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15th Feb 2019, 04:04 PM #1Senior Member
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Hercus 260 3phase to single phase motor change
Well its been awhile but im getting my lathe back together now only having trouble with the motor?? I got a single phase motor sourced for the frame size but the front bell housing touches the casting. I got an inverter but the 3pase motor is hard wired Star and from my research they need to be Delta to run an inverter.
Anyone had any luck getting a new motor?happy turning
Patrick
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15th Feb 2019, 04:38 PM #2Mechanical Butcher
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I got a Teco single phase motor for my 260, but the only way I could get it to fit was to remove the cover from the terminal box, and make another with a lower profile.
Something else that might work: As single phase induction motors usually have a big capacitor mounted on the outside of the housing which interferes, move the capacitor to another location to get rid of the big lump.
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15th Feb 2019, 06:28 PM #3Member
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- Newcastle NSW
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I've got a 1959 C model with the original motor and am looking at possibly upgrading to a new motor. Mine has a capacitor mounted on the top and seems to have some sort of solenoid as when i shut it off to make adjustments etc, i sometimes have to wait for some considerable time for the solenoid to "click" before the motor will operate again..... can this motor be serviced or should i also look for a new one? Ideally i'd like to keep the machine as original as possible.
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16th Feb 2019, 08:29 AM #4Member: Blue and white apron brigade
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The motor does not have to be delta, but it does have to be rated for use under 240V 3 Phase.
It just so happens that when a "Y" connected 415V 3P motor is converted to "∆" that it becomes a 240V 3P motor.
Rated for use means it will develop full power and not burn out .
A 415V motor wired at as Y will still run safely under 240V 3P but it will not develop full power.
A 240V 3P motor wired as ∆ will not run safely under 415V as it will over heat under load.
If the motor is hard wired star, a motor rewinder can convert it to ∆ cheaper than you can buy a new motor but maybe not cheaper than you can buy a used motor.
Clear as Mud - don't worry, it took me a while to think this through as well.
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19th Feb 2019, 07:52 PM #5Senior Member
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19th Feb 2019, 09:56 PM #6Member: Blue and white apron brigade
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That's a fairly standard motor used by Hercus on their mills and lathes.
Converting it to ∆ will allow it to run at full power on 240V 3P.
On my Hercus mlll I was able to perform the conversion at the mains junction connector box.
The connector at the red arrow is what is know as the "Star" or common point and has 3 wires attached that go back into the motor.
Normally the start point is buried inside the motor and can be a PIT to get at.
By teasing those 3 wires out and wiring them in a specific order to the existing yellow, brown and red wires this turns the motor into a ∆.
I don't recommend anyone does this themselves unless they are comfortable working with mains power and have have the gear to test the final connections.
A motor rewired will do it for you very quickly and because the motor case does not need to be opened it should not cost too much.
motor.jpg
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20th Feb 2019, 08:32 AM #7Senior Member
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Bob Id buy you a beer if I could really missed reading your stuff!
ill see what I can get done we have a dead motor in the workshop I can pick off another termial blockhappy turning
Patrick
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20th Feb 2019, 11:10 PM #8
I believe that you have a single phase 240V motor on your lathe from the description (external capacitor and a 'solenoid'). The basic configuration for the motor is that there are two different sets of windings, called RUN and START. The RUN winding is energised all of the time that electricity is applied to the motor, and keeps the motor running. However, the motor needs a 'kickstart' to start it in the correct direction and provide additional torque to start a load. This kickstart is provided by a combination of the START winding, the external capacitor, and a centrifugal switch mechanism.
The kickstart system draws much more current than the RUN winding to provide the starting torque needed, and the centrifugal switch disconnects the START winding and capacitor once the motor reaches about 80% of rated speed. When the motor slows almost to a stop, the switch will reconnect the START winding and capacitor, and the motor is ready to start again the next time power is applied to the motor. This switch reconnection generally produces an audible click if the motor is not enclosed in a cast or similar machine base.
From your explanation about having to wait for the 'click' before the motor will restart, I believe that muck, corrosion or extremely burnt switch contacts is slowing the switch release action significantly due to mechanical binding, and hence delaying the reconnection of the START winding and capacitor. A person with a reasonable level of mechanical and electrical ability should be able to remove the drive pulley from the motor, open the end bells of the motor to clean the mechanical and electrical parts of the centrifugal switch. However, if you do not feel confident that you can do this safely, I would suggest that you take the motor to someone with the skills to do the job properly.
In the meantime, I suggest that you do not leave the motor energised while waiting for the click at restarts as this causes excessive current flow in the RUN winding, and may cause them them to overheat and damage their insulation.I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.
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21st Feb 2019, 12:52 PM #9Member
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Thanks malb, i did manage to pull the motor down and clean out the switch etc and it is now up and running as it should. Thanks for your explanation above!
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1st Mar 2019, 11:44 AM #10Senior Member
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Just an update I dropped my motor off at my local shop so we will see what they can do
happy turning
Patrick
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28th Mar 2019, 04:17 PM #11
3 phase and single phase
Hi Guys,
I was given a Squirrel cage single phase motor by a sparky friend when I set my lathe up, works a treat: https://en.wikipedia.org/wiki/Squirrel-cage_rotor
On my hoist 3 HP 3 phase I used a TECO inverter from the States, soft start, speed control and works really well.
It was pretty damn cheap as well.Terry's VFD wiring diagram (finished).pdf
It was was to 110 volts for USA when I got it and it still worked before I noticed and changed it.
I have attached the final wiring PDF (I think) for anyone interested.Terry's VFD wiring diagram (finished).pdf
All the wiring for switches etc. is low voltage for these, very easy.
HOIST VPC.jpg
Cheers
TexTerry's VFD wiring diagram (finished).pdfLast edited by Tex260Z; 28th Mar 2019 at 04:23 PM. Reason: Add photo
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11th Apr 2019, 04:08 PM #12Member
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- Jan 2012
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- Melbourne
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Replacement single phase motor from eBay
I just brought one of these for a 260 that had a missing motor, a drop in replacement.
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11th Apr 2019, 05:29 PM #13Mechanical Butcher
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13th Apr 2019, 11:33 AM #14Member
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13th Apr 2019, 10:21 PM #15Mechanical Butcher
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Good access to terminals and capacitor too, as long as you can get behind the lathe.
Does it have a brand name?
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