By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Dewhurst reversing switch

Connecting a Dewhurst type A switch to my single phase motor

All Topics | Latest Posts

Search for:  in Thread Title in  
Mani Matharu17/12/2019 15:21:16
11 forum posts
12 photos

Hi everybody,

I have a Harrison L5 which I would like to reverse for single point threading purposes. Now I have been looking around on the internet how to do this or better still get my head around what is happening in the motor and the reversing switch, however my electronics skills are not all there. The motor I have is a single phase P.C.M 2.8 HP.

anyway my question if you have not guessed already is how would I go about connecting this. Most diagrams I have seen are for our standard Brooke Crompton model of motor, the terminals on my motor are marked differently U, V and W tags. (See photos) any help will be appreciated.

I will attach images next.

img_0785.jpgimg_0786.jpgimg_0896.jpgimg_0901.jpg

Edited By Mani Matharu on 17/12/2019 15:42:18

john fletcher 117/12/2019 17:47:33
893 forum posts

Hello Mani, first of all take a photo of the motor terminal block as it is now( in motor working mode). Hopefully you have a multi meter or a plain Ohmmeter, better still can you see making on the wires such as U1 & U2 which are the run winding wires. Also Z2, CA4, CA2, SW and CA1 & CA3. Having now got the picture or sketch of the original terminal layout remove the both links and locate U1 & U2. I think the two blue wires are connected to terminal which is CA1 & CA3. A blue wire to each capacitor. John

U1 to Dewhurst terminal 5,

U2 to Dewhirst terminal 7

Z2 to DH terminal 2

CA1& CA3 to DH terminal 6

. 240 volt supply to 1 & 3. Locating U1 & U2 the run winding is important.

Mani Matharu21/12/2019 12:02:03
11 forum posts
12 photos

Hi john many thanks for your reply. The supply live was connected to 1u and the neutral supply to 1v. Sorry John but I do not understand what you mean by the above especially the new markings you have introduced me to fro z2 to ca3. The wires are unmarked coming from windings and caps. Correct me if I am wrong but there seems to be 3 of them (capacitors)? I will upload another picture showing which caps these wires are terminating at. I do have a multimeter


the wires below the terminal block going to the windings are also unmarked. Just got colours brown and black total of 6 wires 2 black and 4 brown.

Mani Matharu21/12/2019 14:47:48
11 forum posts
12 photos

913014e6-de67-4316-bc86-8a41efd66954.jpeg

1519e0e3-259b-44ac-9cce-7f963a5832ef.jpeg

john fletcher 121/12/2019 18:17:12
893 forum posts

Back again Mani. I see your motor is different to the one my friend has,it had just two capacitators and yours has three. All the marking I mentioned came from my friends motor and was attached to each wire.

Leaving all that to one side and looking at the latest picture from you, I think all you have do is move the copper links from the vertical positions to the horizontal positions. I notice both copper links have proper machined slots in them to facilitate easy repositioning. The electric supply still goes to 1u and 1v as before.John

Mani Matharu31/12/2019 11:50:10
11 forum posts
12 photos

So John, I have moved the copper plates to the horizontal position, please do not mind the connections they are not permenant for this exercise. The motor reverses. I have had help from a cousin also which has boosted my confidence in doing this. I need to just work out how to get the reversing switch to do the switching.

see pics below, I have also come across an instruction regarding the Dewhurst switch. Just for convenience of others.

Dewhurst installation instructions

It reverses

Emgee31/12/2019 12:13:16
2610 forum posts
312 photos

Mani, before you finalise the connections best to get a cable gland to fit the threaded entry, supports the cable and will prevent damage on the threads.

Emgee

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate