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#29105 - 09/08/03 07:59 PM Reversing fans
JCooper Offline
Member
Registered: 12/30/02
Posts: 229
Loc: Kendall Park, NJ USA
Hello all, I have a question about reversing fans, mainly how do they normally work. The fan I was looking at is 110 and the grainger book says that it includes a switch to run the fan in reverse, is this normally done via a low voltage signal cable or by changing windings in the fan motor. I understand that with three phase you can reverse two of the phases to run in reverse but I can't see how to reverse single phase. Thanks in advance.

Jim
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#29106 - 09/08/03 08:12 PM Re: Reversing fans
frank Offline
Member
Registered: 05/29/01
Posts: 373
Loc: windsor ontario canada
Interchange leads 5&8 on the start winding.This will change the north pole position.I know this works on a split phase motor.Ive done it on other types as well but the only diagram ive seen was a split phase on page 347 of the IPT training manual by Herb Putts.Someone will correct me if Im wrong?

[This message has been edited by frank (edited 09-08-2003).]

[This message has been edited by frank (edited 09-08-2003).]
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#29107 - 09/09/03 01:44 PM Re: Reversing fans
JCooper Offline
Member
Registered: 12/30/02
Posts: 229
Loc: Kendall Park, NJ USA
So on a fan with with a remote reversing switch there would be three wires going to it, all with 110 on them?
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#29108 - 09/09/03 02:10 PM Re: Reversing fans
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Going with Franks description

Six + Ground.

Four to run terminals 5 & 8 back and forth from the motor to the switch and two for power.

All the conductors would need to be line voltage.

Bob
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#29109 - 09/10/03 01:08 AM Re: Reversing fans
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8560
Loc: SI,New Zealand
JCooper,
This is a subject that has caused quite a bit of confusion to more than one apprentice, over the years.
It really depends on what sort of motor one is referring to.
Any Split-Phase motor can be reversed by reversing the polarity of either the Start orthe Run winding, but not both.
Shaded-pole motors cannot be reversed and these come in CW (clockwise) and CCW (counter-clockwise) versions.
You can reverse any Cage motor by reversing the polarity of the Phase-Neutral connections at the motor.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
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#29110 - 09/10/03 01:16 AM Re: Reversing fans
Scott35 Offline

Broom Pusher and
Member
Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
Jim,

Check out the drawings for 1 Phase Motors in the Technical Reference section.
(click on the blue "1 Phase Motors" text, or use the link below) http://electrical-contractor.net/ubb/Forum15/HTML/000031.html

This page describes several commonly used 1 Phase Induction Motors.

The first drawing - Fig. 1PM01 - shows the basic reversal connections consept that is typical for the Motors shown on that page.

Sorry we do not have exact terminal numbers to list with the schematics, but the drawings should be very helpful to you anyway.

Scott35
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
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#29111 - 09/11/03 02:58 AM Re: Reversing fans
Pinemarten Offline
Member
Registered: 08/23/03
Posts: 122
Loc: Edmonton, AB, Canada
Most ceiling fans are shaded pole and they can be reversible.
The poles have two shading rings, one on each side of the core. Each has external connections to the switch. When the direction is changed one ring circuit is broken and the other is completed.
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#29112 - 09/11/03 10:28 AM Re: Reversing fans
frank Offline
Member
Registered: 05/29/01
Posts: 373
Loc: windsor ontario canada
I disagree I understand shaded pole motors must be disasembled and flipped to reverse rotaton as Trumpy says it cant be rewired.Bathroom exaust fans are shaded pole and look like a"skullatin motor .Ceiling fans are generaly split phase.Shaded pole motors are clunky loud motors that last forever and are generaly too loud for use in rooms where you would try to sleep or hold a conversation.If i'm wrong someone will correct me and please do always learning here.Also ive only seen copper clips used to shade the pole and other then a bathroom i can only call seeing them in machines like ice makers ect

[This message has been edited by frank (edited 09-11-2003).]

[This message has been edited by frank (edited 09-11-2003).]
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#29113 - 09/12/03 06:18 AM Re: Reversing fans
Pinemarten Offline
Member
Registered: 08/23/03
Posts: 122
Loc: Edmonton, AB, Canada
I may be wrong as well. I have never take one apart.
I was told this in school by a reliable instructor, but he admitted never taking one apart either.
Now that you have me curious, I will go down to the dump with a hammer, find out for myself, and report my findings.
If anyone wants me to mail them the 'remaining evidence' please send postage.
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#29114 - 09/12/03 07:12 AM Re: Reversing fans
SvenNYC Offline
Member
Registered: 08/19/02
Posts: 1685
Loc: New York City
I always thought those cheap little motors found in those reversible window fans from K-Mart had two sets of coils (three speeds intake, three speeds exhaust). No?
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