Demonstrating the impact of DC leakage in Type AC RCDs
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- čas přidán 6. 09. 2024
- #SparkyNinja #Electricians #CPD
Again thanks to the e5 group for lending me this demo rig.
This rig demonstrates how DC leakage disables Type AC RCDs from operating within their normal expectation.
Nicely presented Mr Ninja.
That's a nice demonstration of the problem with AC breakers. I didn't realise it was quite that much of an effect
Amazing mate thank you. Finally I get to see the effect of DC earth leakage!
Great practical demonstration, struggle with theory sometimes. 👍
Brillient example of saturation thanks. Just wait until we all need EMC filters on the incomers and active harmonic filters on the network to counteract the harmonic distortion on the network from all of the DC rectification lol! 😂
That’s our buddy 👍👍👍👍👍
Why are the wholesalers still selling them then...cost? Reg amendment needed?
Because they are cheaper, as he said, they are illegal in continental Europe.
Nice to have you back Dave 👍
Hi Sparkie Ninja,
Great demonstration and wondered if I could get a wiring diagram to make a similar rig to demonstrate this in Australia to Electrical apprentices.
Cheers
Steve
Good vid sparky ninja keep up the good vids
Another great educational piece from Mr Watts, though it does make me think that me striving to be efficient with my 4kW solar PV and DC driver LED lighting may bite me on the bum when it comes to AC RCD safety in as much as it is a contradiction and my RCDs won't protect me now due to DC saturation.
I want to go to RCBO DB, is the DC saturation effect applicable to a RCBO type of setup?
The challenge here is identifying or even quantifying values of potential leakage, and of that if any leakage is DC in nature.
Its early days, but this is where things are going for RCD selection. For now manufacturers will give some examples of typical types of equipment,
I recommend doing a google search for RCD types and a company like Doepke that do some good info on this.
Another great video explains the issue
It’s an interesting demo, but lacking in some regards. The test is done with 50mA and 250mA DC current which is much higher than Type A RCDs are specified to handle.
Can you repeat the test with Type A RCDs which are only specced to work up to 6(!)mA DC current and demonstrate that Type A RCDs would really be superior in a significant way?
Can you repeat the test with Type AC RCDs and only 6mA DC current to check if the common AC RCDs are really significantly less responsive?
Can you replicate a realistic fault condition caused by an electronic device that has actually prevented an RCD from tripping?
A discussion on the engineering forum IET EngX indicates that the demo is this video is insufficient or irrelevant. Please consider the points I raised and make another video.
Hi Christian, thanks for your message. This video was just to demonstrate the impact of DC on an AC RCD. The rig originated from the Rail sector where traction current can be imported into the public supply network at values significantly higher than 1 amp.
I haven't explored the idea of creating a 6mA DC leakage device for the type A question. I will look into it.
Great info thanks for doing this
This is an excellent demonstration thank you very much.
This video has caused a bit of a stir on the IETs wiring and regulations forum, with one engineer saying it's 'severely misleading'. See: communities.theiet.org/discussions/viewtopic/1037/26118
SparkNinja, please could you explain how DC gets back into the neutral. Almost all PSU's in all equipment begin with an isolating transformer. So getting a pulsed "dc" signal back that way is not impossible but tricky. (Pulses only occurring on one side of the cycle). Beyond the PSU there is often a capacitor and very high resistance resistor to the chassis to prevent charges building and that would provide a very small current to earth. (In fact this used to be the cause of quite high earth currents in large office buildings.)
Please could you direct me to, or give examples of how DC gets into the neutral?
Did you ever find an explanation? I'm looking for one myself.
@@nicolajkl No. Though I can see how low cost switched supplies could load and distort one half of the ac to create an "artificial DC" I have not seen any clear papers or videos.
The old D-Lok technique.
Really good video we really need a new design of RCD for DC and AC faults from my knowledge of electronics that would not be expensive
Not sure of the origin of DC leakage to earth is in an AC circuit, what the implications are, how AC leakage to earth interacts with DC leakage to earth, how to measure or detect DC leakage to earth in an AC circuit?
Switchmode power supplies introduce DC currents.
I have a board with 12x Proteus b type ac rcbos . The A type rcbo is currently not available from cef . Should I be concerned yet or will they come out soon to swap a few. All trip buttons work and test well at present
Great video
Is it possible to measure dc current with the ac supply energised? I’m talking about practical on site methods rather than maybe using an oscilloscope???
Yes. I'm sure there is a leakage dector that works in a similar way to a ct
Great vid. Thanks. 🐵
Nice video Dave.
Curiously similar to an older John Ward called 'Effects of DC on Type AC RCDs. Hmmmn
It's exactly the same rig. These videos were made weeks apart.
Why you wired earth to neutral?
Simulating a tncs supply?