Hi all

I am attaching 2 pictures from an electrical drawing. I have a 24v contactor which is being being switched from an output card. The contactor is switching a live and nuetral for a 24v Dc motor. Can anyway explain to me the use of the Nc contact in the drawing? Thanks Kane

 

Yes, it is a braking contact that closes when the contactor drops out, thereby causing the motor to brake when it re-generates slowing down.
Max,

 

Hi Max

Thanks for your reply.

I am starting to understand a little better after your explanation. I am still a little unsure how it brakes the motor?

Cheers
Kane

 

If you try and turn a motor with its terminals not connected it will try to provide a voltage,so by shorting out its terminals it acts as a brake, making it harder to turn thus slowing it down..

 

I am starting to understand a little better after your explanation. I am still a little unsure how it brakes the motor?

Cheers
Kane

You can demonstrate it easily by tuning the (DC) motor by hand and spin the shaft with the leads open and then shorted, you will see the difference in resistance to turning.
Max.