The fastest RCBO in the world

[brianmoooore]

Out of interest, why do you keep experiencing this regular tripping of your RCDs?

Exactly! You seem to be more intent on shooting the messenger, rather than listening to his warning and acting upon it.

 

[Energizer]

Out of interest, why do you keep experiencing this regular tripping of your RCDs?

I'm searching to have a security device, in this case a power strip with integrated RCD to trigger while the upstream RDC remains ON. Is a question of sensitivity and rapidity. When you buy a fast and sensible RCD that is intended to trigger faster (to protect sensitive devices for example) than other but in real life is useless because I still need to open the main distribution board to reactivate the main RCD. With this portable 10mA RCD or without - is the same thing, the main RCD is triggering. There should be a way to protect small circuits without cutting off all the house.

 

[DPG]

I'm searching to have a security device, in this case a power strip with integrated RCD to trigger while the upstream RDC remains ON. Is a question of sensitivity and rapidity. When you buy a fast and sensible RCD that is intended to trigger faster (to protect sensitive devices for example) than other but in real life is useless because I still need to open the main distribution board to reactivate the main RCD. With this portable 10mA RCD or without - is the same thing, the main RCD is triggering. There should be a way to protect upstream small circuits without cutting off all the house.

But if you are getting repeated tripping of an RCD then you have something wrong somewhere. Are you getting tripping of your RCD?

 

[brianmoooore]

A 10mA RCD trips between 5mA and 10mA. A 30mA RCD trips between 15mA and 30mA. Any differential fault current that exceeds the tripping current of that particular 30mA RCD is equally likely to trip either or both RCDs.
You will only get discrimination if the fault current exceeds the tripping current of the 10mA RCD but is less than that of the 30mA one.
You can, of course, replace the 30mA RCD with a 'S' type delayed version, but then the rest of the circuits supplied by that RCD will not have the required level of protection.

 

[Energizer]

But if you are getting repeated tripping of an RCD then you have something wrong somewhere. Are you getting tripping of your RCD?

No, I don't have repeated tripping. I simulate a fault. Both RCD shuts off when I want only one to shut off, the closest to me and to the fault

 

[Energizer]

A 10mA RCD trips between 5mA and 10mA. A 30mA RCD trips between 15mA and 30mA. Any differential fault current that exceeds the tripping current of that particular 30mA RCD is equally likely to trip either or both RCDs.
You will only get discrimination if the fault current exceeds the tripping current of the 10mA RCD but is less than that of the 30mA one.
You can, of course, replace the 30mA RCD with a 'S' type delayed version, but then the rest of the circuits supplied by that RCD will not have the required level of protection.

When I do the experiment, I touch the phase to the earth wire. There is no resistance (resistance of the wires and the contact point) so the leakage current is maximal. I don't measured the leakage current, but let's say it's 1 A. The fault is located after 30mA and after 10mA RCD. So if the current reaches from 0A to 1A instantaneously, then both RCD will shut off. I'm thinking correctly? What if using a coil in second circuit to slow a little bit the current in the moment of connection and give time to the RCD 10mA to cut off?

 

[Rockingit]

When I do the experiment, I touch the phase to the earth wire. There is no resistance (resistance of the wires and the contact point) so the leakage current is maximal. I don't measured the leakage current, but let's say it's 1 A. The fault is located after 30mA and after 10mA RCD. So if the current reaches from 0A to 1A instantaneously, then both RCD will shut off. I'm thinking correctly? What if using a coil in second circuit to slow a little bit the current in the moment of connection and give time to the RCD 10mA to cut off?

Both RCD's are seeing the same amount of fault current (usually). It doesn't matter if you have a 1A RCD upstream of a 1mA RCD if the fault current is 500A! The only difference, as you've identified, is which trips first.

What you can get are auto-resetting RCD's such as Gewiss' exclusive intelligent RCD, resetting itself safely after a nuisance trip - https://www.voltimum.co.uk/articles/gewiss-exclusive-intelligent-rcd

 

[Energizer]

Both RCD's are seeing the same amount of fault current (usually). It doesn't matter if you have a 1A RCD upstream of a 1mA RCD if the fault current is 500A! The only difference, as you've identified, is which trips first.

What you can get are auto-resetting RCD's such as Gewiss' exclusive intelligent RCD, resetting itself safely after a nuisance trip - https://www.voltimum.co.uk/articles/gewiss-exclusive-intelligent-rcd

Which trips first, that's the question.
Interesting I didn't know about existence of stuff device as ARD, intelligent RCD. Thanks for information

 

[littlespark]

If you are touching phase to earth as an experiment, you are creating a massive fault current. I wouldn’t be surprised if the upstream 30mA is knackered now.

We are now getting away from one rcd covering several circuits to one RCBO per circuit. More expensive of course, but cuts down on nuisance trips.
Only the faulty circuit trips, leaving others on.

 

[DPG]

Which trips first, that's the question.
Interesting I didn't know about existence of stuff device as ARD, intelligent RCD. Thanks for information

It doesn't really matter which trips first. The point is that on a fault like you are describing both devices will start to trip. One may well take slightly longer to complete the operation, but both will trip once the operation has begun.

 

[Intoelectrics]

Extremely small amount of time is the key to my problem.
Logically, to measure any current, leakage current or normal current, we need a time, small amount of time. Now is to manufacturers to build different devices with different sensibility for different applications. I would like to identify the most sensitive RCB.
The electrical wires length in the house comparing to distance to the Sun is nothing, so I assume the speed of current is instantaneous, in my house. The distance between two RCB is too small to have any delay so the waveform is synchronous, I think.

For most intent purposes what we perceive as instantaneous can be described as such, especially such that our senses and reactions are way way slower than the speed in which electricity and light propagates.

But there is no such thing as a cause and effect mechanism which is instantaneous in the way you imagine it.

 

[Energizer]

If you are touching phase to earth as an experiment, you are creating a massive fault current. I wouldn’t be surprised if the upstream 30mA is knackered now.

We are now getting away from one rcd covering several circuits to one RCBO per circuit. More expensive of course, but cuts down on nuisance trips.
Only the faulty circuit trips, leaving others on.

Yes, this in an experiment, test. In real life this happen when a defective device has a fault of insulation - the phase is touching the ground. I'm testing different electrical equipment that could have short circuit or leakage problem. I have seen equipments that works fine 5 minutes then when the resistance is hot it cause short or leakage to the ground and the general RCD switchs off.
Can you give me and example of what you are using to cut off only the faulty circuit? This is exactly what I need. Thanks

 

[DPG]

Yes, this in an experiment, test. In real life this happen when a defective device has a fault of insulation - the phase is touching the ground. I'm testing different electrical equipment that could have short circuit or leakage problem. I have seen equipments that works fine 5 minutes then when the resistance is hot it cause short or leakage to the ground and the general RCD switchs off.
Can you give me and example of what you are using to cut off only the faulty circuit? This is exactly what I need. Thanks

RCBOs are used to give earth leakage protection to individual circuits. They combine over current and earth leakage protection.

If one trips then you only lose that circuit, not the whole system.

 

[Energizer]

It doesn't really matter which trips first. The point is that on a fault like you are describing both devices will start to trip. One may well take slightly longer to complete the operation, but both will trip once the operation has begun.

Here someone reported it managed to cut off only faulty circuit. This is why I'm searching for

 

[DPG]

Here someone reported it managed to cut off only faulty circuit. This is why I'm searching for

RCBOs - see posts above