Drill tripping earth leakage protector

[Glenn Pure]

I occasionally visit an friend to use his drill press. He has been
having trouble with it for the last year or so as it has been tripping
his earth leakage protector in the fuse box. It only seems to do this
about 5% of the time, and only ever when turning the drill on (not
while it's running). The circuit breaker never trips.

I have pulled sections of the drill apart and fixed a few suspect bits
of wiring that may have been causing connection between active and
earth but the problem still persists.

The motor has a starter capacitor and this was the latest area where I
fixed some suspect wiring (by re-insulating it).

However, problem still exists.

Is it possible that when switching the drill on, the current and
voltage phasing during the in rush could be such that it is confusing
the earth leakage device (with I think is just a current comparator
between active and neutral?).

Any help in where to look to pinpoint the problem would be
appreciated. Is replacing the capacitor likely to help?

Cheers
Glenn
Glenn Pure
Canberra, Australia
Web page: http://www.evans-pure.net

 

[Phil Allison]

"Glenn Pure"

I occasionally visit an friend to use his drill press. He has been
having trouble with it for the last year or so as it has been tripping
his earth leakage protector in the fuse box. It only seems to do this
about 5% of the time, and only ever when turning the drill on (not
while it's running). The circuit breaker never trips.

I have pulled sections of the drill apart and fixed a few suspect bits
of wiring that may have been causing connection between active and
earth but the problem still persists.

The motor has a starter capacitor and this was the latest area where I
fixed some suspect wiring (by re-insulating it).

However, problem still exists.

Is it possible that when switching the drill on, the current and
voltage phasing during the in rush could be such that it is confusing
the earth leakage device (with I think is just a current comparator
between active and neutral?).

Any help in where to look to pinpoint the problem would be
appreciated. Is replacing the capacitor likely to help?

** Fit a 0.1 uF 250 volt AC rated suppression cap across the switch -
bursts of radiated RF energy can trip an ELCB.

Also consider replacing the switch as it may have burnt contacts causing
the arcing.




................ Phil

 

[quietguy]

While it may be completly irrelevent to your problem, it may be of
interest that when an electrician was installing an earth leakage breaker
in my home, he mentioned that many fridges will trip the breaker even
though they are not faulty, and that I should install a non-protected
outlet for the fridge. I did.

David

 

[Jim Gregory]

Glenn
Have you tried using a different RCD or ELCB?
What Wattage/HP?
Has the drill got a built-in electronic varispeed control? If so, there may
be unwanted leakage to Earth there.
Regarding Phil's suggested 250VAC 100nf cap, it could have a 100r 1/2W
resistor put in series with it.

 

[David]

While it may be completly irrelevent to your problem, it may be of
interest that when an electrician was installing an earth leakage breaker
in my home, he mentioned that many fridges will trip the breaker even
though they are not faulty, and that I should install a non-protected
outlet for the fridge. I did.

David

This is not legal any longer. While allowed under the older wiring rules,
the current AS3000:2000 do not make an exemption for RCD protection on
fridges.

David

 

[FruitLoop]

Glenn
Have you tried using a different RCD or ELCB?
What Wattage/HP?
Has the drill got a built-in electronic varispeed control? If so, there may
be unwanted leakage to Earth there.
Regarding Phil's suggested 250VAC 100nf cap, it could have a 100r 1/2W
resistor put in series with it.

Also, What is the actual insulation resistance of the windings .You need a
500 Volt Meggar or equivilent for this test .
Maybe the insulation resistance is a little low , due to infrequent use or
possible minor damage .

You need to do this first to acertain the actual resistance to earth to see
if its a problem before the switch mod .

 

[Glenn Pure]

Also, What is the actual insulation resistance of the windings .You need a
500 Volt Meggar or equivilent for this test .
Maybe the insulation resistance is a little low , due to infrequent use or
possible minor damage .

You need to do this first to acertain the actual resistance to earth to see
if its a problem before the switch mod .

Thanks for various suggestions. I don't have access to a megger so
won't be able to check. The drill is fairly old single speed so it may
have some insulation breakdown. If so, would this typically only
manifest at switch on?

The switch mod sounds simple and inexpensive so may be worth a try
anyway. The switch was replaced recently so unlikely that faulty
switch is the cause.

Cheers
Glenn
Glenn Pure
Canberra, Australia
Web page: http://www.evans-pure.net

 

[Jim Gregory]

GP
If the insulation is breaking down, and it's getting old, I think you may
deserve a new varispeed /2-speed drill (with reverse rotation, if poss) with
a good-sized 15+mm chuck.
Assuming the stand's adjustable grip will accommodate the new collar, of
course.
At least 500W for a bench-press drill. A "hammer" facility may be standard,
I believe they are inexpensive nowadays.

 

[Mike Harding]

Also, What is the actual insulation resistance of the windings .You need a
500 Volt Meggar or equivilent for this test .
Maybe the insulation resistance is a little low , due to infrequent use or
possible minor damage .

You need to do this first to acertain the actual resistance to earth to see
if its a problem before the switch mod .

