Current sensing switch

SUNRAY said:

I imagine it is much to do with switching speed and arc suppression but this is a guess as the unit I created for the pumps was 4 pole 5A rated contacts wired in parallel and the pumps were something sizable ~3KW ish. It ran for months without problem, however the contacts didn't switch the load but if they did I'm convinced they would have burnt out very quickly.

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There doesn't seem to be much doubt that the word 'contactor' is generally used to refer to a "high spec" relay - but that doesn't help me to understand what (if anything) is the difference (and the differences of 'requirements' per the relevant Standards) between a "high-spec" component described as a "relay" and one with exactly the same spec described as a "contactor".

As you imply, switching high currents to inductive loads is an issue, but I imagine that switching large DC currents is even more demanding. If they can't do what the specification say they can do, then the spec is obviously just 'lying'- but that's equally true of devices with either name.

Perhaps someone knows 'the answer', at least in general terms?

Kind Regards, John

how about something like this, ok it doesnt turn the extract on as you statrt the saw but if the remote is by the saw then click and you can cut.. simples (and rated at 10A)

https://www.ebay.co.uk/itm/BR-Set-o...359946?hash=item5b87805aca:g:Vm0AAOSw0OVgCrrT

Excuse the mess but this was created in an urgent rush with items to hand on site.
The original coil wire was removed and replaced with a few turns of 1mm enamelled wire shown in black arrows.

I Dare say the same thing could be done with contactor.

SUNRAY said:

The original coil wire was removed and replaced with a few turns of 1mm

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Another re-winder.

A few years ago I needed lots of Amps at 12 Volts. Quickest way was to wind new secondaries on this transformer.

bernardgreen said:

Another re-winder.

A few years ago I needed lots of Amps at 12 Volts. Quickest way was to wind new secondaries on this transformer.

Untitled

• bernardgreen
• 11 Jun 2015
• 1

Untitled

• bernardgreen
• 11 Jun 2015
• 1

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and I know just how difficult that was.
I had a 1000V 2A transformer, removed the secondary, measured it, chopped it into 50 pieces then rewound to make it 18V for a PW Marchwood PSU with 20 2N3055's.

I vowed never again, but since then I've rewound 1200, 625 & 300VA toroidals, in each case removing the outer windings to replace/repair the inners

SUNRAY said:

I vowed never again,

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Same here, I broke the vow although never more than a few Watts