Need a portable RCBO to trip faster than general

[westward10]

Members on here are offering you sound advice especially in regard to your 'testing' methods. Any more insults to forum members this thread will be gone.

 

[DPG]

Remember also that if you use a time delayed RCD then you probably won't meet disconnection times, depending on what your local regs stipulate.

 

[Energizer]

I have identified the problem and a potential solution.
Thanks to all members

 

[DPG]

I have identified the problem and a potential solution.
Thanks to all members

If you do decide to go to a type S device you may well be compromising safety. The 40mS is there for a good reason.

 

[Energizer]

I remember to begginer electricians to not repeat my test. I know what I'm doing.
This thread is destinated to advanced members who understands the danger of electricity and think twice about the safety of the life

 

[brianmoooore]

Nobody here mentioned the term of ''selective tripping'', when you have 2 RCD in cascade. In my case, I should replace my general RCD by S type one. The selective residual current protective devices have the identification code S.

Those who are lacking the knowledge are scratching the head and leaving out

I mentioned this in post #19 of your other thread.

 

[mainline]

I have identified the problem and a potential solution.
Thanks to all members

Can you enlighten us to the problem and solution ?.

 

[Energizer]

I mentioned this in post #19 of your other thread.

Exactly. Thank you. Only the S type escaped from my attention. I didn't know before about existence of this type of devices. When I've found the selective tripping explanation, this caught instantly my attention

 

[Energizer]

Can you enlighten us to the problem and solution ?.

The problem is that two cascading RCD are tripping in the same time when leak occurs. Because the upstream RCD is not selective.
The potential solution (valid for my laboratory only, let's say) is mentioned in the post #18
I remember to users to not repeat my test if they don't know what they are doing

 

[ipf]

Exactly. Thank you. Only the S type escaped from my attention. I didn't know before about existence of this type of devices. When I've found the selective tripping explanation, this caught instantly my attention

You're obviously finding out new things but if you didn't even know that S type devices existed, it just about sums up the knowledge involved in your ideas.

 

[Energizer]

You're obviously finding out new things but if you didn't even know that S type devices existed, it just about sums up the knowledge involved in your ideas.

What do you want to say? What standard are you applying to estimate the knowledge ''involved in ideas''?

 

[littlespark]

The testing method you are using is inappropriate. You will damage both RCDs and your installation will with lose power because the upstream rcd no longer turns on, or it will become welded shut, and not trip on fault. Making it unsafe.

The 10 or 30mA is the fault current. If you could simulate an 11, 12, 13 mA fault, then you will find the 10 trips and the 30 doesn’t.
Testing live to earth is creating a massive current.
Voltage divided by resistance = amps.
So 230, or 110 or whatever you use divided by near enough zero is going to give very high current, albeit for a very short time.
In fact, this won’t just be stressing the rcd’s but also any cable, socket pins, circuit breakers that the current has to pass through.


There has been explanations already from professional electricians and the general consensus is that it cannot be done.

Your only solution is to separate the circuit you want from the upstream rcd, either giving it its own rcd, reducing the overall total “resting” earth leakage on each or if permissible, running an non RCD protected circuit to where it needs to be and fitting the rcd there.

 

[Energizer]

The testing method you are using is inappropriate. You will damage both RCDs and your installation will with lose power because the upstream rcd no longer turns on, or it will become welded shut, and not trip on fault. Making it unsafe.

I assume the risk and I'll buy new RCD in case of damage. No problem

The 10 or 30mA is the fault current. If you could simulate an 11, 12, 13 mA fault, then you will find the 10 trips and the 30 doesn’t.
Testing live to earth is creating a massive current.
Voltage divided by resistance = amps.
So 230, or 110 or whatever you use divided by near enough zero is going to give very high current, albeit for a very short time.
In fact, this won’t just be stressing the rcd’s but also any cable, socket pins, circuit breakers that the current has to pass through.

