Position of interference filter

[Jeff Layman]

Not the usual cutting-edge electronics, I'm afraid.

I have a tumble drier which consistently trips the RCD (UK voltage).
This does not seem to be an uncommon fault, but in this case happened
when the drier had finished its cycle and was cooling down. The RCD
tripped even though the power switch on the drier was off.

The only component which could be responsible was the interference
filter (in this case just capacitors and a resistor). Can anyone explain
why these are fitted /before/ the mains switch on the appliance, and so
are subjected to mains voltage continuously if the plug isn't pulled or
the power switched off at the socket. Why not fit them after the
appliance power switch?

--

Jeff

 

On Monday, 11 November 2019 13:15:21 UTC, Jeff Layman wrote:

Not the usual cutting-edge electronics, I'm afraid.

I have a tumble drier which consistently trips the RCD (UK voltage).
This does not seem to be an uncommon fault, but in this case happened
when the drier had finished its cycle and was cooling down. The RCD
tripped even though the power switch on the drier was off.

The only component which could be responsible was the interference
filter (in this case just capacitors and a resistor). Can anyone explain
why these are fitted /before/ the mains switch on the appliance, and so
are subjected to mains voltage continuously if the plug isn't pulled or
the power switched off at the socket. Why not fit them after the
appliance power switch?

--

Jeff

The filter will be most effective if it is placed as close as possible
to the point where the mains cable enters the enclosure.

Have you check for carbonised mice, insects or even molluscs?

We stored a dishwasher outdoors (under cover) while the kitchen
was being rebuilt. It was re-installed in the kitchen. About
10 minutes after starting it for the first time there was a loud bang
and the 32A circuit breaker tripped (without blowing the 13A fuse in
the plug). The fault, probably caused by a snail or earthworm cleared
and the dishwasher has been fine ever since (7 years).

John

 

[Rick C]

On Monday, November 11, 2019 at 8:38:30 AM UTC-5, jrwal...@gmail.com wrote:

On Monday, 11 November 2019 13:15:21 UTC, Jeff Layman wrote:
Not the usual cutting-edge electronics, I'm afraid.

I have a tumble drier which consistently trips the RCD (UK voltage).
This does not seem to be an uncommon fault, but in this case happened
when the drier had finished its cycle and was cooling down. The RCD
tripped even though the power switch on the drier was off.

The only component which could be responsible was the interference
filter (in this case just capacitors and a resistor). Can anyone explain
why these are fitted /before/ the mains switch on the appliance, and so
are subjected to mains voltage continuously if the plug isn't pulled or
the power switched off at the socket. Why not fit them after the
appliance power switch?

--

Jeff

The filter will be most effective if it is placed as close as possible
to the point where the mains cable enters the enclosure.

Why? Are you thinking this is a filter for radiated emissions? I would expect it to be for conducted emissions. I guess it could be for both. What emissions would a clothes dryer make? Does the motor emit much?

Have you check for carbonised mice, insects or even molluscs?

We stored a dishwasher outdoors (under cover) while the kitchen
was being rebuilt. It was re-installed in the kitchen. About
10 minutes after starting it for the first time there was a loud bang
and the 32A circuit breaker tripped (without blowing the 13A fuse in
the plug). The fault, probably caused by a snail or earthworm cleared
and the dishwasher has been fine ever since (7 years).

I had an extension cord laying outside, but plugged in. Every once in a while the GFCI (how the yanks spell RCD) would trip. It was the very slight moisture condensed in the morning, not even enough to be called dew, conducting t a real earth ground.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

On Mon, 11 Nov 2019 05:38:24 -0800 (PST), jrwalliker@gmail.com wrote:

On Monday, 11 November 2019 13:15:21 UTC, Jeff Layman wrote:
Not the usual cutting-edge electronics, I'm afraid.

I have a tumble drier which consistently trips the RCD (UK voltage).
This does not seem to be an uncommon fault, but in this case happened
when the drier had finished its cycle and was cooling down. The RCD
tripped even though the power switch on the drier was off.

The only component which could be responsible was the interference
filter (in this case just capacitors and a resistor). Can anyone explain
why these are fitted /before/ the mains switch on the appliance, and so
are subjected to mains voltage continuously if the plug isn't pulled or
the power switched off at the socket. Why not fit them after the
appliance power switch?

This continuous mains voltage is a nasty thing in TVs which have at
least the remote control receiver powered all the time to allow
turning on the TV from the remote control. These EMC filter capacitors
have caused a lot of fires in older sets. The standing order from one
manufacturer was to replace the EMC capacitors each time the TV came
in for service for what ever other fault. It was also suggesting
turning off the TV with the mechanical switch or even better, use a
switched extension cord to daily completely switch it off.

The filter will be most effective if it is placed as close as possible
to the point where the mains cable enters the enclosure.

This makes sense if the enclosure is metallic (or at least conductive
plastic), but in a plastic enclosure, what is the point ?

There are IEC (male) device sockets with integrated EMC filter, which
are effective when directly bolted to the metallic enclosure. Some
integrate d units also have an interlocked fuse holder and mechanical
mains switch.

In proper RF construction, each module is within a metallic box and
each DC and baseband lines are connected through real feed-through
capacitors soldered directly to the box.

Have you check for carbonised mice, insects or even molluscs?

We stored a dishwasher outdoors (under cover) while the kitchen
was being rebuilt. It was re-installed in the kitchen. About
10 minutes after starting it for the first time there was a loud bang
and the 32A circuit breaker tripped (without blowing the 13A fuse in
the plug). The fault, probably caused by a snail or earthworm cleared
and the dishwasher has been fine ever since (7 years).

John

 

On Wednesday, 13 November 2019 04:51:37 UTC, upsid...@downunder.com wrote:

The filter will be most effective if it is placed as close as possible
to the point where the mains cable enters the enclosure.

This makes sense if the enclosure is metallic (or at least conductive
plastic), but in a plastic enclosure, what is the point ?

Every tumble drier that I have seen has a steel enclosure.

John