Symmetrical Fault Calculations

Transcription

1 Symmetrical ault Calculations

2 Eample 1 SCC /12.5 Calculate the fault current at

3 Eample 1 SCC /12.5 Step 1: Calculate Base Values I A 11.9ohms 100 Calculate the fault current at

4 Eample 1 SCC 1200 Step 2: Calculate p.u impedances Tpu t old /12.5 Calculate the fault current at

5 Eample 1 SCC 1200 Step 2: Calculate p.u impedances Tpu t old /12.5 Calculate the fault current at utility old old

6 Eample 1 SCC 1200 Step 3: Calculate fault current I pu V pu total pu 10/12.5 Calculate the fault current at

7 Eample 1 SCC 1200 Step 3: Calculate fault current I pu V pu total pu 10/12.5 Calculate the fault current at I I HV LV I Ipu IHV A 2970 A

8 Eample 2 Addition of a Generator SCC / Calculate the fault current at

9 Eample 2 Addition of a Generator Step 1: Calculate impedances SCC / utility old old Calculate the fault current at

10 Eample 2 Addition of a Generator Step 1: Calculate impedances SCC / utility Tpu t old old 0.48 old Calculate the fault current at

11 Eample 2 Addition of a Generator Step 1: Calculate impedances SCC / Calculate the fault current at utility Tpu Gpu t old G old old 2.4 old

12 Eample 2 Addition of a Generator Step 2: Calculate equivalent impedances SCC V 10/ utility Gpu Tpu 0.48 Calculate the fault current at

13 utility 2.4 Eample 2 Addition of a Generator Step 2: Calculate equivalent impedances 1.0V * 2.4 Eq Tpu 0.48 Gpu 0.456

14 Eample 2 Addition of a Generator Step 3: Calculate fault current 1.0V * 2.4 Eq utility 2.4 I V 1.0 pu pu Eq pu Tpu 0.48 Gpu 0.456

15 Eample 2 Addition of a Generator Step 3: Calculate fault current 1.0V * 2.4 Eq utility 2.4 I V 1.0 pu pu Eq pu Tpu 0.48 Gpu I I HV LV I Ipu IHV A 3668 A

16 Eample 1 & 2 Comparison SCC 1200 SCC / / I 7426 Amps I 9170 Amps

17 Eample 3 Presence of transformer & motor SCC / % 2.4 M 2500 HP 0.17 Calculate the fault current at

18 Eample 3 Presence of transformer & motor Step 1: Calculate impedances SCC / utility old old 3 5% 2.4 M 2500 HP 0.17 Calculate the fault current at

19 Eample 3 Presence of transformer & motor Step 1: Calculate impedances SCC / utility old old 3 5% Tpu1 t old M 2500 HP 0.17 Calculate the fault current at

20 Eample 3 Presence of transformer & motor Step 1: Calculate impedances SCC / utility old old 3 5% Tpu1 t old 0.48 M 2500 HP Calculate the fault current at Gpu G old 2.4

21 Eample 3 Presence of transformer & motor Step 1: Calculate impedances SCC 1200 utility Tpu1 Gpu pu 0.48 pu 2.4 pu 10/ % Tpu2 t old M 2500 HP 0.17 Calculate the fault current at

22 Eample 3 Presence of transformer & motor Step 1: Calculate impedances SCC / utility Tpu1 Gpu Tpu pu 0.48 pu 2.4 pu pu M 2500 HP % 2.4 Motor Mpu rating 2500 * pf m old Calculate the fault current at

23 Eample 3 Presence of transformer & motor Step 1: Calculate impedances SCC / % utility Tpu1 Gpu Tpu2 Mpu pu 0.48 pu 2.4 pu pu 7.89 pu M 2500 HP 0.17 Calculate the fault current at

24 Eample 3 Presence of transformer & motor Step 2: Calculate Equivalent impedances SCC V 10/ utility 2.4 Mpu 3 5% Tpu Gpu 7.89 Tpu2 2.4 M 2500 HP 0.17 Calculate the fault current at

25 Eample 3 Presence of transformer & motor Step 2: Calculate Equivalent impedances 1.0V 1.0V utility 2.4 Mpu Gpu Tpu Tpu2

26 Eample 3 Presence of transformer & motor Step 3: Calculate fault current 1.0V I V 1.0 pu pu Eq pu I I HV LV I Ipu IHV A 3844 A

27 Symmetrical ault SCC 1200 SCC 1200 SCC / / / % 2.4 M 2500 HP 0.17 I 7426 Amps I 9170 Amps I 9609 Amps