440 Volt push-button?

Wot'sitlooklike ? gizaclue

-- Regards,

John Stevenson Nottingham, England.

Tim, Just had a look in the RS book and the Telemechanique range of industrial switches are rated at 10A 500 volt Have you still got that 1930 set of RS books? Nip onto their web site

and type in 318-856 this will get you the green on button assembly complete

319-203 will get the just the switch part with the tech details. If you are not desperate, when you collect that machine from Colin pop round as I have a big box of these switches.

-- Regards,

John Stevenson Nottingham, England.

In the RS cataloge 2, section 10 ( control gear / switches ), the types with snap on blocks like Telemechanique and klockner muller use a 20mm hole, the square d fill a 30.5 mm hole, all three ranges are rated at 500 Vand some of the others are 600v.

Hope this helps

-- Jonathan

Barnes's theorem; for every foolproof device there is a fool greater than the proof.

To reply remove AT

Are the contactor coils 440v? Or do the contactors just switch 440v?

Many thanks John & others. Looking up push button or similar in either the paper or online catalogue didn't bring those up. I don't use them (RS) very often - it obviously helps to know where to look!

Yes they really do operate the 440V contactor coils directly - there's no neutral connection or transformer.

Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Tim,you won`t have more than 250 volts on your pushbuttons as they are only carrying one phase which will only be about 230 volt. regards,Mark.

I have had an email of line from one of the guys telling me that there is no neutral and that these things work direct of 440 volts.Well yes I know that,but you are still switching one phase at 230 volts.If you take a voltmeter of one of the control wires to earth you will only get 230 volts.To get 440 volts you have to connect phase to phase with a resistance(contactor coil} between them.No resistance equals big bang. The way it works is one phase is connected direct to one side of the coil and an other phase is connected through the push buttons to the coil but on each wire there is only 230 volts. Regards,Mark.

Mark,

I don't think that is correct as my J&S 540 is running off a rotary converter with no neutral - so I must assume that the coil is 415v AC phase to phase in series with a normally open holding contact and a normally closed stop button contact - the push button that Tim needs will be in parallel with the holding contact (assuming it's the start button) or in the series chain (if it's the stop button) so will need a 500v rating.

(no no-one has used earth instead of neutral for the coils to work - I checked that when I wired it in!)

Andrew Mawson

Agreed that there will only be around 230V between the contact and earth, but the contacts will be making and breaking (Inductive load, too!) the full 440V (I've just measured it to be absolutely sure). I suppose it all depends which bit of the switch design is the limiting one, but as there does seem to be a properly rated switch readily available, I'll go with that.

Thanks again to all

Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

There's never any harm in using a higher rated switch than you absolutely need in any case - they tend to last longer.

Regards, Tony