Help with wiring please.......

[slim_boy_fat]

Please bear in mind that I mistrust the magic smoke because I a) can't see it, and b) wouldn't understand it, even if it was as clear as a bell to everyone else.......

I've reached the stage with Maurice where it's time to perform a Dr Frankenstein on him [not yet, Fritz!] and breathe some 'controllable' life into him.

The motor, single phase 240V, has these, which seems straightforward enough, even for a Numpty like me



I have an NVR switch which I'm happy enough with wiring in, and a Dewhurst switch with two banks of four contacts and this is the end of my knowledge/experience. I really need an idiots guide to connecting to wiring, i.e. "connect the brown one to contact X and the blue to contact Y" etc. Please don't link to online wiring diagrams, I've seem those and remain none the wiser. [how did I get this far through life without killing myself.... ?]

I also found this in a drawer but suspect it isn't suitable for my purpose, but confirmation would be appreciated - it has six contacts in total





Over to you for today's challenge.......

 

[rikrobson]

What are the post names/labeled as? there ahould be AZ, A, T, Z



if you want to run off the dewhurst then you need a 4 way cable from the switch to the motor and an earth

usually, you wire the L and N staight through the first and third pairs. the middle pair does the reverse

the one from the L goes to the AZ and the N to the A. The two extra ones go to the T and Z if its going the wrong way swap these at one end.

THe "modern" panel switch box is no good. you'll need a relay with it to do the actual switching.

A and AZ are the Run windings and the T and Z are the Start windings.

 

[slim_boy_fat]

@rikrobson Thanks for that, I'll check the Dewhurst and motor for markings tomorrow and revert.

 

[slim_boy_fat]

@rikrobson OK, checked the motor this morning and found markings



Dewhurst has eight connections in two banks, four on the left and four on the right.

What I need is an idiot's [that'd be me ] guide to cabling, i.e. what colour wire should be connected to which terminal(s). I'm assuming I'll need a length of 4-core cable too, something like this? http://www.ebay.co.uk/itm/351471488990?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Help is appreciated, once I get the cabling sorted I can move on with fitting/adjusting the Tri-Leva setup and should be good to go then. (#fingerscrossed)

 

[rikrobson]

I've just got a new mill (its quite old) that has an old Hoover motor, made in Cambuslang, so that shows its age!! That's wired with a dewhurdt switch (without a cover!!) the cable to the motor is earth,black,blue and brown. the earth is one of the start winding conductors!!!

I've thinking of changing the motor anyway to a 3ph and VFD

 

[rikrobson]

you need 4 core and earth not 3 core and earth

the E is the earth and is basically the case. this should only ever be and earth

The "spare" terminal should probably be the T.

anyway there are 2 coils in the motor. one is the run and should be the black wires and the start will be the yellow. in your case the two coils are joined on the AZ terminal.

you need to take the yellow off the AZ and put it on the Spare terminal. this separates the two coils.

The switch has 4 pairs of termials. you can ignore the last ones, we are only interested in the first 3 pairs.

the top pair will have the live coming in on the left and the right will have the wire for A
the 3rd pair will have the neutral on the left and the right the AZ wire
the middle pair has left to Z and right to the spare one that not has the yellow wire on.
the earth could be also connected to the E on the motor.

This will give you forward and reverse on the Dewhurst. if it goes the wrong way swap the middle pair in the switch

the way its wired currently will do forward only.

the dewhurts basically swaps the current on the Start coil.

 

[slim_boy_fat]

you need 4 core and earth not 3 core and earth

the E is the earth and is basically the case. this should only ever be and earth

The "spare" terminal should probably be the T.

anyway there are 2 coils in the motor. one is the run and should be the black wires and the start will be the yellow. in your case the two coils are joined on the AZ terminal.

you need to take the yellow off the AZ and put it on the Spare terminal. this separates the two coils.

The switch has 4 pairs of termials. you can ignore the last ones, we are only interested in the first 3 pairs.

the top pair will have the live coming in on the left and the right will have the wire for A
the 3rd pair will have the neutral on the left and the right the AZ wire
the middle pair has left to Z and right to the spare one that not has the yellow wire on.
the earth could be also connected to the E on the motor.

This will give you forward and reverse on the Dewhurst. if it goes the wrong way swap the middle pair in the switch

the way its wired currently will do forward only.

the dewhurts basically swaps the current on the run coil.

Brilliant, that's just the concise explanation I needed - I'll print this and take it out to the shed with me. But first to order some of the '5-core' cable to get me organised.

Very grateful for your sharing your knowledge!

