This technical report refers to the electrical protection of all 132kV switchgear. These settings may be re-evaluated during the commissioning, according to actual and measured values. Protection selectivity is partly considered in this report and could be also re-evaluated. The names of parameters in this calculation may differ from those in the appropriate device.
Technical Data of the Lines
Main Line
| Conductor Type | ACSR Lynx |
| Length | 27.8 km |
| Type | ZM Type Tower |
| Positive sequence impedance | 0.1583 + j0.4004 (0.431 ∠68.4°) Ω/ km |
| Zero sequence impedance | 0.3246 + j1.228 (1.27 ∠75.2°) Ω/ km |
| Current capacity (A) | 487 |
Next Line
| Conductor Type | ACSR Lynx |
| Length | 36 km |
| Type | ZM Type Tower |
| Positive sequence impedance | 0.1583 + j0.4004 (0.431 ∠68.4°) Ω/ km |
| Zero sequence impedance | 0.3246 + j1.228 (1.27 ∠75.2°) Ω/ km |
| Current capacity (A) | 487 |
Protection Settings Calculations for Lines
SEL-311C Distance Protection Settings
Distance Zone
Non-Homogeneous Correction Angle
Load Impedance and Load Encroachment
Power Swing Detection/ Out of Step Detection
Switch on to Fault (SOTF)
Fuse failure scheme OR Loss of Potential (LOP)
SEL-351A Back-up Over Current Settings
Back up over current settings
Technical Data of the Power Transformers
Transformers-1
| Type of cooling | ONAN / ONAF |
| Vector Group | Dyn11 |
| Rated Voltage HV (V) | 132000 |
| Rated Voltage LV (V) | 11500 |
| Full Load current HV (A) | 87.48 / 113.72 |
| Full Load current LV (A) | 1004.12 / 1305.35 |
| Rated Power (MVA) | 20 / 26 |
| % impedance at the normal tap (12 no.) | 10.15% / 13.20 % |
| Type of tap changer | On load |
| the voltage at the maximum tap (V) | 145200 |
| Voltage at the minimum tap (V) | 118800 |
Transformers- 2
| Type of cooling | ONAN / ONAF |
| Vector Group | Dyn11 |
| Rated Voltage HV (V) | 132000 |
| Rated Voltage LV (V) | 11500 |
| Full Load current HV (A) | 43.7 / 56.9 |
| Full Load current LV (A) | 502 / 652.7 |
| Rated Power (MVA) | 10 / 13 |
| % impedance at the normal tap (12 no.) | 10.15% / 13.20 % |
| Type of tap changer | On load |
| The voltage at the maximum tap (V) | 145200 |
| Voltage at the minimum tap (V) | 118800 |
Protection Settings Calculations for Power Transformers
SEL-787 Transformer Differential Protection
Differential Pick-up
Slope-1 Setting
Slope-2 Setting
Differential Unrestrained (U87P (Un-restrained Differential Pick-up))
2nd HARMONIC
5th HARMONIC
SEL-351A Transformer HV Over Current
Pick-up Setting
51PP (for phase fault element)
51GP (for earth fault element)
Time Multiplier Setting
11 kV Outgoing Protection Settings
SEL-551C LT Over-Current and Earth Fault
CDG21 LT Neutral Standby AC series Earth Fault
