Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 13 of 13
-
14th October 2023, 09:34 PM #1
Single phase 240 volt motor running backwards?
I just brought home a Lathe and it has an old compressor motor running a cutter head. It ran in the right hand direction at the sellers house and now at my house its running left hand direction. Why would this be ??
Its single phase 240 volt. And has what looks like two capacitors on it. No switches that I can see. I rang the seller and double checked about switches and its running direction at his house and he confirmed it was running to the right which is the only way it will cut wood with the way the cutters are fitted.
Its in a mess and its plastic cover that holds the capacitors has broken the Tape that was holding it together so be prepared for a shock if you want to see a picture. Its not staying that way and I'm just testing it all out before I do any work with it and the motor, wiring and other parts need work. Ive never seen a single phase motor do this. Does swapping a wire on a single phase motor work like it does on Three phase? Rob.
-
14th October 2023 09:34 PM # ADSGoogle Adsense Advertisement
- Join Date
- Always
- Location
- Advertising world
- Posts
- Many
-
14th October 2023, 10:12 PM #2
Reversing the Active and Neutral on a single phase motor will not make it go in reverse.
You have to reverse either the start winding or the run winding but not both.Those were the droids I was looking for.
https://autoblastgates.com.au
-
14th October 2023, 10:20 PM #3
OK Thanks . Do you have any idea why a motor that ran right is now running left at its new home ? Nothing was touched with wiring or anything .
-
14th October 2023, 10:24 PM #4SENIOR MEMBER
- Join Date
- Oct 2015
- Location
- Ringwood, VIC
- Posts
- 582
Just a guess but if the start cap has failed, it could run happily in either direction with a push start.
If there was stray magnetism or it is slightly unbalanced etc, it could be getting that kick start accidentally.
If it’s safe can you try spinning it the right direction then switch on?
I think that will show if it is the start cap, or the start circuit at least.
-
14th October 2023, 10:35 PM #5
Is the start cap the start capacitor? It had a rough trip home as I knew I would be renewing and probably replacing the motor . So the plastic broken cover became worse and it got a little wet as well.
-
15th October 2023, 05:29 AM #6
Start cap = start capacitor. The reason Russ has given is the only thing I can think of that will reverse a single phase motor. Seeing the photos in the other thread, I think he might be right.
Check the terminals on the capacitors. Make sure they are not wet/covered in crud. Be careful though. They hold a wicked charge and will give you a painful kick if you touch them. I always short them out with a big screwdriver before I poke around in there.Those were the droids I was looking for.
https://autoblastgates.com.au
-
15th October 2023, 09:13 AM #7GOLD MEMBER
- Join Date
- Nov 2007
- Location
- melbourne australia
- Posts
- 2,670
Very odd. Are you absolutely certain it was running in the correct direction at the seller's house? Any chance he just bunged that motor on it to sell it without confirming it ran the right way?
-
15th October 2023, 09:20 AM #8
-
15th October 2023, 09:35 AM #9
Thanks for the warning NC . I am aware of that danger thankfully .That info came to me by reading threads on capacitors in microwave machines. so I look at them and that is all . The motor is all dry now but in a sorry state.
Ive never been game to try and short one out though. I don't trust just the plastic handle on a screw driver. As putting plastic or PVC between me and a charge Like on playing around with cars and motorbike engines spark plugs and just holding the insulated lead has given me a small shock a number of times. Why that happens I have no idea?? Is there a way of being double sure that a charge wouldn't get around a plastic handle to me ? Like standing on a thick block of wood as well ? A rubber mat I suppose is better?
Here's the top of the motor. It was all taped up but rolling it around in the back of the ute positioning it had it all come loose.
It seems to have two capacitors and something joining them that is pointing away in the picture. Two capacitors, that's another thing Ive never seen before on motors. Has that to do with the hard start compressors go through pushing the piston and air ?
IMG_4276a.jpg
Rob .
-
15th October 2023, 09:41 AM #10
Yes Jack I'm certain. He had it cutting wood in front of me and it had to be running to the right to do that. And I rang him and double checked once I saw what was happening here. I thought there may be a chance there was a small reversing switch I hadn't come across in all that mess on top as I wasn't doing any poking around in there as I had been running it . I'm about to load cutter pictures in the thread I put up on the machine here if you want to see machine pictures un related to electrical problems.
F Berry and Sons Sowerby Bridge Yorkshire Lathe
Rob
-
15th October 2023, 09:50 AM #11GOLD MEMBER
- Join Date
- Nov 2007
- Location
- melbourne australia
- Posts
- 2,670
-
15th October 2023, 04:53 PM #12
I couldn’t get the motor to go the right way by spinning first and adding power as it was still spinning. Tried many times and it just spun left.
Problem has been solved by going out to my motor stash and coming in with a 2 HP 3 phase motor that had the same pulley size and two of the mounting holes lined up exactly! And the belt tension was exactly the same as the previous motor! How often does that happen? The motor used to belong to my Wadkin Bursgreen table saw which I upgraded to 3 HP years ago. Now I can do some test cuts. You ever had a mate with a few beers in him telling you off for all the so called “rubbish “ that you were shifting when you moved house. How many hundred did that just save me . Good on the hoarders I say .
IMG_4292.jpg
Rob .
-
15th October 2023, 05:46 PM #13SENIOR MEMBER
- Join Date
- Oct 2015
- Location
- Ringwood, VIC
- Posts
- 582
there are motors with 'start capacitor' and 'run capacitor'.
a picture of the nameplate on the motor may help.
i was wondering if a failed run cap would result in backwards running but i've forgotten the little i knew of the intricacies of those exotic things.
but i think your solution is probably better overall given the state of it and the symptoms.
russ
Similar Threads
-
Replacing A Single Phase Motor With A Three Phase Motor....................
By matthew_g in forum METALWORK FORUMReplies: 26Last Post: 1st May 2015, 04:42 PM -
VFD for 480 Volt single phase
By Kentower in forum METALWORK FORUMReplies: 13Last Post: 27th March 2014, 11:53 PM -
Motor running backwards?
By aussieglen in forum WOODWORK - GENERALReplies: 22Last Post: 28th May 2005, 07:57 PM