This technical report refers to the electrical protections of all 132kV switchgear. These settings may be revaluated during the commissioning, according to actual and measured values. Protection selectivity is partly considered in this report, and could be also revaluated. Names of parameters in this calculation may differ from those in 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 normal tap (12 no.) | 10.15% / 13.20 % |
| Type of tap changer | On load |
| Voltage at maximum tap (V) | 145200 |
| Voltage at 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 normal tap (12 no.) | 10.15% / 13.20 % |
| Type of tap changer | On load |
| Voltage at maximum tap (V) | 145200 |
| Voltage at 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
11kV Outgoing Protection Settings
SEL-551C LT Over-Current and Earth Fault
CDG21 LT Neutral Standby AC series Earth Fault
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