Query on Frequency

It would be foolhardy to install a switch other than the one recommended by the aircraft manufacturer, lest its inadvertent malfunction should cause the aircraft to misbehave while in the air.

Contact the aircraft manufacturer and follow the guidance received.

The 400 Hz power is for the grounded Aircraft in Maintenance Hangar. Will there be any damage to the 50 Hz Change over switch ? will there be problem in the output supply of the change over switch ?

Ah, some new information; the switch is on the ground and not in the aircraft. Good.

Well, the next person to ask is the one supplying the switch.

Just Go Ahead.

The lower the frequency the greater the chance of arcing. And this is what you are worried about. Don't you?

And I don't have to even guess, you are switching off load. Aircraft mfr, have nothing to do with this, and won't even answer you.

At 400Hz, the skin effect that may cause extra heating compared to what occurs at 50Hz is negligible. Most Changeover switch manufacturers do not derate their products. You need to check various catalogues, and once you select a supplier, ask them to commit the suitability of their product for this aircraft duty.

However, PWSlack has given prudent advice, and you will be better off consulting the aircraft companies.

Two questions :

1.Is this an On-load changeover or Off-load?

2. Is this a ground equipment or on board the aircraft ? (i expect it is ground equipment, still, just to confirm)

The Change over is Off -load .

Its for grounded Aircraft in a Maintenance hangar.

According to electrical point of view it will work fine. Your relay switch core is made of high permiability material so negligible eddy current and hysterisis loss. I guess switch=relay

Its manual change over and not relay.

As i said, not a problem, please check out catalogues of ABB, Socomec (France) who are the leaders in this field in India. Since yours is a mission-critical application, go for a company of good repute, and not by cost.

When you switch a load, there is an arc. At 50 Hz the switch is made so that by the time the next polarity inversion occurs, the arc is quenched by the air. High voltage, and super high voltage have a sealed capsule and a quenching gas. This sounds like 120/240 400 hertz aircraft AC.

Check with the switch maker. At 400 hertz, the polarity reversals might come before the arc is quenched and so it can persist linger and might lead to heating?

This is my speculation from first principals. the maker of the 400 hertz 180 Kva converter will know all about it and if military aircraft, the ops manuals will cover it.

The OP did say it is Off-load.

In the switches i worhed with, the existence of more current zeroes in the time which is taken by the moving contact to fully open actually helps in keeping arcing times even lower at 400Hz than at 50Hz.

Yes, I see. For off load use, the frequency might not matter at all.

As for Arc, I refer to the heated plasma, which sustains the arc, and which might not die off with 400 Hz, thus allowing a reverse flow of currents

QUite right of course. However, the current levels at AC23 duty (which is the most onerous for switches) requires M/B tests at 8I_n, which is not so severe as a short-circuit, and the switches, which depend on current-zero breaking (as opposed to MCCBs which are current-limiting and force a current zero), perhaps find it easier to quench the 400Hz arc than the 50Hz one, even if a couple of restrikes do happen.

i must confess that i have not watched the test, since it was done in Europe, but my colleagues told me this.

Surely it is a Ground Station equipment on which you like to replace.

Is it only a mechanical switch or Electromechanical?

If the 1st case then there seems to be no problem.

If the 2nd case will it be powered by 400Hz source or 50/60 Hz source?