DOL Switch Wiring

[Clive]

Hi Guys

Can anyone out there help me, I’ve got a DOL Starter Switch which I want to use for my woodwork machine, but at the moment it keeps tripping out.

The switch is for a 3 phase supply 240 volt, I believe they can be wired for a single phase supply which is what I’m trying to do.

The woodwork machine is purely a hobbyist one, the plate on the motor says its 1.5HP, 1.1KW, 240V, 6.9A.

The switch I’m using is Moeller MSE-M240V Made in Germany.

As already said the switch keeps tripping out, ie if the motor is connected to the switch with no load on the motor it runs quite happily but soon as the motor is attached to a piece of machinery such as a table saw the switch trips out, if I wait about 15 seconds I can then switch the saw back on, only for it to trip again.

I’ve been told there is a connection missing on the switch which I need to make as it’s a
3 phase switch and it could be out of balance causing nuisance switching.

From my diagram could someone tell me where I need to connect the wire?

 

[davesparks]

As its drawn it won't work at all as nothing connects to A1 to pull the contactor in.

Yes you do need to balance the current through the overloads, this is normally achieved by looping the L1 output of the starter back to the L2 input, then connect the motor L to the L2 output.

Plus you need to make sure the overload is correctly set for your motor, usually set to the data plate value of running current for a DOL start.

 

[Julie.]

Move the live to the motor from T1 to T2.

Add another connection T1 to L2

It is tripping due to unbalance


Check that once running if you operate any of the 4 interlock switches at the bottom, the motor actually stops, it isn't clear the way it's drawn that this is the case!

 

[davesparks]

Check that once running if you operate any of the 4 interlock switches at the bottom, the motor actually stops, it isn't clear the way it's drawn that this is the case!

I was struggling with that too, but I think they are right.
What puzzles me is that there's no connection to A1 as far as I can see.

 

[Julie.]

I was struggling with that too, but I think they are right.
What puzzles me is that there's no connection to A1 as far as I can see.

Yeah, I assume A1 and 13 are Interconnected, but not very clear, hence missed in the drawing, but as drawn, yup an issue.

Not fully sure about the safety circuit, I sort of think it's right, but think it ought to be checked.

 

[davesparks]

Yeah, I assume A1 and 13 are Interconnected, but not very clear, hence missed in the drawing, but as drawn, yup an issue.

Not fully sure about the safety circuit, I sort of think it's right, but think it ought to be checked.

They are in series with the hold in contact and overload N/C so should work.

But yes every safety device should always be checked regardless.

 

[ipf]

Agree with all you two say. It's pretty common knowledge to use two of the main contacts in series for the live supply but not surprisingly uncommon for non industrial sparks or learners. It wants looking into with the coil connection, as you say.

 

[Clive]

As its drawn it won't work at all as nothing connects to A1 to pull the contactor in.

Yes you do need to balance the current through the overloads, this is normally achieved by looping the L1 output of the starter back to the L2 input, then connect the motor L to the L2 output.

Plus you need to make sure the overload is correctly set for your motor, usually set to the data plate value of running current for a DOL start.

Hello Davesparks

Thank you for your reply, when you say it won’t work at all as nothing is connected to A1 to pull the contactor in, the motor does run as per my diagram but it keeps tripping out once a load is applied.

As far as the overload is concerned, I’ve got it set at the maximum which is 6 amps see my attached picture.

I understand I might be out of luck and need a higher overload rating but I wanted to make sure I’d at least got it wired up correctly first.

Obviously if it’s still tripping after that I assume it’s got to be the overload rating in which case I’ll have to buy another switch but I will go for a single phase one next time.

 

[David Prosser]

There must be something connected to A1 to make it work. Would it be possible for you post a picture of the top half of the contactor.

 

[Clive]

Move the live to the motor from T1 to T2.

Add another connection T1 to L2

It is tripping due to unbalance


Check that once running if you operate any of the 4 interlock switches at the bottom, the motor actually stops, it isn't clear the way it's drawn that this is the case!

Julie

Have a look at the updated diagram, can you confirm that is what you mean, thank you.

[automerge]1585603955[/automerge]

There must be something connected to A1 to make it work. Would it be possible for you post a picture of the top half of the contactor.

Hi Dave

The only diagram of the switch is inside the cover see attachm

ent, but I will take some more pics tomorrow.

 

[Julie.]

Julie

Have a look at the updated diagram, can you confirm that is what you mean, thank you.

View attachment 56772

Yes, all three phases of the overload will now see current

As long as you're not running it under full load continually, then 6A should be ok even though it's a 6.9A flc

 

[ipf]

Looks like you have 4 remote N/O 'start' buttons, closed, in series in your drawing. They should be stop buttons, breaking the circuit on push, if the wiring is correct. The start/stop involves the overload mechanism. That on the cover shows 2 start contacts, one remote, linking 13 and 14 and then on to A1, the link missing on your drawing. Your drawing isn't correct, so, if it operates, it's not wired as you indicate. Various things need addressing. Are those four all stop buttons, for example?

 

[davesparks]

Hello Davesparks

Thank you for your reply, when you say it won’t work at all as nothing is connected to A1 to pull the contactor in, the motor does run as per my diagram but it keeps tripping out once a load is applied.

As far as the overload is concerned, I’ve got it set at the maximum which is 6 amps see my attached picture.

I understand I might be out of luck and need a higher overload rating but I wanted to make sure I’d at least got it wired up correctly first.

Obviously if it’s still tripping after that I assume it’s got to be the overload rating in which case I’ll have to buy another switch but I will go for a single phase one next time.
View attachment 56769

View attachment 56770

The overload is incorrect for that motor, the data plate clearly gives a running current of 6.9A but the overload has a maximum setting of 6A.

I don't think single phase DOL starters exist, you just adapt a three phase one to suit.

 

[David Prosser]

The overload is incorrect for that motor, the data plate clearly gives a running current of 6.9A but the overload has a maximum setting of 6A.

I don't think single phase DOL starters exist, you just adapt a three phase one to suit.

You can buy them ready "adapted" from RS.

RS PRO 2.2 kW Manual 3PST DOL Starter, 240 V, 1 Phase, IP55 | RS Components - https://uk.rs-online.com/web/p/dol-star-delta-starters/9094091/

 

[davesparks]

You can buy them ready "adapted" from RS.

RS PRO 2.2 kW Manual 3PST DOL Starter, 240 V, 1 Phase, IP55 | RS Components - https://uk.rs-online.com/web/p/dol-star-delta-starters/9094091/

I nearly said you can probably buy one with the extra link fitted at an extra cost.