I wrote before many times - when you plug in a shorted to the ground device, there is no resistance, there are amps leaking for some ms - no stress for the wires and the RCD is doing their job. Manufacturers did the same thing thousands of times in the lab for measurements and to check when the device will fail.
The RCD is designed to protect people. A human body have different resistance depending on different factors, humidity, etc, but the faulty device don't have resistance. The current is searching the shortest way, allways.
In real life this type of fault is happening very rarely when we don't have a multimeter to test the device before plug in, so no stress for RCD or wires, it will not trip every day. I allways push the test button before and after my experiments to verify if the device is still operational.

There has been explanations already from professional electricians and the general consensus is that it cannot be done.

Well, sorry for my curiosity and motivation to find a solution. For me, "it cannot be done" is the last thing, when I don't have any ideas and there really are no more solutions, proved by real tests or, not economically viable

Your only solution is to separate the circuit you want from the upstream rcd, either giving it its own rcd, reducing the overall total “resting” earth leakage on each or if permissible, running an non RCD protected circuit to where it needs to be and fitting the rcd there.

I added this solution to the list of potential solutions, the same thing with selective tripping solution that requires changing the RCD type, or intelligent RCD, resetting itself safely after a nuisance trip. These solutions are valid but not everywhere.

 

[Energizer]

Today I performed some tests and I obtained what I want without modifying anything in the house. I modified only my portable RCD power strip. When I plug into my security power strip a faulty device (residual current fault) - then my power strip goes off instantaneously and isolate the faulty circuit from the rest of the house, but the main RCD 30mA it's still on! The portable RCD 10mA trips faster than general. Repeated many times - works like a charm. That's what I wanted

Next step is to integrate all in one multi protection RCBO - leakage, short, overload protection, or, add short circuit (phase-neutral) protection to existing circuit. Ultra fast fuse, resetable fuse ... how to deal with shorts ?

 

[Energizer]

If I understand correctly, my portable RCCB has already an integrated fuse rated 63A and 10000 transient cycles.
At 4 transient cycles per day, this fuse will operate for about 6,5 years before blowing up, and at 1 cycle per month - 833 years. I'm right?

 

[mainline]

Today I performed some tests and I obtained what I want without modifying anything in the house. I modified only my portable RCD power strip. When I plug into my security power strip a faulty device (residual current fault) - then my power strip goes off instantaneously and isolate the faulty circuit from the rest of the house, but the main RCD 30mA it's still on! The portable RCD 10mA trips faster than general. Repeated many times - works like a charm. That's what I wanted

Next step is to integrate all in one multi protection RCBO - leakage, short, overload protection, or, add short circuit (phase-neutral) protection to existing circuit. Ultra fast fuse, resetable fuse ... how to deal with shorts ?

What modifications have you made ? Or are you keeping it secret for now due to applying for patent etc.

 

[littlespark]

What modifications have you made ?

Knackered the main rcd I think.

Otherwise, you’ve managed to invent a device that will discriminate between two 40ms RCDs in line.
I’m sure the manufacturers would be interested in investing, because up til now, after 40 years or so, no one has come up with a solution.

 

[mainline]

Knackered the main rcd I think.

Otherwise, you’ve managed to invent a device that will discriminate between two 40ms RCDs in line.
I’m sure the manufacturers would be interested in investing, because up til now, after 40 years or so, no one has come up with a solution.

Yes and it also has zero resistance, we are now destined to carry high currents with cables the size of a hair.

 

[DPG]

This is a prime case of a little knowledge being a dangerous thing.

 

[Energizer]

Knackered the main rcd I think.

Wrong. I tested the main RCD - it works

Yes and it also has zero resistance, we are now destined to carry high currents with cables the size of a hair.

Wow, you have the ability to measure the resistance and size of cables at distance?

This is a prime case of a little knowledge being a dangerous thing.

Well, if a little knowledge is dangerous thing, I will not share my solution (to keep the people in safety). They should use what they find on the market and what the certified electricians are saying and never try testing like me, because it's dangerous
For me it works (without breaking any safety rules) and I'm happy