One for the electrical experts

[Dougie SwanParticipant @dougieswan43463]

I got this motor and gearbox combo with the hope of fitting it to my mill table

The question is can this motor be reversed?

If it can is it simple?

Thanks

Dougie

[Dougie SwanParticipant @dougieswan43463]

Pic didn’t get uploaded in my last post

[DC31kParticipant @dc31k]

Yes. The motor will have a starting circuit and a running circuit. Reversing it is as simple as swapping live and neutral to one or the other (not both) of these circuits.

See Jim Cox’ books (16 & 24) here: https://www.teepublishing.co.uk/books/workshop-practice-series/

[peak4Participant @peak4]

I think the answer is yes it can, but you’d need to know whether it it capacitor start or run.
It doesn’t seem to be listed, either in the current catalogue, or the 2007 one.

Bill

[Clive Brown 1Participant @clivebrown1]

I’m not certain that it’s an induction motor. The nameplate shows the number 4000, Could this be rpm? The damaged label hides this. If so, it’s probably a brushed motor, reversing might then not be simple. Need more info.

[Clive Brown 1]

On Clive Brown 1 Said:

I’m not certain that it’s an induction motor. The nameplate shows the number 4000, Could this be rpm? The damaged label hides this. If so, it’s probably a brushed motor, reversing might then not be simple. Need more info.

This would appear to be the motor, listed on eBay as still for sale, so I suspect that David may have used a generic photo, as he has a gearbox attached to it, and this one seems to have the same label damage.
SD seems to be the motor frame size, with a wide variety of windings available, so as yet, we don’t have confirmed details of David’s motor
I think the 4000 is rpm, but given that this particular motor probably had a gearbox attached from new, that might be the final output speed, rather than the motor speed

Bill

[Robert Atkinson 2Participant @robertatkinson2]

Typically a Parvralux SD1 motor is a brushed shunt wound motor. A brushed shunt wound motor can be run on AC or DC. The standard product range is low voltage DC but Parvalux make a lot of custom motors. The OP’s motor appears to be marked SD1C. This RS datasheet covers some >200V SD1C motors

https://us.rs-online.com/m/d/d675e1170a12057b268bd1844cf3a5b2.pdf

But the stock numbers are out of date (e.g 266-272). To reverse a brushed motor you must reverse either the field or rotor (brush) connection but not both.
How any wires/terminals does it have? Can you show photos?
If it only has two connections there may not be enough room inside to easily bring out the connections. If it was low voltage it would be less of a worry but there are safety concerns with modifing a mains motor especially a small one.

Robert.

[noel shelleyParticipant @noelshelley55608]

As Has been said is this the motor you have or a picture of a similar type ? Parvalux made many types of motor ONLY when we know which type you have can your question be answered – SAFELY ! Interestingly the motor shown can be used with an old thyristor type dimmer switch to give variable speed ! Noel.

 

[Dougie SwanParticipant @dougieswan43463]

Hi and thanks for the replies

Yes that is a generic pic as the data plate on mine is barely readable

Mine is fitted with a rotary speed controller, I will take more pics later today and post them

Thanks

Dougie

[bernard towersParticipant @bernardtowers37738]

With a rotary speed controller I would think that its brushed.

[peak4Participant @peak4]

From the same catalogue as earlier; scroll through the catalogue and see what gearbox/motor combo you have.

↑↑↑ There used to be another catalogue screenshot there, ↑↑↑
maybe visit Parvalux from the link I provided earlier

Bill

 

[V8EngParticipant @v8eng]

I’m not an expert in anything whatsoever but Parvalux still make motors and are very helpful people generally.

website with contact details at:-

http://www.parvalux.com

[peak4Participant @peak4]

Missing image now formally submitted as a bug report

Bill

[Dougie SwanParticipant @dougieswan43463]

Here are the pics of what I have and the inside of the control box

Thanks again for the replies

Dougie here

[Clive Brown 1Participant @clivebrown1]

From the connection diagram, you appear to have a series wound motor. Exchanging EITHER the white field wires, 3 & 4 OR the red armature wires, 5 & 6 should reverse the motor.

Note, you are dealing with mains voltages. Don’t alter the wires whilst plugged in. The equipment looks somewhat  “used”. Make sure the earth connections, esp. to the motor and controller casings are sound.

