Relays and wiring them in dc circuit

[n1239999]

Hi

Thanks very much for this forum. It has helped me a lot in the past.

I am currnetly studying level 2 C&Q 2330. I am having problem understanding how to wire and connect push button control using relays and its use with the open and closed alarm circuit. The supplay voltage is 6v and the current is 40 mA.

Any help to explain how they work, latching, and connecting them for level 2 C&G porpuse?

Any help much appreciated.

 

[SPECIAL LOCATION]

Hello n123999. Guinness

Welcome to the forumbulator!

I honestly don't know exactly what your course syllabus is asking for....

But basic concepts of relays(and/or contactors) and latching on / off shouldn't be that hard!

Also I don't know how much you understand already..

So I shall assume not much.. Ignore any bits you already know..

and ask again for any bit that I miss off or don't explain clear enough.

1/ A relay is just a switch which is operated by an electric current flowing through a coil of wire.

The coil of wire creates a magnetic field pulling the respective switch contacts open or closed via an armature lever mechanism.

2/ Relays can have just a single switch contact or multiple switch contacts,

also can have combinations of make switches / break switches.

3/ If you get your 6v supply and connect it directly to the coil windings of the relay the relay will operate, As long as the voltage stays there the relay will stay operated.

Now your example talks of Push switches:

I am guessing this is to use a 6v simulation to introduce you to the concept of machinery start and stop control gear?????

maybe wrong no doubt someone will correct me!

So if you have got two push button switches:

1 x Make switch. (normally open contact, closes whilst physically held in)

1 x Break switch. (normally closed contact, opens whilst physically held in)

And if you make up a little circuit:

If you wire from supply to 'Make switch'

then to 'Break switch'

then to relay winding coil

then back to supply.

So long as you have the make switch held in the relay will operate,

but if you let go of the make switch the relay will release.

Now if you have a pair of make contacts on your relay and bring two wires from these contacts, and wire them in parallel with the make switch.

When the make switch is held.

Relay operates.

Relay contacts provide a parallel path to keep the relay held.

when you release the make button the relay keeps itself held "latched" on.

the only way to release the relay would be to remove power OR

press the Break button.

So the make button could be considered a Start / On / Hold button

and the break button could be considered a Stop / Off / Release button.

Other contacts on the relay could be used to switch on a machine or process of some sort...

The above is a simple illustration of a simple relay latching circuit with a

two button on/off arrangement.

An OFF / Stop button is normally used as an emergency stop feature..

ie.

cuts power

relay releases

and wont re-energizes until you re-do the start button!

HTH

Guinness

 

[ProDave]

Why do they confuse you by using 6V?

I can't think of one single instance of 6V relays control circuits used in the real world. Mostly industrial controls are 24V dc, 24V ac, sometimes 110V ac and even less often 230V ac.

So if they want to teach you industrial control circuits, you would think they would use 24v dc or ac.

 

[Doc Hudson]

Could this be the health and safety police at work again, 6v safer for students?

Doc H.

 

[Lurch]

Can;t see how it makes any difference anyway, it still works the same.