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.


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