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In electronics and electrical engineering, a fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby stopping or interrupting the current.
A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) [a] is an electrical safety device that interrupts an electrical circuit when the current passing through a conductor is not equal and opposite in both directions, therefore indicating leakage current to ground or current flowing to another powered conductor.
Where devices are vulnerable to reverse polarity of a signal or power supply, a diode may be used to protect the circuit. If connected in series with the circuit it simply prevents reversed current, but if connected in parallel it can shunt the reversed supply, causing a fuse or other current limiting circuit to open.
A magnetic starter has a contactor and an overload relay, which will open the control voltage to the starter coil if it detects an overload on a motor. [1] [2] The overload relay opens a set of contacts that are wired in series with the supply to the contactor feeding the motor. The characteristics of the heaters can be matched to the motor so ...
Residual-current device (RCD), or residual-current circuit breaker (RCCB) — detects current imbalance, but does not provide over-current protection. In the United States and Canada, these are called ground fault circuit interrupters (GFCI). Residual-current circuit breaker with overcurrent protection — combines the functions of a RCD and a ...
Electromechanical protective relays operate by either magnetic attraction, or magnetic induction. [9]: 14 Unlike switching type electromechanical relays with fixed and usually ill-defined operating voltage thresholds and operating times, protective relays have well-established, selectable, and adjustable time and current (or other operating parameter) operating characteristics.
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Switchgear is a combination of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switches are safe to open under normal load current (some switches are not safe to operate under normal or abnormal conditions), while protective devices are safe to open under fault current.