[SillyOldDufferModerator @sillyoldduffer]

On the face of it, the motor is reversible using peak3’s third diagram labelled “Series Wound 4 lead Reversing”, which (apart from the speed controller being one way only), is consistent with the second entry “Series Motor 1/4 H.P. (4 leads)” and the wires going into the terminal block.

Visual inspection suggests this is an elderly motor that’s been stored in the damp.  Until proven otherwise, it’s a high-risk safety hazard, – electrocution and fire.  Therefore approach with caution!!!   The advice that follows isn’t foolproof, and assumes a reasonable understanding of electricity, the instruments necessary, and some experience debugging live circuits.  Much easier and safer to do with previous experience, so my advice is not to attempt it if at all uncertain.

I would start by making sure the motor, controller and wiring were all thoroughly dry, perhaps by leaving it for a few days in a warm airing cupboard.

Then check the mains cable for damage.  Ancient insulation perishes, cracks and crumbles so replace the mains lead if at all suspicious.  (What’s visible in the picture looks OK but make sure.)

Strictly speaking the old mains plug is illegal because the L and N pins are solid brass creating a mild risk of a finger touching the live pin whilst the plug is being inserted. Enough children and small fingered adults were zapped to justify a design change.

With a multimeter confirm:

• the fuse in the plug is OK.  (A 3A fuse should be fitted.)
• continuity between the plug’s earth pin and the controller box and the motor.
• no continuity between the plug’s live pin and the controller box and the motor.
• no continuity between the plug’s neutral pin and the controller box and the motor.

Put the motor and controller on a wooden bench, and set the speed control mid-way.  Have a fire blanket or bucket of sand handy.  If the floor is concrete, put down a rubber mat.  (Damp concrete floors multiply the shock hazard.)

Plug the unit into a remote switched off Variac set to zero volts.   Remote means the motor and controller are out of reach if the worst happens during the test.   If any bad happens, unplug the power first, then deal with the emergency.

Power up the Variac, and whilst watching for smoke, sparks, smells or other bad behaviour, gradually increase the power up to 240Vac.  If the controller and motor are working the motor should start spinning at some point as the volts increase.   The variac protects the motor and electronics if there’s a fault.   Don’t touch the device during this test.  (A 60W filament light bulb can be substituted for a Variac, but  requires more expertise.)

If the motor runs OK, after a few minutes, confirm with an electrician’s screwdriver that the motor and controller cases are not live.

Assuming all is well, check turning the speed control knob changes speed.

Let the motor run attended for at least 30 minutes, then disconnect power, and make sure the motor isn’t overheating.

If any of the tests fail, debugging the problem is more difficult.

Comments:

The speed controller looks clean apart from the pre-set pots covered in white efflorescence, which is typical of damp.  They, and the front panel speed control pot, may need a squirt of switch cleaner to get them working, or they may have to be replaced.   Damp is very bad for electronics and there may be corrosion on the other side of the board.   Don’t panic if the electronics are entirely bust, the controller is an inexpensive easily replaced Triac type.

I think a double pole, double throw switch that swaps the armature windings over will reverse the motor.  Ideally. the switch should have an OFF central position because going from forward to reverse whilst the motor is still turning is a common operator mistake, and expensive!

Whether or not the motor is suitable for moving a mill table is moot.   As advertised, the motor spins at 4000 rpm which is far too fast to apply direct to a leadscrew.   My guess is 30 rpm to 100rpm is needed.   The electronic controller is unlikely to provide enough torque at that speed, so gearing down may be required.   Try it and see, but my guess is a 4:1 or 5:1 reduction gear between the motor shaft and the leadscrew will be needed.  I’ve not motorised my mill, so I hope someone who has will comment on the RPM needed and how best to deliver it.  Getting this particular motor to work properly feels like hard work, even if it’s electrically sound.

