Type B RCD is used where DC residual currents could occur, in addition to normal AC, can detect high-frequency AC and pure DC earth leakage currents. The tripping conditions are defined with different frequencies from 50Hz to 1kHz.
Reducing the risk of fire or electrocution through automatic disconnection of the electrical supply relies on the selection of the correct type of RCD. Type B RCD is suitable for loads with three-phase rectifiers, such as variable speed drives, photovoltaic systems, electric vehicle charging stations and medical equipment.
Type A RCD ensures tripping for residual AC currents and pulsating DC currents, type B RCD ensures tripping for residual AC currents, pulsating DC currents and smooth DC currents. The function of type B RCD can include common type A RCD and type AC RCD.
Type B RCD is usually designed with two residual current detection systems.
The first uses a technology similar to type AC and type A RCD, which is independent of voltage. This means that even if the line voltage is lost, residual current faults can still be detected and personnel are still protected.
Another one uses “fluxgate” technology to enable RCD to detect smooth DC currents
With the development of new energy vehicle technology, every household has replaced it with new energy vehicles, and EV Supply Equipment has entered every household at this time.
In the field of electric vehicles, the internal charging topology is more complicated, and the electric vehicle power battery is a DC power supply system. Therefore, the current components are more complicated, including AC current and pulsating current, especially in this special application scenario. In order to protect the safety of life and property, it is recommended to install a Type B leakage circuit breaker with a higher protection level on the EV Supply Equipment.
The solar energy system is from the solar version to the solar control system, and then the frequency conversion control system, and finally distributed to the terminal power distribution system.
Due to the conversion of DC and AC, there are more interference factors inside the system. We need to use the corresponding DC circuit breaker and type B RCD protection equipment and human’s body, it is also necessary to reduce the blinding effect from corresponding interference
The selective trip coordination between RCDs is realized by time delay or circuit subdivision. This method avoids any RCD tripping, except for equipment immediately upstream of the fault location. In order to achieve delay operation, the selective RCD called Type S can withstand the residual current within a specified time without tripping.
By choosing different trip thresholds and tripping times, the distinction between RCDs can be achieved. In addition, in terms of sensitivity to direct current, by selecting RCDs with a higher tripping level for the higher level of the circuit, you will avoid any false interferences caused by direct current. In other words, the lower-level RCD in the circuit, which is closer to the ground leakage fault, will trip faster at the lower threshold. This will isolate the fault and keep the rest of the circuit continuity.
Tongou Electrical offers a full range of RCDs, from additional equipment for circuit breakers to complete residual current circuit breakers (RCCB), including type B, S, and type A rcd models.