FFXI Haven - Ваш Источник #1.

Nondirectional overcurrent relays should be tested at several points on the timecurrent curve, allowing suitable intervals between tests for cooling. Measure the reset time and minimum operating current. Check instantaneous element for pickup and contact action at high and low currents. Caution should be exercised so as not to "burn up" the relay when testing on high currents, or continuously testing at lower currents. Test connections for overcurrent relays are shown in figure 11-1.

(2) Directional overcurrent relay. Check the overcurrent element in the same manner as for a nondirectional overcurrent relay. Before testing the overcurrent element, verify the operation of the directional element by simulated fault currents and voltages. Check the minimum operating current of the overcurrent element at normal voltage, and check the contact gap spacing of the directional element. For typical test connections, see figure 11-2.

b. Differential relays. Figure 11-3 shows a typical test connection for a percentage differential type. Check the minimum operating values at zero restraining current and the operating points at several values of restraint. The slope (differential characteristic) and, where applicable, the harmonic restraint feature should also be checked. It may be desirable to trip all circuit breakers from differential relays as a regular testing procedure.

c. Distance relays. Check currents and phase angles, angle of maximum torque, and directional characteristics.

BACK | NEXT

Easy Access To All Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133