Schneider DOL motor starter switch query

[yourmomm]

Hi. Ive wired single phase 240v motor starter switches before but am confused by this one....

Where the earth binding posts usually are on the side of the switch box, this one has one earth binding post and one neutral. I have no idea why the neutral one is there?! Ive never seen this before... normally its just two earthing posts: one for supply and one for motor.

Can I just wire the stater normally (ie two lives, in from supply and out to motor; earths from supply and motor both to the single earth binding post, and an overload jumper between T3 and L3) and ignore this N binding post completely?

Many thanks



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[NCArcher]

A photo would help. I can't really picture what you are describing.

[yourmomm]

Ok. Here are some photos but not that clear....the necessary wires are not connected (or visible) yet, but:

The supply live goes to L1
The supply neutral goes to L3

The L terminals are white, seen top of switch

The motor live leaves from T1
The motor neutral leaves from T2

The T terminals are hidden from view, underneath switch, in black

There will be an external wire from T3 to L2, to keep all poles populated

You can see the jumper wiring already in place, making necessary connections (eg between L3 and A1; between L1 and 13)
The two halves of the switch have internal jumpers connecting (eg) 14 with 95, A2 with 96.

The earth binding post is top right on the switch casing. The neutral binding post is bottom right. They look silver screws.

Soooooo....since we only have three wires coming in from supply AND going out to motor, (ie live, neutral and earth), and ive already got all the terminals laid out for these wires (L1, L3, T1, T2, and the earth binding post for both supply and motor earths), and all the other jumpers,(external and internal) already seem to be in place, then why the neutral binding post?! And why are the instructions (attached) telling me to attach a neutral wire to this post?! What neutral wire?! I have none left!

Am i meant to run an additional jumper wire from L3/A1 (the neutral feed) to this neutral binding post? If so, is it terminated there, or fed to another terminal? The binding post is not obviously connected to any other terminals, but may be internally....really doesnt look like it though so im wondering how a neutral wire goes nowhere?

Thanks for any help. Im stumped.

[yourmomm]

.....and then theres this pdf circuit diagram (attached), for a different but similar starter, which makes a lot more sense than i do, but STILL doesnt explain the rogue neutral binding post:

[NCArcher]

Active supply to L1
Neutral Supply to L3
Motor Active to T1
Motor Neutral to T2

The bridge wires that are there are all you need. Edit: you do need the bridge from L2 to T3. Just noticed it was missing.
The additional loop terminal is there for convenience as this is basically a 3 phase starter used as a single phase.
If you have a 415V coil on the contactor a neutral is not required so you terminate it at the loop terminal.
You have to thread the single phase motor supply through all three terminals because the thermal overload works on 3 phase current (or it needs to see current in all three phases but doesn't care what direction.)
Are you wiring this at home or work? If at work it should be connected and tested by a qualified electrician. It should be done by a sparky at home as well.

[yourmomm]

Thanks NcArcher! I figured it may be something to do with the three phase configuration, as i know nothing about three phase, and had never seen anything like this before....

One other question. This starter is on the back of the table saw-there is a separate 3 stage switch (0, 1 and START), accessible from the front. You can see I have already wired this switch to the starter:

Red cable to 13 (supply live)
White cable to 14
Black cable to 95

This looks good to me. Look good to you?

And, in answer to your question, I'm very much at home but my home is nowhere near a sparky.... call out fees are prohibitive (half as much again, as I paid for the saw!). I did rewire my house in uk though, so I know how to connect the wires, if someone just tells me where they go every now and then! I appreciate that this is entirely at my own risk....Thanks again for the guidance.

[NCArcher]

Going to need more pictures.
Is it a 3 position switch, with start being spring return?
Wiring into the 95 terminal will not do it. You need to break into the stop wiring so that you have the two normally closed contacts in series. The start contact should be in parallel with the start button on the starter so yes connected to 13 and 14.

[yourmomm]

Ok cant get very clear photos due to limited access to rear of spring return START switch, but here is what there is.

Yes, its a spring return START switch. To give an idea of orientation in the photos, the white cable of the spring return switch corresponds to where 0 position on switch is, red to 1, and black to START position.

So, im not sure how i can proceed if ive got the black to 95 wrong...? How can i put both NC contacts in series, given amount of internal wiring on this magnetic starter?

Many thanks once again.

[NCArcher]

Because of the internal stuff you need to wire it as a second stop button. It will become a master off but that shouldn't matter.
Test the wires coming from the switch with a meter. With the switch in the 0 position you will have open circuits across all wires. With the switch in the 1 position you will have a circuit across two wires. these two wires are the stop circuit. I cant see from the photos but there may be a bridging link between two terminals on the switch. When the switch is turned to START a circuit will be made to the other wire.
Remove the bridge between L1 and 13 on the starter and connect the stop wires from the switch. The start wire can be connected to 14. You will be unable to start the saw from the starter push button unless the switch is in the 1 position but I'm guessing that will not be a problem. The saw can be stopped by either pushing the stop button on the starter or turning the switch to 0

[yourmomm]

Yeah Ok that makes a lot more sense. Will try that and report back. If all else fails, I'll just move the magnetic starter and mount it on the front of the saw.

Hopefully this saw will be (finally) up and running by the end of today, a full month after I bought it....