Phil is, most likely, quite correct. I have a double insulated
vacuum cleaner which does not even have an earth pin
on the 240V plug and I can reliably trip the ELCB by
switching it on and off a few times.

Mike Harding

 

[John_H]

Phil is, most likely, quite correct. I have a double insulated
vacuum cleaner which does not even have an earth pin
on the 240V plug and I can reliably trip the ELCB by
switching it on and off a few times.

Or, it might be time to have your wiring checked!... Snipping the
earth pin usually fixes those sort of problems.

 

[FruitLoop]

Phil is, most likely, quite correct. I have a double insulated
vacuum cleaner which does not even have an earth pin
on the 240V plug and I can reliably trip the ELCB by
switching it on and off a few times.

Whats the brand and tripping current of the core balance unit ?

Im not sure but I suspect 20 ma is the most common on switchboards

The problem is the better the core balance unit , the smaller the tripping
current.This gives better people protection , however nuisance tripping can
occur and thats the balance .

I suppose the other argument could be to have a larger tripping , current
core balance unit , but you need to find out from an electrician what is the
maximum allowed under law .Also would cost too much unless the workshop has
some legacy power tools around that may intermittantly trip the protection
devices .

 

[Mike Harding]

Whats the brand and tripping current of the core balance unit ?

Merlin Gerin - 30mA, but you'll find that will be the maximum
current it is supposed to trip at - the minimum from unit to unit
may be less.

The problem is the better the core balance unit , the smaller the tripping
current.This gives better people protection , however nuisance tripping can
occur and thats the balance .

Of course and therefore one would expect it to trip at random
times, perhaps more often on very damp days for example
but it doesn't - however I can always make my vacuum cleaner
trip it.

Mike Harding

 

[Mike Harding]

Or, it might be time to have your wiring checked!...

I'm an electronics engineer - I _know_ how to check
wiring.

Snipping the
earth pin usually fixes those sort of problems.

As I said: the vacuum cleaner doesn't have an earth pin.

Mike Harding

 

[John_H]

I'm an electronics engineer - I _know_ how to check
wiring.

That oughta stir up a few leccies!

 

[Poxy]

Phil is, most likely, quite correct. I have a double insulated
vacuum cleaner which does not even have an earth pin
on the 240V plug and I can reliably trip the ELCB by
switching it on and off a few times.

Could that be due to voltage & current being out of phase or something? I'd
be surprised that RF switching hash could be strong enough to trip an RCD.

 

[Phil Allison]

"Poxy" = how well is this dude named ???

Could that be due to voltage & current being out of phase or something?

** RCDs sense current ***only*** - dickhead.

What did you imagine the fucking "C" stands for ???????

I'd be surprised that RF switching hash could be strong enough to trip an
RCD.

** So would I - and that is NOT what I posted !!!!

When an arc is created by a switch opening or BOUNCING at switch on, energy
is lost as radiated power - radiated into space by the cable feeding
current to that arc acting as an antenna. Any AM radio will prove that
fact.

Now - unless the energy radiated by the active and neutral cables is
exactly the SAME - the RCD will sense a current imbalance and TRIP. Some
RCDs may be affected by the radiated RF noise too - and the two effects
can act in unison.

Hence the intermittent nature of the tripping.





............. Phil

 

[Poxy]

"Poxy" = how well is this dude named ???



** RCDs sense current ***only*** - dickhead.

What did you imagine the fucking "C" stands for ???????





** So would I - and that is NOT what I posted !!!!

When an arc is created by a switch opening or BOUNCING at switch on,
energy is lost as radiated power - radiated into space by the cable
feeding current to that arc acting as an antenna. Any AM radio will
prove that fact.

Now - unless the energy radiated by the active and neutral cables is
exactly the SAME - the RCD will sense a current imbalance and
TRIP. Some RCDs may be affected by the radiated RF noise too - and
the two effects can act in unison.

Hence the intermittent nature of the tripping.

Thank you for the amplification - I had never heard of this "imbalance of
energy radiating into space" explanation for RCD tripping, nor the issue of
sensitivity to RF noise.

Perhaps it could have been provided without the accompanying invective?

 

[Blutt]

That oughta stir up a few leccies!

Nope , that's when we turn off, engineers know everything, no point in
trying to explain anything to them!
JKM

 

[Phil Allison]

"Poxy"

Thank you for the amplification - I had never heard of this "imbalance of
energy radiating into space" explanation for RCD tripping, nor the issue
of
sensitivity to RF noise.

** You have never heard of any damn thing - shithead.

Perhaps it could have been provided without the accompanying invective?

** There was none to those issues - you fucking LIAR .




............. Phil

 

[Poxy]

"Poxy"


** You have never heard of any damn thing - shithead.

I'm not sure if that's entirely true nor fair a judgement to make on your
part, but as I said, I certainly wasn't up on the space radiation thing.

** There was none to those issues - you fucking LIAR .

I guess you are right, perhaps I should have said the preceeding invective.

That said, given the placement of explitives in your newer response, I think
"accompanying" is now entirely appropriate.

Anyhoo, that's just semantics. The gist of what I was suggesting, however
poorly communicated, is that your point was well made without resorting to
intemperate language.