ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by tortuga - 03/28/24 05:57 PM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
1 members (CoolWill), 23 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
#61784 02/02/06 03:46 PM
Joined: Jan 2006
Posts: 44
M
mshaw Offline OP
Member
Go a call to install an air compressor in a shop that I found has a delta system in it. The compressor is 277/480 but the Delta is 120/240 with a wild leg. Ideas?

#61785 02/02/06 04:21 PM
Joined: Sep 2005
Posts: 153
W
Member
What size is the motor? Does a frequency converter make any sense?

#61786 02/02/06 04:24 PM
Joined: Sep 2003
Posts: 650
W
Member
The motor itself is a three phase load, and doesn't know from wye or delta on the supply. It is _probably_ a dual voltage motor which could be re-connected in the terminal box to operate from a 240V supply. Of of the control/overload/protection hardware would need to be suitably re-configured or upgraded for the increased current and reduced voltage.

-Jon

#61787 02/02/06 04:45 PM
Joined: Apr 2004
Posts: 349
Member
I'm a little confused by something.

Quote
The compressor is 277/480

Assuming the compressor is 3Ø 3W, you don't utilize a neutral so there's really no 277V involved.

Assuming the compressor is 480V 3Ø 3W, and assuming it's not a dual voltage motor (480V 3Ø & 240V 3Ø), then with a 240V delta system I think you're pretty much looking at installing a transformer to match the supply voltage to the compressor.

Radar


There are 10 types of people. Those who know binary, and those who don't.
#61788 02/02/06 04:56 PM
Joined: Sep 2005
Posts: 153
W
Member
In Europe a standard 230 / 400 motor can be star wired to match 3 x 400 and delta wired for the rare 3 x 230 grids.

It will mostly have six terminals and three jumpers to adjust it to local situation.

You do that in a different way?

#61789 02/02/06 06:48 PM
Joined: Sep 2003
Posts: 650
W
Member
Even when a motor is star connected, the neutral of the motor does not get connected to the neutral of the supply.

Common three phase supply voltages in the US are 208V, 240V and 480V, so there you don't find a common situation where you will want to switch a motor between star and delta.

Instead you see motors where there is a factor of two voltage difference between the different possible motor connections, eg 240V or 480V.

-Jon

#61790 02/02/06 07:13 PM
Joined: Sep 2005
Posts: 153
W
Member
@ winnie

mshaw says it is a 277/480 motor. This is nevertheless a typical star / delta ratio. Who knows where it comes from. Only mshaw can tell us whether it's got six terminals.

As a matter of fact I fully agree with you that it might be possible to run the motor delta wired at 240 with a remaining risk that it will burn due to overheating caused by low voltage.

#61791 02/02/06 07:55 PM
Joined: Dec 2000
Posts: 4,294
Member
We need some more info on the compressor.
If it's just a motor and belt driven compressor it most likely has a nine lead motor which can be hooked up as 460 volt or 230 volt.

#61792 02/03/06 07:42 AM
Joined: Aug 2001
Posts: 7,520
P
Member
Quote
Does a frequency converter make any sense?

Frequency converter? [Linked Image]

#61793 02/03/06 08:42 AM
Joined: Sep 2005
Posts: 153
W
Member
We have already installed frequency converters only to adjust local low voltage to motor nominal voltage. This is more a side effect but with small motors easier than a transformer, particularly interesting to run small 3p400V motors on 1p230V.

Page 1 of 2 1 2

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5