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M.Joshi · 07:58 PM

Having opened up the appliance, I discovered that there is an X2 0.1µF 275V interference suppression capacitor across the supply which has no load present when the appliance is in idle mode. Hence, the capacitor remains charged when the plug is removed.

I'm sure I have seen resistors across X2 capacitors in-circuit usually in the Mega-Ohm range?

Looking at the Maplin metal film 2W resistors, they can handle 500V.

Quote:

Originally Posted by Arfa Daily

"M.Joshi" wrote in message
...

Hi Arfa,

You are spot-on, I am referring to the capacitor across the
mains/supply (Usually termed X-type).

We have a kitchen appliance (Moulinex - I think) which has a motor and
is connected by a switch which automatically disconnects when you stop
using the machine.

I have found that if the plug is removed, you get a small
electric-shock if you accidently touch the live & neutral pins. I
tested this by plugging the appliance into the mains socket, then
removing the plug and shorting the two pins together. You can see and
hear a small spark!

I am assuming that either the appliance has a faulty resistor connected
across the supply capacitor or they failed to include one at
manufacture?

You might want to just open the thing up and have a look to see if there is
a resistor across the cap, or that it's not a special CR combination in an
encapsulated package, as they sometimes are. I think it likely you will find
that there is no such resistor present, and the manufacturers felt it safe
for it to be like that. It will have undergone stringent safety tests at the
design and prototyping stages, and will have had to have shown compliance
for safety regulations to have gained its CE approval. Moulinex may well
self-certify of course, but it is more than they would dare do to 'fudge'
this.

If there is no resistor present, I wouldn't advocate adding one, because as
another poster has suggested, this would quite possibly compromise things
like fire safety. Bear in mind also, that any resistor across the mains, has
got to be capable of withstanding at least the peak value of the UK mains,
which is up around 360v worst case, so would realistically want to be rated
to withstand 500v.

What you are encountering is by no means uncommon with this sort of
equipment, but does seem to be 'normal'. I would guess that the amount of
energy stored in the relatively small value of the cap, is probably
considered harmless.

Arfa