[yourmomm]

Yep thanks NCArcher-that was it. All sorted and works well, even if I do have to walk to front if the saw every time to turn it on:-

[yourmomm]

Oops. Spoke too soon. Saw WAS working as expected, following NCArchers advice; ran for approximately 1 hour, no problems. Even cut some wood! But I turned it on this morning, and it fired up a bit slowly. Turned it off and on again, and saw struggled to turn, and I heard humming from the magnetic switch. Turned off. Now, nothing, when i turn on: magnetic switch stays in on position, but no saw action at all :( Have checked, and rechecked, all switch connections, which are all fine. Power is definitely going into magnetic switch as indicator light is on. Disconnected three way START switch to only connect and use magnetic switch, and reconnected jumper between L1 and 13; problem still there: power into magnetic switch ok, but no signs of life. Dropped and broke my multimeter in trying to assess situation, so will buy one today and check T1 and T2 for electrical potential, to identify whether the problem is the magnetic switch or the motor (which is brand new, single phase 3hp). Will advise whether electrical potential is seen between T1 and T2 later, but, in mean time, anyone got any ideas of what could be going on here?! Doesnt look good:/

[NCArcher]

I think you'll find that the starter is working ok but you have blown a start capacitor on the motor.

[A Duke]

I think you'll find that the starter is working ok but you have blown a start capacitor on the motor.Hi Tony,
I hope I am wrong but that "0 1 Start" switch could be one of those single phase motor starters in stead of a centrifugal switch.
One of the dangers of diagnosis by remote control.
Yours in the hobby

[NCArcher]

Hi Hugh,
I've never heard of anyone manually switching out the start winding. Pretty risky and a good way to burn out a winding.
Although I have seen stupider things than a manual start. :doh:
I'm certain that the 0-1-Stt cam switch is just someones alternative, start location option. I would have used a couple of buttons but the switch does the job. :shrug:

[yourmomm]

Hi Hugh,
I've never heard of anyone manually switching out the start winding. Pretty risky and a good way to burn out a winding.
Although I have seen stupider things than a manual start. :doh:
I'm certain that the 0-1-Stt cam switch is just someones alternative, start location option. I would have used a couple of buttons but the switch does the job. :shrug:

No I agree. Just looks like a repeater switch location to me.....I'll test when I get home, but, if this is the case, why would the capacitor have blown? Once I replace, how can I prevent from happening again?

[A Duke]

Hi Hugh,
I've never heard of anyone manually switching out the start winding. Pretty risky and a good way to burn out a winding.
Although I have seen stupider things than a manual start. :doh:
I'm certain that the 0-1-Stt cam switch is just someones alternative, start location option. I would have used a couple of buttons but the switch does the job. :shrug:Hi,
Not all that uncommon, I have also come across a toggle type, you switch on and go right over to the start then it spring returns to the centre run position. They are used in corrosive and dusty conditions where the contacts on the auto switches give a lot of problems and as you say a brief power outage = 1 cooked motor if you are not quick enough.
Regards

[A Duke]

No I agree. Just looks like a repeater switch location to me.....I'll test when I get home, but, if this is the case, why would the capacitor have blown? Once I replace, how can I prevent from happening again?Hi,
Because it probably stayed in circuit when it was in run.
Regards

[yourmomm]

Hi,
Because it probably stayed in circuit when it was in run.
Regards

But why would it have done this? This switch stayed at position 1, (and 0 when I turned saw off from there): I never moved it to START at all....

I still cant test as im away from home. Will do so tmw, but im fairly sure the capacitor has gone...just not sure WHY.

If it helps, this saw (and its front mounted 0 1 START switch) used to be single phase, with a (now long-lost) rear mounted single phase starter; at some point, someone converted to three phase, and continued to use the same front mounted switch, wired into 3 phase magnetic starter, which again was rear mounted. As far as i can see, this is common for mbs-300 saws (also referred to as tc-12's by some companies). In fact, I saw someone today with this exact same saw, which was still single phase, and had the same configuration of front mounted 0 1 START switch and rear mounted magnetic starter. There is no manual bypassing of any motor start windings, or any complicated circuits here. The front switch is simply an alternative location START switch.

I bought this saw, sight unseen, from a company who mistakenly sold it to me as a single phase saw. It was only when it was delivered, that I found out they hadnt looked at it properly and that it was three phase! But, in good faith, they supplied a brand new single phase motor and starter switch to convert it. So I am now trying to convert it back to single phase now, and am regretting not just putting the magnetic starter on the front in the first place, bypassing the 0 1 START switch, and avoiding all this hassle-i was trying to avoid making the cabinet look like a piece of cheese with all the holes being drilled in it. Ho hum. Lesson learned. Im going to get me a new start capacitor and start drilling anyway now, but would still like to know why this happened, as its not clear to me-NCArchers advice made sense to me and it all worked exactly as predicted, until this morning, and nothing happened this morning which was any different from all the other times I have turned on the saw in the past few days.

Im wondering whether its possible the motor itself, and/or 0 1 START switch is defective, in which case I can go back to the company that sold me the saw and gave me (separately) the motor, and bill them for the repairs! Obviously cant do this if this was in some way my fault though....

[yourmomm]

Ok all sorted. Meter showed 220v at T1 and T2, so problem was at motor side...but meter also showed capacitor was operating within specs, which confused me...thought this must mean the motor was fried, but tested all wires for continuity, and found one wire between capacitor and motor was only intermittently continuous...pulled apart and found wire had been crushed and strands mostly cut INSIDE the insulation, not at all visible from outside. This being a brand new motor! Poor form from quality control.... Anyhow, replaced cable between capacitor and motor, and all is good again. Thanks all, especially NCArcher, for help:)

[A Duke]

Hi,
Thanks for letting us know what the problem was. These type of problems are a worry when I know I could sort it if I were there. You can more or less judge how much the poster can manage by his questions but the biggest worry to me is the non members who try to solve all things by searching here and are a danger to every one.
Anyway good one :2tsup:
Regards