Hoja Coordinacion Aislamiento

STEP 1: Determination of the representative overvoltages (Urp)

Us = 1.0 p.u =

Power-frecuency Voltage

24.0 Kv phase-to-phase 19.6 Kv (crest)

Temporary overvoltages

Earth faults

Earth-fault factor: k =

1.4

Urp(p-e) en en KV KV =

19.40

Load rejection

Max. Overvoltage en p.u =

1.4

Urp(p-e) en KV = Urp(p-p) en KV =

19.40 33.60

Resulting representative overvolteges 19.40 Kv Phase-to-phase : Urp(p-p) =

Phase-to-earth : Urp(p-e) =

33.60 Kv

Slow-front overvoltages

Overvolteges originating from station 2 Capacitor  switching

Re-energization Ue2 en p.u = Up2 en p.u =

2.9 4.35

Overvolteges originating from station 1

Energization and re-energization

Ue2 en p.u = Up2 en p.u =

2.5 3.75

Ue2 en p.u = Up2 en p.u =

2.6 4.34

Uet en p.u = Upt en p.u =

3.38 5.008

Uet en p.u = Upt en p.u =

2.88 4.258

Uet en p.u = Upt en p.u =

3.00 4.995

Uet en Kv = Upt en Kv =

66.136 98.127

Uet en Kv = Upt en Kv =

56.338 83.43

Uet en Kv = Upt en Kv =

58.788 97.88

 Arresters at line entrance and near transformers transformers :

Ups en Kv =

45

Upl en Kv =

For Line entrance equipment

For other equipment

With or without capacitor switching Uet > Ups Upt > 2 Ups

Capacitor switching at station 2 No

Phase-to-earth : Urp = Ups = Phase-to-phase : Urp = 2Ups = Fast-front overvoltages

45 Kv 90 Kv

Urp(p-e) = Urp(p-p) =

54

Yes 45 Kv 97.88 Kv

Urp(p-e) = Urp(p-p) =

Evaluated in step 2

45 Kv 90 Kv