Transformers Protection Schemes |
Some types of power transformers • 300 MVA. 3 Winding Power Transformer 275 KV / 132 KV / 33 KV. (Y.Y.Δ). • 75 MVA. & 45 MVA. 2 Winding Power Transformer 1 32 KV / 33 KV. • 30 MVA 2 Winding Power Transformer 132 KV / 11 KV. • 20 MVA & 15 MVA 2 Winding Power Transformer 33 KV / 11 KV. 300 MVA 3 Winding Power Transformer Protection Scheme. • Main (A&B) Protection: 1. Differential Protection. 2. Restricted Earth Fault Protection. (both at 275 kv and 132 kv) side neutral of the star winding. • BackupProtection: 1.C.B Fail to trip. 2.I.D.M.T Non Direction O/C & E/F relay on 300 KV side 3.I.D.M.T Direction O/C & E/F relay on 132 KV side 4.Inter Trip (through pilot cable). 5.Buchhols Trip. 6.Tap Changer Buchhols Trip. 7.Oil Temperature Trip. 8.Winding Temperature Trip. 9.Cable oil pressure Low Trip. (for cable tails ) 10. SF6 pressure Low Trip. 75, 45 And 30 MVA- 2 Winding Power Transformer Protection Scheme. • Main (A) Protection: 1. Differential Protection. 2. Restricted Earth Fault Protection. (At the neutral of the LV. Winding). • Backup Protection: 1. Stand-By Earth Fault relay at the neutral of LV. Winding. 2.C.B Fail to trip. (For 132 KV. C.B only) 3.I.D.M.T Non Direction O/C & E/F relay on 132 KV side 4.Inter Trip (through pilot cable). 5.Buchhols Trip. 6.Tap Changer Buchhols Trip. 7.Winding Temperature Trip. 8.Cable oil pressure Low Trip. (For cable tails) 20 & 15 MVA- 33 / 11 KV, 2 Winding Power Transformer Protection Scheme. • Main (A) Protection: 1. Differential Protection. 2. Restricted Earth Fault Protection. (At the neutral of the LV. Winding). • Backup Protection: 1.Stand-By Earth Fault relay at the neutral of LV. Winding. 2.I.D.M.T Non Direction O/C & E/F relay on 33 KV side 3.Inter Trip (through pilot cable). 4.Buchhols Trip. |
Bus-Bar Protection Schemes | ||
Bus-Bar Protection Schemes. • 500, 400, 275, 220 and 132 KV. Bus-Bar Protection Scheme. - Differential Protection For each section of bus-bar. - SF6 Pressure low Trip. • 66 and 33 KV. Bus-Bar Protection Scheme. - Differential Protection For each section of bus-bar or Arc protection or Micro switch protection. - SF6 Pressure low Trip. • 22 and 11 KV BUS-Bar Protection Scheme. - Arc protection or Micro switches protection. • 500, 400, 275, and 220 KV BB section & BB couplers protection scheme. - I.D.M.T Non Directional O/C & E/F Relay. - C.B Fail to Trip. - SF6 Pressure Trip. - Inter Trip (through pilot cable). • 132 KV BB section & BB couplers protection scheme. - I.D.M.T Non Directional O/C & E/F Relay. - C.B Fail to Trip. • 33 KV BB section & BB couplers protection scheme. - I.D.M.T Non Directional O/C & E/F Relay. • 11 KV BB section & BB couplers protection scheme. - I.D.M.T Non Directional O/C & E/F Relay. Shunt Reactor Protection Scheme. 275 &132 KV. Shunt Reactor Protection Scheme. • I.D.M.T Non Direction O/C & E/F relay. • Inter Trip (through pilot cable – SHR connected through cable C.B. “for 132 kV only”). • Buchhols Trip. • Oil Temperature Trip. • Winding Temperature Trip. • Cable oil pressure Low Trip. (For cable tails) • SF6 pressure Low Trip. • C.B Fail to trip. (For 132 KV. C.B only). 33 KV. Shunt Reactor Protection Scheme for both connected to 33 KV Bus-Bar or to tertiary of 300 MVA Transformer. • I.D.M.T Non Direction O/C & E/F relay. • Buchhols Trip. • Oil Temperature Trip. • Winding Temperature Trip. | ||
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