which switch is which?

while the trigger current is open, I need the switch to stay off. so it would be better if I didn't have to reset manually, and have an always on switch until the trigger AC current is active, then its always off. That would be the most ideal solution.

what are some examples and their manufacturers that people have used?

your query is not clear.Please explain to sugges for a solution.

A Relay will do this, they have both normally open (NO) and normally closed (NC) contacts controlled by the relay coil current.

So if your main circuit is wired through the NC contacts it will work.

When your 'deny signal' sends current through the relay coil....the contacts will open switchig OFF the main circuit.

I totally agree, a RELAY or a CONTACTOR both do more or less the same thing. Easy to wire up as well. I may be wrong but I think Relays are more common in single phase stuff and contactors are available in single and three phase! With a relay you have a seperate base which makes changing faulty units more easy, but the contactor type fit very neatly in consumer boards!

Yes ... I was using relay as a sort of generic term to cover both...so many variants!

But I s'pose one of those DIN Rail contactors is the best?

consider a thyristor

First load will be connected through NC contact of the contactor of which coil will operate on ac source..

The contactor can be energized by a ac power source.Once contactor energized the Current will be denied to Load.The contactor can be made on permanently or momentarily depending on your requirement.If it is made permanent it has to be opened through devices like pushbutton etc.As long as this contactor is ON, current will be permanently denied to the load.

Normally contactors will have NO contacts of higher ratinga SAY UPTO 600 AMPS.

NC contacts will be 10 amps auxiliary.Please inform the load current to give some more inputs if necessary

Relay and contactor are different.

Thank you all for your answers.

I wasn't sure if ac current could be used in relay switching, as I'm new to this circuit designing game. I was off the opinion that a relay switch would alternate in its function of switching, they've obviously solved the method to create a continuous function such as always on or off. Great to know, thanks again. much appreciated

I'll have to look up thyristor, first time I've heard of that.

Now, all I have to do is look at available thyristor and relay switching options and consider the size vrs load handling advantages of the different models. I don't want to be carrying large units, and seeing as I'm only dealing with minute amounts of current, hopefully I can keep the size down too along with the costs.

I just got back from a walk to the local shop, and on my way, I realised that a relay is really a waste of extra circuitry that isn't needed. The current doesn't need to be diverted anywhere, just stalled at the switch. But more importantly, I now know that ac current can be used to create a swtich from always on to always off while the denial current is flowing. plus, a relay is use of extra space, that I want to save.

I've just look up thyristors, nope, thats the wrong function.

anyway, thank you all for your answers.

If anyone know of switch manufacturers with such a simple requirement? please let it be known

YOU NEED A RELAY/CONTACTOR !

That is EXACTLY what they are designed for ...relays come in voltages from 5dc to 230v ac and more.

Forget thyristoes or anything 'clever'

Trust me get a relay/contactor....

The current doesn't need to be diverted anywhere, just stalled at the switch.

!!! This statement is nonsense...The only way you will 'stall' current is by opening a contact (or the active equivalent) or short circuiting it...which would be extremely silly..as you would be blowing fuses every time you operated the trip.

Jeez this is as bad as trying to convince Mrs Cat of something. !

a relay is a diversion process though, and I just thougth its not really needed. but I could use it, there's no denying that. I'd just divert it nowhere or to a nuetral lead.

and the fuse idea works tho, even tho it costs 0.5 c each. but yeah, there are better ways.

a relay is a diversion process though

No No No No No...!

A relay is simply an electrically operated switch.

It may have change over contacts...but you do not have to use every terminal !

If you ask the question please do use the courtesy of listening to the unanimous answer!

I despair..I shall unsubscribe....

you seem stuck on one interpretation only Del!

a relay is a diversion process!! plain and simple.

the term relay is self explanatory. the diagramic/graphical representation is also self explanatory.

how you use it is up to the use of the designer, but its function by DESIGN is to relay current from one place to another.

My approach is that I would rather have a simple switch option if such were available, rather than design with switches where parts of that switch don't serve any purpose. "economy of design"

If I'm unable to find such a simple switch, then I'll just use a relay... its no biggy, just an economy thing.

And another thing!!!

Relays can be very small it depends on the voltage and current you are controlling...

Give us more information if you want the answer s p e l l e d out.!!

1 Amp ac current is the current to be stalled. -otherwise its always on

1amp ac current is the denial current.

are there any relays made to these specifications? or where can I find specifications, so that I may design in a few resistors to match those specifications

and voltage equals 4 in both the denial current and the directed current

How about a simple relay matched to the current used in the circuit that needs to be denied. The relay needs to have a normally closed circuit and have a coil that is designed to work with the ac voltage you have available.

Small, board-mounted relays are available, either NO, NC, or a combination, that can handle signficant voltages and can be configured such that no manual switching is required. I have used one to switch a well pump motor contactor at 230 V. Most electronics suppliers provide a tremendous variety of these devices...

I've seen then in automated units for hydroponics and ventilation control which control 230v or 415v with NO or NC or combos with a physical size of less than 1cm³ with a little orange manual test lever! I can't think of anything more simple or user friendly! I'm totally with you on this one Del! They only cost the price of a Pint aswell!

I agree with Del and the others. Decide whether you need the power to flow through the switch at most times or just momentarily to supply power. If you only need it for a short period of time, use a set of normally open contacts on the relay and energize the coil briefly. If you need constant voltage to be present, use the normally closed contacts and de-activate the power when the coil is energized. Very simple. Most relays are available with several contacts and for different voltages. Type M relays from cutler hammer are even swithable from NC to NO by turning them around after removing and reversing the terminal screws.

good luck

I agree with most of the other posts, but will you not need something to control the contactors, relays etc etc -- such as a PLC control (inputs/outputs) of some sort. Photoeyes to tell the PLC that some condition needs to be met, ie turn switch (contactor, relay etc) on, or turn switch (contactor, relay, etc) off.

Maybe I'm missing something from the original question -- or is someone standing at the machine and turning it on and off at the appropriate time?

nobody needs to watch it if a relay is used, and the diverted current can also be sent to a light indicator to show contact has been made. thanks for that note, I may have neglected to consider that.

Cheers all. thanks

Sir:

For your indicated voltage...amp...an "ice cube" will do verything.

See Mc Master Carr catalog

Mr. Guy.

will do.

thank you.

This thread has been rambling around the issue. Where is the current coming from that is supposed to interrupt the flow of electricity? Is this current momentary or on/off like a switch. Wouldn't it be just as easy to turn off a current flow as it is to turn one on (with a switch)? Are there not double pole double throw switches that have different configurations?

But then, some of the original inquiries do not include the important operating characteristics and/or that really is needed to be achieved. One can easily get off on tangents without these.