RCD teardown

This is a teardown of 230V 16A AC RCD/GFCI based on CL4145 IC. The control IC senses fault current with differential current transformer and drives solenoid that keeps output contacts closed when everything is ok.






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  1. Tomi Engdahl says:

    Ham Radio Trips Circuit Breakers

    Arc-fault circuit breakers are a boon for household electrical safety. The garden-variety home electrical fire is usually started by the heat coming from a faulty wire arcing over. But as any radio enthusiast knows, sparks also give off broadband radio noise. Arc-fault circuit interrupters (AFCI) are special circuit breakers that listen for this noise in the power line and trip when they hear it. The problem is that they can be so sensitive that they cut out needlessly.

    Our friend [Martin] moved into a new house, and discovered that he could flip the breakers by transmitting on the 20-meter band.

    And of course, it’s a known problem in the Ham community. In particular, one manufacturer has had serious problems misinterpreting intentional radiation

    RFI to Ground-Fault Circuit Interrupters

    Ground-Fault Circuit Interrupters (GFCI) and Arc-Fault Circuit Interrupters (AFCI) circuit breakers are occasionally reported to “trip” (open the circuit) when a strong RF signal is present, usually a ham’s HF transmissions.

    Under current codes, GFCI protection is required for all basement outlets, outdoor outlets, and for outlets in kitchens and bathrooms. AFCI protection is also required for all circuits that supply other specified rooms, such as bedrooms.

    RF interference to GFCI breakers is caused by RF current or voltage upsetting normal operation of the imbalance detection circuit, resulting in the false detection of a fault. Similarly, RF current or voltage could upset the arc detection circuitry of an AFCI breaker.

  2. Tomi Engdahl says:

    A Floureon branded socket outlet with built in RCD is tested and taken apart. Also shows how RCDs are tested that they work correctly.

    Floureon RCD Socket Tested & Dismantled

    How to Test RCDs

    Demonstration of testing an RCD, different test settings, expected results and alternate test method for situations which have two or more RCDs on the same circuit.

  3. Tomi Engdahl says:

    Safety device uses GMR sensor

    This Design Idea presents a differential safety device to prevent risks arising from current leakages in household applications. The proposed circuit uses a new method for differential current sensing (Figure 1). The method entails the use of Helmholtz coils and a magnetic sensor based on the GMR (giant-magnetoresistive) effect. The AC004-01 magnetic sensor from NVE uses GMR technology

    Two Helmholtz coils carry the household’s input current. If no differential current between phase and ground exists at the center of the coils, then the magnetic field is uniform and null. But, in the presence of an unbalanced magnetic field, corresponding to a leakage current to ground, a differential magnetic field appears at the center of the Helmholtz coils

    The reference voltage corresponds to the highest allowable leakage current—generally, approximately 30 mA.

  4. Tomi Engdahl says:

    Obsolete Devices: VOELCB Operation and Problems

    Theory of operation and various problems encountered with voltage operated earth leakage circuit breakers.

    These voltage operated devices have not been used in the UK for over 30 years, they are not manufactured any more, and all of them should have been replaced decades ago.

    Unfortunately, there are plenty of buildings which still have them.
    The replacement for one of these old VOELCBs would be an RCD – a current operated device which works in a totally different way.

  5. Tomi Engdahl says:

    Totally exploded Hager RCBO (RCD/GFI with overcurrent trip)

    I’ve always pondered whether cramming the RCD/GFI circuitry into a breaker designed to break up to 10,000A of fault current was a compromise. It turns out it does open up the possibility of an internal flashover.

    My guess for the fault scenario that caused this is that the switching contacts welded shut allowing current to continue flowing, the electronic module tried to trip the welded mechanism, and then burned out initiating an arc that allowed the live to flash over to the neutral.

  6. Tomi Engdahl says:

    “The way of earth leakage” by INDU-ELECTRIC Power Distribution

    General Information on earth leakage and how to adjust a RCD with variable settings.

  7. Tomi Engdahl says:

    DIY tools for checking home RCD Breakers or RCCB Circuit Breaker Tester

    a simple and effective DIY tools for checking home RCD Breakers if they can trip at 30mA and remain stable at 15mA. No RCD Breaker is considered good if failing to meet these 2 requirements.

    This RCD tester does not need the earth line (PE). The tools also help to check if there is small leakage at the load.

    don’t blindly trust the self-test button of the RCCB. You never know how much the simulate current value is. It’s 30mA, 50mA or 100mA. Trust the tool you made yourselves, it is 30mA to 35mA, and if the RCCB (without load) fails to response, it is unsafe to use it.

  8. Tomi Engdahl says:

    How to Test RCDs

    Demonstration of testing an RCD, different test settings, expected results and alternate test method for situations which have two or more RCDs on the same circuit.

    Tester used is a Fluke 1653. Other test equipment may have different ways to select the various test options, but the actual tests will be the same.

  9. Tomi Engdahl says:

    Metal RCD Socket Test & Teardown

    Electrical Testing the Tests Required for an RCD Rated at 30mA or Less


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