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RCD trip curve

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The protocol for testing common RCDs in IS10101 2020 is fairly typical but I am interested on your take on verifying the stated requirements by  using alternate points on the curve. I have sometimes found with RCBOs that a max trip time on test at x1 produces a result less than 40ms but the device fails on the x5 setting. 

Parents
  • We had a long discussion about this in a thread just over 12 months ago: https://communities.theiet.org/discussions/viewtopic/1037/23532


    I had a similar observation regarding some RCDs not always passing the 5x test after getting 1x well below 40 ms, and put together a table comparing the tests to the Initial Verification objectives in the 18th Ed:


     
    RCD Residual current Rating

    Tests, results and notes

    10 mA

    Conduct both 1x and 5x tests

    Record the 5x result.
    Verifies both additional protection to 643.7 and ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.

    30 mA

    Conduct both 1x and 5x tests. Requires loop impedance less than 1364 Ω if you take into account full volt drop

    Record the 5x result.
    Verifies both additional protection to 643.7 and ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.

    Whilst the full Zs of 1667 Ω presented in Table 41.5 wouldn't provide sufficient current for a 5x test with lower voltages, earth electrode resistance should be limited to 200 Ω so no issues anticipated

    100 mA

    Conduct both 1x and 5x tests. requires loop impedance less than 409 Ω if you take into account full volt drop

    Record the 5x result.
    Verifies ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.

    Whilst the full Zs of 500 Ω presented in Table 41.5 wouldn't provide sufficient current for a 5x test with lower voltages, earth electrode resistance should be limited to 200 Ω so no issues anticipated


    If you are asserting it's unsafe to test the RCD at 5x in domestic, then do and record the 1x, but now you only have verified disconnection at 1 s and compliance with 411.3.2.4, and therefore in domestic this RCD can only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2.

    300 mA

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result.
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 300 mA RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    500 mA

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 500 mA RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    100 mA Type S

    Conduct both 1x and 5x tests. requires loop impedance less than 409 Ω if you take into account full volt drop

    Record the 5x result.
    Verifies ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.


    If you are asserting it's unsafe to test the RCD at 5x in domestic, then do and record the 1x, but now you only have verified disconnection at 1 s and compliance with 411.3.2.4, and therefore in domestic this RCD can only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    300 mA Type S

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result.
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 300 mA Type S RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    500 mA Type S

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result.
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 500 mA Type S RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

Reply
  • We had a long discussion about this in a thread just over 12 months ago: https://communities.theiet.org/discussions/viewtopic/1037/23532


    I had a similar observation regarding some RCDs not always passing the 5x test after getting 1x well below 40 ms, and put together a table comparing the tests to the Initial Verification objectives in the 18th Ed:


     
    RCD Residual current Rating

    Tests, results and notes

    10 mA

    Conduct both 1x and 5x tests

    Record the 5x result.
    Verifies both additional protection to 643.7 and ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.

    30 mA

    Conduct both 1x and 5x tests. Requires loop impedance less than 1364 Ω if you take into account full volt drop

    Record the 5x result.
    Verifies both additional protection to 643.7 and ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.

    Whilst the full Zs of 1667 Ω presented in Table 41.5 wouldn't provide sufficient current for a 5x test with lower voltages, earth electrode resistance should be limited to 200 Ω so no issues anticipated

    100 mA

    Conduct both 1x and 5x tests. requires loop impedance less than 409 Ω if you take into account full volt drop

    Record the 5x result.
    Verifies ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.

    Whilst the full Zs of 500 Ω presented in Table 41.5 wouldn't provide sufficient current for a 5x test with lower voltages, earth electrode resistance should be limited to 200 Ω so no issues anticipated


    If you are asserting it's unsafe to test the RCD at 5x in domestic, then do and record the 1x, but now you only have verified disconnection at 1 s and compliance with 411.3.2.4, and therefore in domestic this RCD can only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2.

    300 mA

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result.
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 300 mA RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    500 mA

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 500 mA RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    100 mA Type S

    Conduct both 1x and 5x tests. requires loop impedance less than 409 Ω if you take into account full volt drop

    Record the 5x result.
    Verifies ADS to 643.7.1 b) for 0.2 s and 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4 and 411.3.2.1.


    If you are asserting it's unsafe to test the RCD at 5x in domestic, then do and record the 1x, but now you only have verified disconnection at 1 s and compliance with 411.3.2.4, and therefore in domestic this RCD can only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    300 mA Type S

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result.
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 300 mA Type S RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

    500 mA Type S

    Not practicable (or perhaps safe) to test at 5x, so we are limited here to testing at 1x.

    Record the 1x result.
    Verifies ADS to 643.7.1 b) for 1 s disconnection.

    I would be able to demonstrate compliance with Regulation 411.3.2.4, but not 411.3.2.1.

    This leads me to assert that the 500 mA Type S RCD may only provide ADS for distribution circuits, and final circuits not covered by 411.3.2.2

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