Question

1500:5 dan VT 3000:1 dalam rekebantuk anda. Lakarkan gambarajah zon perlindungan B42 Rajah 4 1 Figure 4 5/7 KEEE4253 Figure 4 shows 132 kV transmission line system. Line 1-2, 2-3, and 2-4 are 64 km, 64 km, and 96 km respectively. The positive-sequence impedance of the lines 112. L23 and L24 are 0.05+0.50 0.054j0.6 and 0.08+0.8 per km respectively. Design a three-zone distance-relaying system for the relay line L12 on bus 1. Use CT with ratio of 1500:5 and VT 3000:1 in your design. Draw the protection zone diagram. (9 markah/ marks) olantik atau tidak

Answer 1

Tutal inpesbunce impedance ple laugth leugen Live (3.24)32)s2 (3.2+ j384)n ostip5)n/um. CA km L12 (o.054j016)/ km 96 km (o.08rjo.8)/um (168tj6:4). L24 Zoned setting fur: the relay 2, = B0%. of line 42 - 0.8 x(3-24j 32) -(2- 56+ j25:6)sL Zone-2 settings: 2= 120%. of the line L, 1-2x (3.24j 32) = (3.84+j38.4) n Zone- 3 settivgs: Z3- impedance of line 12+ impedauee of the longest line ameng bgt za] =[[s.24j32) + ( 4+68 +j768)] (l0.88tj 108.8) 2 1500:5 CT ratio = VT ratio = 3000:1. impedance see by the relay: Zachual * ratto facto Vapp Iapp CT ratio Tactual Zapp= Vaceta Vachual VT ratio CTratio VT ratio I S00:5 Zachual X - Zactud X(3000:1 - 0.1 x 2cetual.

Rilay settings: Zme I = Z1. x o.1-(0 256+j2.56 Ja 3R = 22 x0.1 = (0.384 + j3.84) r Zme- 2: 23R = 23 xo.1 = (l:088Tjl0.83)2 Zone - 3: (d) laad at bus 3: IOMVA at 0.9 p.f lag. * T23 = -cos'(o.9) 3X132x0.9 = 48. 599 L-25•84° A . Lead at bus 4: 5 MVA at 0.9 leading pf 5X103 V3X132X0.9 Las(o4) 2 24. 299L25.84A- To tal cunant ab bus b Îj-(T23+ T) - 66.4586-9:1702A cunent seen by the relay at bus I, TIR= I, xo) - 0:2215/-91702A . 1500)- at buy t, roling the vottage see = 44 V. 3000 VIR 'mpedance seemat bush, = 198.65/4.P2- 2'1- 198.652 > BBR. i.e. the impedana sear by the relay for the given ond conditian is beynd its žme-3 settings. So, the relays an B12 cril not trip