Variac Inrush advice

[orbiter]

Hi fellas,

Could you advise on where abouts, or in what sort of configuration I can fit an NTC to prevent my 8A variac's inrush tripping the RCD on switch-on please?

I have my variac plugged into the wall via an RCD and I also have an 13A RCD (10A fuse) plug socket on the front of the variac. It's getting to the stage though were I'm getting annoyed with the breaker tripping every few times I switch-on. I seem to be timing the switch-on perfectly in sync with the AC peaks I have various values of NTC going up to 20A.

Any advice appreciated

Thanks guys

[SeanB]

In series with the incoming mains live inside the variac. Use a 8/10A unit in it. If you do not have then use the next higher current one.

[orbiter]

In series with the incoming mains live inside the variac. Use a 8/10A unit in it. If you do not have then use the next higher current one.

Believe it or not my friend I actually thought that was the case, but I just wanted some confirmation first before
shoving 240v through one of these lil' black things

Much appreciated Sean.

Thanks

[SeanB]

Just remember they can run very hot, mount in a space where the heat will not cause a problem.

[orbiter]

Just remember they can run very hot, mount in a space where the heat will not cause a problem.

No problem, I've got it installed now and nothing is touching it etc, also air can move through the area I've fitted it so it should be ok. I will test it as-well though just to make sure everything is safe.

Thanks again

[smashedProton]

If you want to be lazy, you can always have the secondary switch a relay that would short the input over a 10 ohm resistor(series).  I did something like that for a car audio capacitor I have done some time ago.