Dave

 

 

 

 

 

[duncan webster 1Participant @duncanwebster1]

Series wound motor would not be my first choice for a tauble drive, speed will drop as load increases by a lot more than with shunt wound or permanent magnet

[Dougie SwanParticipant @dougieswan43463]

Dave

Thankyou

That was a very informative and useful post for those of us who don’t understand this new fangled Faradays electrictrickery

Seriously it m answered most of my questions

I have already checked the insulation and run the motor without any problems

The speed controller works OK as far as I can tell and your advice about swapping the relevant wires was what I hoped to hear

I have contacted Parvalux for advice and hope to report back with any update

I will change the old plug as suggested and replace the power supply cord

Dougie

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, non-sleeved plugs are not exactly illegal, and you don’t have to change any you have, but! See link below.

https://www.pat-testing-training.net/articles/non-sleeved-plugs.php

Regards Nick.

[Dougie Swan]

On Dougie Swan Said:

…
I have already checked the insulation and run the motor without any problems

The speed controller works OK as far as I can tell and your advice about swapping the relevant wires was what I hoped to hear

…

I will change the old plug as suggested and replace the power supply cord

Dougie

I wouldn’t change the power cord unless it’s damaged, and although the old plug wouldn’t do on a new appliance, the risk to a fat-fingered adult is very low.

Now the motor and controller have proved to be operational and safe, next step is to see if swapping wires will reverse it as described in Clive Brown’s post #710685 above.   Swap the two white wires between terminals 3 and 4 below.

 

Then, with the usual precautions, power up the motor and confirm it now rotates in the opposite direction.   If this works, I’ll describe how to wire a reversing switch.

I doubt Parvalux will be able to help unless you know how much torque is needed to move your mill table.  And even then they will probably simply say the motor isn’t designed for that application.

In practice there’s a good chance the motor will do the job.  But it’s suck it and see rather than calculated engineering.  If the motor can move the table, it’s a runner.   If it doesn’t, time to think again.   Might be wrong, but I think it will need another gearbox.   No harm in trying it without though.

Dave

 

[Robert Atkinson 2Participant @robertatkinson2]

What SOD said except thet the motor appears to have a worm drive gearbox attached so speed at output may be OK.

Just make suur motor body and the meatal box with the controller are properly connected to mains earth.

[Dougie SwanParticipant @dougieswan43463]

Dave

Thanks for your post

I reversed the white wires as you said and the motor did reverse rotation, the speed controller worked front min to max

Thanks

Dougie

[SillyOldDufferModerator @sillyoldduffer]

OK, next step is to wire up a Double Pole Double Throw Switch.

One of these from Amazon should do the job, other suppliers available.  I suggest the 6 pin 2 position version.  You can solder to the terminals or use crimped tags.   If there’s not enough space in the controller box,  a smaller DPDT switch could be used – they’re rated for 3A which is plenty for a 50W motor, if you don’t mind a tiny toggle.

The circuit shows how to wire the switch.  It just swaps the white wires when the switch is thrown.

Always stop the motor before throwing the switch.

Can’t help with the mechanical side except it might help to sacrifice a virgin!

Fingers crossed,

Dave

Dave

[Robert Atkinson 2Participant @robertatkinson2]

SOD said “Strictly speaking the old mains plug is illegal because the L and N pins are solid brass creating a mild risk of a finger touching the live pin whilst the plug is being inserted. Enough children and small fingered adults were zapped to justify a design change.”

Nick noted it is not strictly illegal to non sleeved PIN plugs on existing existing equipment. However SOD’s comment about fingers is not the whole story. It is also about contact with metallic objects. The normal concern is abut things like jewelry chains. A little thought will show that swarf. and off-cuts of wire or sheet metal would be a particular hazard for the typical reader of this forum. If a non-sleeved plug is not fully inserted then a length of swarf can contact a pin or pins. This could result in a shock if you touch the swarf. or a flash and bang if it touches two. The latter could result in a fire or startle the operator of a m achine tool possibly causing a injury from moving or sharp parts. Therfore I suggest that:

ALL “13A” PLUGS IN THE WORKSHOP MUST HAVE SLEEVED PINS

 

Robert.

 

[Michael GilliganParticipant @michaelgilligan61133]

This is purely anecdotal, but I have a recollection that one of reasons for introducing the sleeves was because Arthritis sufferers had been observed using a table-knife to extract a recalcitrant 13A plug from its socket !

The mind boggles … unless and until you have Arthritic hands.

MichaelG.

[Author]

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