Motor controls, DOL starters etc

[TheCodboy]

Hi all. I'm looking to build myself a rig with a small single phase motor and learn a bit more about motor controls etc. I mostly do domestic and some commercial but haven't much experience with motor controls. I always looks at ways to improve myself and my electrical knowledge. Most DOL starters would be pre wired so i take it there wouldn't be much to be gained from that. So would i be better buying NO & NC Switches, Contactor and overload and building it that way? Also looking for advice with regards to contacts 97/98 on the overload. Again, this is not a job or anything like that, this is solely for the purpose of building a rig to give me a better understanding. Any guidance and advice would be very much appreciated. Thanks

 

[westward10]

Sounds like a good idea then you can see the workings and understand the principles of the control. 97 and 98 terminals are NO (Normally Open) until the relay trips which closes them and could be used to provide a visual or audible warning that the relay has operated. Terminals 95 and 96 are NC and incorporated into the control circuit.

 

[TheCodboy]

Sounds like a good idea then you can see the workings and understand the principles of the control. 97 and 98 terminals are NO (Normally Open) until the relay trips which closes them and could be used to provide a visual or audible warning that the relay has operated. Terminals 95 and 96 are NC and incorporated into the control circuit.

Is there anything else you think I would need the make a start??

 

[westward10]

You could buy a DOL starter complete and deconstruct it with separate NO and NC control switches. You could get some red and green indicators and incorporate them into the control circuit, green for good and running and red for relay fail across the 97 and 98 terminals.

 

[TheCodboy]

You could buy a DOL starter complete and deconstruct it with separate NO and NC control switches. You could get some red and green indicators and incorporate them into the control circuit, green for good and running and red for relay fail across the 97 and 98 terminals.

Thanks. I'll start having a look!

 

[westward10]

If you get a starter with a low enough rated relay you can create a trip situation by just running a kettle through it.

 

[TheCodboy]

If you get a starter with a low enough rated relay you can create a trip situation by just running a kettle through it.

So am I right in thinking that with a smaller starter,the control circuit won't need it's own protection where as once you start getting bigger,the control circuit would have its own circuit protection?

 

[pc1966]

So am I right in thinking that with a smaller starter,the control circuit won't need it's own protection where as once you start getting bigger,the control circuit would have its own circuit protection?

Usually you must have fault protection up-stream, so fuse or MCB, but the overload protection for the motor is covered by the (usually adjustable) thermal trip on the starter.

 

[westward10]

So am I right in thinking that with a smaller starter,the control circuit won't need it's own protection where as once you start getting bigger,the control circuit would have its own circuit protection?

Prewired DOL starters generally don't incorporate circuit protection into the control circuit.

 

[TheCodboy]

Prewired DOL starters generally don't incorporate circuit protection into the control circuit.

So that's due to the smaller amount of demand, whereas something drawing more load,the smaller control circuit will have its own protection yes?

 

[westward10]

So that's due to the smaller amount of demand, whereas something drawing more load,the smaller control circuit will have its own protection yes?

It isn't likely to pose a fault issue due to the nature of the wiring and should the coil fail it is such fine wiring it will likely just rupture like a fuse, that is my personal theory by the way?

 

[TheCodboy]

It isn't likely to pose a fault issue due to the nature of the wiring and should the coil fail it is such fine wiring it will likely just rupture like a fuse, that is my personal theory by the way?

So your saying use the control circuit wiring as fuse wire!! ?

 

[westward10]

So your saying use the control circuit wiring as fuse wire!! ?

I was referring to the fine wire of the hold in coil?

 

[TheCodboy]

I was referring to the fine wire of the hold in coil?

??? Suppose that makes more sense!!!

 

[ipf]

Learn about connecting a 3 phase starter controlling a single phase motor
and make sure it's a 230v coil.
You could acquire and connect, for the sake of it, but overloads would be pointless with such a motor. O/L push button to test, I suppose......but live working, remember.