage and more current... it's going to equate to more heat.

Anyone compared 208-230V rated motor's life expectancy when compared to 208V and 240V supplies?

Re: 208V feeding a 240V motor? [Re: mr_electrician] #179480 07/15/08 07:51 AM
Joined: Dec 2002
Posts: 1,250
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djk Offline
Member
Originally Posted by mr_electrician
Originally Posted by ThorahSparky
Originally Posted by homerjones
seems a little strange for it to be 240v three phase that would be delta which is very rare to findive only seen 208/347 hydro can give you 240 three phase but virtually unheard of


My thoughts exactly, maybe its a single phase 240V sander? If it is 3 phase I would go for a boost transformer, or new motor.


Sorry guys, it is actually a 220V motor 3 phase. It is on a belt sander. I built a new starter for it as it was not CSA approved. It is European. I was getting nuisance tripping on start up so I just increased the value a bit. Seems to work great now.


220V 3-phase would be pretty unusual in Europe.

Normally you would only find equipment designed to operate at either:

230V 50Hz Single Phase
or
400V 50Hz Three Phase

or, in the UK and Ireland for construction site equipment :
110V 50Hz delivered as split-phase i.e. 55V on each leg, this is designed to prevent dangerous electric shock in the event of cable damage, even without relying on GFCIs/RCDs. Such equipment is supplied via a local step-down transformer.

Previously these were :

220 V and 380V in Continental Europe and Ireland
and
240V and 415V in the UK

EU/CENELEC Harmonisation moved Europe to 230V/400V






Last edited by djk; 07/15/08 07:58 AM.
Re: 208V feeding a 240V motor? [Re: homerjones] #181343 10/04/08 03:15 PM
Joined: Mar 2006
Posts: 81
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bigpapa Offline
Member
Usually the motors are 230-460V. Taking the valid points everyone else has said into consideration,there is one other thing to consider.

This motor will underperform to a certain degree because of low voltage but what level of performance do you require? If you need the full horse power from this machine then you will need a 3ph autotransformer and 230V. You won't find an autotransformer for 208 - 240V as readily.

If the machine is more capable than your requirements then you will not overheat anything. A 240V motor will run fine on lower voltage as long as there is a light work load.
You can run a 460V motor on 240V but with very little available torque and no overheating under no load.

If the machine is overkill in size you will probably be ok but watch the startup current. It will also stall easier when you load it up and or trip the O/L relay.

I have a customer that has a large 230V 3ph belt sander for sanding doors and it works acceptable on 204V - 208V but he has to be careful to moderate the rate of feed into the machine. Since it has an automated feed this is not a big deal. Your milage may vary of course. You could always try it on 208V before committing to a transformer purchase.
If the motor is 220V then even better.

Just my opinion.

Last edited by bigpapa; 10/04/08 03:17 PM.
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