Wiring a Super 7 with a Tyco Crompton Motor

A friend has rebuilt his Super seven and bought aa Tyco Crompton 1ph motor.

Can someone advise how to wire this in to a Dewhurst reversing switch?

I know that the link needs to be removed but after that ??????

Brian

Your welcome.

Steve.

Edited By Steviegtr on 13/10/2020 17:08:22

I know the motor markings are different but hope that helps you.

Steve.

Here is a copy of the dewhurst data sheet which you might find helpful.

Peter

Thanks Peter. Always good to have another data sheet in my directory.

regards.

Many thanks for the replies; Steve's diagrams help a bit but the terminal markings are not the same. The Dewhurst data sheets are very useful.

Brian

I find the terminal markings very hard to see, and not familiar with a Tyco motor which took over Brook and several other British makes. If you have access to a multi meter then you can locate/decide which pair are the run and which pair are the start windings, then wire the motor a per Steve's diagram.

Remove the two links and using the multi meter on the lowest Ohm range measure the resistance of the lower pair of terminals, then do the same on the upper pair. The run winding pair will have the LOWEST resistance, maybe 4or 5 Ohms, obviously the other pair will be the start winding which has a short time rating. Don't forget the EARTH wire and if the motor is a resilient mounting type, a link between the base and motor body. Let us know how you get on. John .

Many thanks for the explanation John, the terminal markings, from top to bottom on the photos, are;

Z2

R

S

U2

U1

P

The problem is knowing which to connect to the appropriate terminal on the Dewhurst switch? Steve's diagram shows 4 connections (presumably plus earth) to the motor but on this motor there are 6 terminal posts.

It is a resilient mount and there is a connection between the base and motor body.

My friend does not have a multi-meter and I live some 20 miles away so will visit and try to identify the connection as per your instructions.

Many thanks for your help.

Brian

Hello Brian, you are only concerned with those four terminals ( those connected via the two links) which i mentioned, disregard all the others. Connect the 240 volt supply to 1 & 3, Run pair to 5 & 7, start pair to 2 & 6 as shown in Steve's diagram and know doubt in Peter's leaflet. May i suggest your friend get himself a proper motor starter fitted with No -volt release and use it to stop and start the lathe motor, and only use the Dewhurst switches for changing direction of rotation when the motor is switched OFF.. John

Brian

You need to use the No.1 schematic drawing shown on the Dewhurst leaflet.

Emgee

Many thanks to John and Emgee, I think that should enable a fix.

Brian

My friend has wired up the motor as per the instructions from John and Emgee and it works fine in forward... but in reverse the motor just buzzes. Have we wired it up incorrectly of could there be a fault with the Dewhurst?

Any help much appreciated.

Brian

Pleased to report that my friend has wired in a different NVR switch and the lathe runs in both directions. Many thanks to all who tried to help.

Brian

Brian,

What you describe indicates a possible problem with burnt contacts on the Dewhurst Start winding contacts, I reach this conclusion as fitting a NVR switch in the power supply will not have changed any motor to Dewhurst connections.
If there are badly burnt contacts you may be able to clean them but if too badly damaged I believe you may be able to obtain some spares.

Emgee

That has got me intrigued. I’m now wondering how a NVR starter can affect a Dewhurst change-over switch - unless wired in after the Dewhurst.

I too can't see how changing the the NVR switch can effect the problem.

Les.

Duplicate post.

Les.

Edited By Les Jones 1 on 16/10/2020 20:24:40

Thanks Emgee; in fact the Dewhurst is a rebuilt one with new contacts all round. I agree that it's rather weird that it now works. My own thought are that the motor was a bit 'sticky' before but repeated attempts have freed it off. I say this because the motor was a 'new' one, in a manufacturers box and packaging but has never been used before.

As you can tell, I'm clutching at straws to come up with an explanation but what else could it be??

Needless to say, my friend is over the moon and admits that he is unlikely to use reverse but he likes everything to be correct, including a working reverse.

He asked me to pass on his thanks for the help provided by forum members.

Brian

Brian

Let's hope the motor continues to function properly but if the same "buzzing" returns further checks will be needed to confirm where the problem is.

Emgee

if the same "buzzing" returns further checks will be needed

It would likely be the centrifugal switch in the motor not energising the start windings, however not the case if it runs OK one way. That would leave the start windings not connected for the reverse direction, I would expect?