EDIT: I'll probably take the opportunity to tidy up the connectors by fitting crimp on ring terminals.

 

[WorkshopChris]

Does the motor definitely have 4 wires out (2 start 2 run) and terminals for a centrifugal switch.
I have come across motors with 3 wires (the two ends of winding's joined internally. Split phase induction.
Hopefully you will find 4.

 

[slim_boy_fat]

Does the motor definitely have 4 wires out (2 start 2 run) and terminals for a centrifugal switch.
I have come across motors with 3 wires (the two ends of winding's joined internally. Split phase induction.
Hopefully you will find 4.

Pic at post #4 shows what I currently have - 'normal' flex to a 13A plug on the other end - this isn't safe, hence the NVR in tandem with the Dewhurst.

 

[rikrobson]

That was meant to say Start coil

I've updated the original post

 

[slim_boy_fat]

@rikrobson Hi again, before I try my luck with the wiring job - I bought this on the 'Bay of Everything http://www.ebay.co.uk/itm/111738998853?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT which only arrived today.

I notice it has a single core and is quite 'strong', is it too heavy duty or will it be OK? For connecting would I be better soldering ring terminals for the motor end or is there a better [i.e. more secure since my soldering isn't gold medal standard ] way of doing it?

Apologies again for the Numpty questions

EDIT: P.S. Noticed that one of the nuts on the motor terminals is missing - do you happen to know what size and thread they are please, I'm not sure if I have anything which looks the same....

 

[rikrobson]

Yup, that wire will be fine. the only issue there may be with single core is if its needs to flex. I presume it wont on your lathe.
if you have a crinp tool and sone crimp on rings, that will do. If you have round nose pliers you could probably make a loop enough to go round a post
As for your missing nut, I'll measure up the post on my DW's motor. I suspect they will be the same.
I have a niggling feeling that they may be BA, but i'll confirm for you.

 

[slim_boy_fat]

Yup, that wire will be fine. the only issue there may be with single core is if its needs to flex. I presume it wont on your lathe.
if you have a crinp tool and sone crimp on rings, that will do. If you have round nose pliers you could probably make a loop enough to go round a post
As for your missing nut, I'll measure up the post on my DW's motor. I suspect they will be the same.
I have a niggling feeling that they may be BA, but i'll confirm for you.

 

[rikrobson]

My motor is 5/32 bsw,which is 32tpi

 

[slim_boy_fat]

Thanks, @rikrobson

 

[slim_boy_fat]

This isn't going well...........

While I'm waiting for the 4-core + earth cable to arrive, I thought I'd jury-rig the Dewhurst to the motor to test functionality.

Followed @rikrobson's script as per post #6 and plugged in and fed power through. Motor ran OK in 'Forward' but tripped the RCD when moved to 'Reverse'. Reset the RCD and no response from the motor in either 'mode'

Then followed a diagram which I found online thus, which shows the AZ and A as different, i.e. reverse - so tried that.

Move D/hurst to 'Forward' and there's a bang and flash from the D/hurst [and a little magic smoke ] and the RCD trips again. reset and try 'Reverse' position same again. Reset RCD again and replaced the fuse in the plug in case that was the cause for the none response. No difference.

Now, no action at all, irrespective of D/hurst position so I'm stumped...... If either now have a fubar'd D/hurst or motor or both?

The next logical move as I see it would be to revert to the motor getting 240V straight from the 13A plug as per pic #1 above to see if it comes to life; if it does I think I'll ignore the Dewhurst unless someone can steer me to getting it to work, and just feed through the NVR which DID work initially.

Could I be trying to reverse a motor which simply isn't designed to do that??

I told you I wasn't to be trusted/let loose with elektrickery............ I'm going to have a coffee before my brain implodes.

Any pointers appreciated

 

[cumbriasteve]

That was the diagram I drew up for Malcolm Myford, works great for me but I am using Cumbrian electric which is a posher type than you have up there

 

[rikrobson]

Did you move the connections on the motor posts?

 

[rikrobson]

Just to make sure you have the two coils separated I'd meter the connections
The motor will run on the run winding only but won't start. You'll need to kick it of answers it will go in either direction. If you get the start building mistake it will do the same but will stop once the centrifugal switch disengages.
If you meter them the run should be less resistance than the start.

How far from perth are you?

 

[rikrobson]

One other option is to get a 3ph mother and vfd.
You'll need to program the vfd and make a control panel but it's not as scary as it sounds.
I'm thinking of doing this on my mill. That will mean I'll have a spare motor that is running off a dewhurst

It's 1/4 hp which should be enough .I'll update you on progress with that project