RCD Protected Circuit
Quick Details ： Place of origin ： Guangdong ， China （ Mainland ） Product name ： RCD protected circuit Type ： Electric plug Color ： Black/white/grey Product information ： RCD with additional overcurrent protection circuitry (RCBO or GFCI breaker) ： Residual-current and overcurrent protection may...
Place of origin：Guangdong，China（Mainland）
Product name：RCD protected circuit
RCD with additional overcurrent protection circuitry (RCBO or GFCI breaker)：
Residual-current and overcurrent protection may be combined in one device for installation into the service panel; this device is known as a GFCI (ground fault circuit interrupter) breaker in theUSAandCanada, and as an RCBO (residual-current circuit breaker with overload protection) in Europe. In theUS, GFCI breakers are more expensive than GFCI outlets.
As well as requiring both line and neutral inputs and outputs (or, full 3-phase), many GFCI/RCBO devices require a functional earth (FE) connection. This serves to provide both EMC immunity and to reliably operate the device if the input-side neutral connection is lost but live and earth remain.
For reasons of space, many devices, especially in DIN rail format, use flying leads rather than screw terminals, especially for the neutral input and FE connections. Additionally, because of the small form factor, the output cables of some models (Eaton/MEM) are used to form the primary winding of the RCD part, and the outgoing circuit cables must be led through a specially dimensioned terminal tunnel with the current transformer part around it. This can lead to incorrect failed trip results when testing with meter probes from the screw heads of the terminals, rather than from the final circuit wiring.
Having one RCD feeding another is generally unnecessary, provided they have been wired properly. One exception is the case of a TT earthing system, where the earth loop impedance may be high, meaning that a ground fault might not cause sufficient current to trip an ordinary circuit breaker or fuse. In this case a special 100 mA (or greater) trip current time-delayed RCD is installed, covering the whole installation, and then more sensitive RCDs should be installed downstream of it for sockets and other circuits that are considered high-risk.