Mf in the secondary winding of current transformer ct

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Unformatted text preview: ary winding of current transformer (C.T.) is insufficient to operate the trip coil of the breaker but the contacts can be opened (and hence the circuit can be opened) by manual or remote control. When a fault occurs, the resulting overcurrent in the C.T. primary winding increases the secondary e.m.f. This energises the trip coil of the breaker and moving contacts are pulled down, thus opening the contacts and hence the circuit. The arc produced during the opening operation is quenched by the oil. It is interesting to note that relay performs the function of detecting a fault whereas the circuit breaker does the actual circuit interruption. 4. Relays. A relay is a device which detects the fault and supplies information to the breaker for circuit interruption. Fig. 16.1 (ii) shows a typical relay circuit. It can be divided into three parts v iz. (i) The primary winding of a *current transformer (C.T.) which is connected in series with the circuit to be protected. The primary winding often consists of the main conductor itself. (ii) The second ci...
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