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| regardless of the value of the current flowing in the relay coil. Typical connections for overcurrent relays are shown in Fig. 13-6C. |

| The time-current characteristics of this type of relay may be altered to change the time for closing the contacts by varying the distance the relay disc has to travel to close them. The current characteristic is made to vary by taps on the relay coil, which, with a fixed current flowing, will cause the rotation of the disc to speed up or slow down. |

| Combination Types.. |

| Although rapid clearing of short circuits is important, it is often necessary to provide an intentional time delay in relay operation in order to ensure selectivity between individual relays or between relays and fuses. To overcome this difficulty, two overcurrent relays can be placed together in the same case: a time-relay induction element and a small, instantaneous, plunger type of overcurrent element, known as the instantaneous attachment (Fig. 13-7). The instantaneous element can be set to be much higher in current than the tap setting of the time-delay element. The coils of the two elements are in series and their contacts in parallel. |

| Figure 13-6 Induction type of overcurrent relay: (A) Elementary type. |

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