ELCB and Lightning

[Vmaxx Kingdom]

Hi guys,
i am from indonesia, i install CCTV system at Highway and the panel equipped with RCD
i need to understand few question

my RCD trip frequently ( in 1 month average 2-3 times)more whose if raining with thunder storm.
info = RCD 40Amp, 0.1mA, earth resistance 0.5 Ohm.
Q1 - Why this always happen
Q 2 - which more sensitive , 0.1mA, 0.01mA, 0.03mA
Q3 - what i have to do to prevent this

 

[Marvo]

earth resistance 0.5 Ohm.

When you say 'earth resistance' what do you mean. How did you measure this? Also what tester were you using when you got this reading?

Q1 - Why this always happen

I think you answered this question when you said it trips when it rains. There's obviously rain water getting into the wiring or components causing a low insulation fault (IR fault).

Q 2 - which more sensitive , 0.1mA, 0.01mA, 0.03mA

Are you sure the figures you listed are right. RCD's usually come in 10mA (0.01A), 30mA (0.03A), 100mA (0.1A) etc. The 100mA is the least sensitive of the three values I gave.

Q3 - what i have to do to prevent this

Find the leak where the rainwater is getting in, fix it and repair any damage.

 

[Vmaxx Kingdom]

1st, i said tq very much for the reply,

earth resistance tested using earth tester.
http://www.kew-ltd.co.jp/en/download/pdf/4102A_4105A_E.pdf


for your info, i do the insulation test for whole circuit and the insulation still good. that mean no short circuit between live and earth, neutral and earth and live to neutral.
if u though :-
1) lightning may course the tripping - this system have lightning arrester . its should be discharge power surge directly to ground is i am right?
2) and no water getting the to equipment, my outdoor panel water resistance

tq again for the reply. hope i get learn something new again.

 

[Engineer54]

You said you IR tested the complete system. So what sort of IR value did you see for the overall (complete) system??

 

[Marvo]

1) lightning may course the tripping - this system have lightning arrester . its should be discharge power surge directly to ground is i am right?

Yes, close proximity lightning could cause RCD tripping. This would be a likely cause if your system is testing good insulation. Surge arrestors will dump to earth when the surge is higher than the clamping voltage.

Can you wire the surge arrestors on to the supply side of the RCD? If not maybe consider an RCD with automatic restart.

I hate Flash websites but this was the best link I could find.

 

[Vmaxx Kingdom]

You said you IR tested the complete system. So what sort of IR value did you see for the overall (complete) system??

live to neutral=230 Ohm
live to earth = 150 Ohm
Neutral to earth = 110 Ohm

 

[Vmaxx Kingdom]

Yes, close proximity lightning could cause RCD tripping. This would be a likely cause if your system is testing good insulation. Surge arrestors will dump to earth when the surge is higher than the clamping voltage.

Can you wire the surge arrestors on to the supply side of the RCD? If not maybe consider an RCD with automatic restart.

I hate Flash websites but this was the best link I could find.

we try to reduce the project cost, this is maintenance after installation project (under warranty)

is there possibility tripping issue course by the earthing rod sharing between lighting arrester and earthing terminal from the panel?

 

[Engineer54]

Are you sure your doing IR tests or resistance tests?? We should be seeing IR results in Meg ohms not ohms.... What test voltage are you using for your IR tests. Hope your not using the low ohm section on your IR tester, or using a multimeter for these tests?? lol!!

 

[Marvo]

i do the insulation test for whole circuit and the insulation still good. that mean no short circuit between live and earth, neutral and earth

live to neutral=230 Ohm
live to earth = 150 Ohm
Neutral to earth = 110 Ohm

You say the insulation tests showed good insulation then you say that 'live to earth = 150 Ohm, Neutral to earth = 110 Ohm'.

These reading do not show that 'the insulation is good'. These readings show low insulation, you need to improve the IR to at least 1 M Ohm live to earth and 1 M Ohm neutral to earth.

Don't waste time replacing or rewiring the RCD, it's doing its job correctly with the readings you've given.

 

[Vmaxx Kingdom]

Are you sure your doing IR tests or resistance tests?? We should be seeing IR results in Meg ohms not ohms.... What test voltage are you using for your IR tests. Hope your not using the low ohm section on your IR tester, or using a multimeter for these tests?? lol!!

lol... yes Meg Ohm. sorry,

 

[Engineer54]

Just realised your working on CCTV equipment. So i doubt if you have been conducting IR tests on that stuff except maybe between L N+E otherwise your electronics will be fried, ...well damaged anyway...lol!!

 

[Marvo]

I assumed he would be doing IR tests at 250volts which should be adequate.

 

[Vmaxx Kingdom]

Just realised your working on CCTV equipment. So i doubt if you have been conducting IR tests on that stuff except maybe between L N+E otherwise your electronics will be fried, ...well damaged anyway...lol!!

i unplug dc equipment and should be not risk my equipment right?

 

[Engineer54]

i unplug dc equipment and should be not risk my equipment right?

Correct, ...You would need to unplug/disconnect all electronic mains power connections to be able to conduct IR tests on supplying/distribution cables, if you want to test between L-N, L-E, N-E at 250V or 500V...!! lol!!