Transformers Protection Schemes Transformers Protection Schemes Some types of power transformersSome types of power transformers

••         300 MVA. 3 Winding Power Transformer300 MVA. 3 Winding Power Transformer             275 KV / 132 KV / 33 KV. (Y.Y.Δ).275 KV / 132 KV / 33 KV. (Y.Y.Δ).

••         75 MVA. & 45 MVA. 2 Winding Power Transformer 175 MVA. & 45 MVA. 2 Winding Power Transformer 132 KV / 33 KV. 32 KV / 33 KV.

••         30 MVA 2 Winding Power Transformer30 MVA 2 Winding Power Transformer     132 KV / 11 KV. 132 KV / 11 KV.

••         20 MVA & 15 MVA 2 Winding Power Transformer20 MVA & 15 MVA 2 Winding Power Transformer    33 KV / 11 KV. 33 KV / 11 KV.             Drawing : single Line diagram for Drawing : single Line diagram for

                   protection scheme protection scheme Click HereClick Here  

300 MVA 3 Winding Power Transformer 300 MVA 3 Winding Power Transformer Protection Scheme.Protection Scheme.

••         Main (A&B) Protection:Main (A&B) Protection:      1. 1. Differential Protection.Differential Protection.     2. 2. Restricted Earth Fault Protection. (both at 275 kv and 132 kv) Restricted Earth Fault Protection. (both at 275 kv and 132 kv)

     side neutral of the star winding. side neutral of the star winding.••           BackupProtection:BackupProtection:

1.1. C.B Fail to trip.C.B Fail to trip.2.2. I.D.M.T Non Direction O/C & E/F relay on 300 KV sideI.D.M.T Non Direction O/C & E/F relay on 300 KV side3.3. I.D.M.T Direction O/C & E/F relay on 132 KV sideI.D.M.T Direction O/C & E/F relay on 132 KV side4.4. Inter Trip (through pilot cable).Inter Trip (through pilot cable).5.5. Buchhols Trip.Buchhols Trip.6.6. Tap Changer Buchhols Trip. Tap Changer Buchhols Trip. 7.7. Oil Temperature Trip.Oil Temperature Trip.8.8. Winding Temperature Trip.Winding Temperature Trip.9.9. Cable oil pressure Low Trip. (for cable tails ) Cable oil pressure Low Trip. (for cable tails ) 10.10. SF6 pressure Low Trip.SF6 pressure Low Trip.

  75, 45 And 30 MVA- 2 Winding Power Transformer 75, 45 And 30 MVA- 2 Winding Power Transformer

Protection Scheme.Protection Scheme.••         Main (A) Protection:Main (A) Protection:      1. Differential Protection. 1. Differential Protection.

     2. Restricted Earth Fault Protection. 2. Restricted Earth Fault Protection.        (At the neutral of the LV. Winding). (At the neutral of the LV. Winding).

••         Backup Protection:Backup Protection: 1.1. Stand-By Earth Fault relay at Stand-By Earth Fault relay at thethe neutral of LV. Winding. neutral of LV. Winding.

2.2. C.B Fail to trip. (For 132 KV. C.B only)C.B Fail to trip. (For 132 KV. C.B only)3.3. I.D.M.T Non Direction O/C & E/F relay on 132 KV sideI.D.M.T Non Direction O/C & E/F relay on 132 KV side4.4. Inter Trip (through pilot cable).Inter Trip (through pilot cable).5.5. Buchhols Trip.Buchhols Trip.6.6. Tap Changer Buchhols Trip. Tap Changer Buchhols Trip. 7.7. Winding Temperature Trip.Winding Temperature Trip.8.8. Cable oil pressure Low Trip. (For cable tails) Cable oil pressure Low Trip. (For cable tails)

  20 & 15 MVA- 33 / 11 KV, 2 Winding Power Transformer 20 & 15 MVA- 33 / 11 KV, 2 Winding Power Transformer

Protection Scheme.Protection Scheme.••         Main (A) Protection:Main (A) Protection:      1. 1.   Differential Protection. Differential Protection.     2. 2.   Restricted Earth Fault Protection. Restricted Earth Fault Protection.

(At the neutral of the LV. Winding).(At the neutral of the LV. Winding).  

••         Backup Protection:Backup Protection: 1.1. Stand-By Earth Fault relay at the neutral of LV. Winding. Stand-By Earth Fault relay at the neutral of LV. Winding. 2.2. I.D.M.T Non Direction O/C & E/F relay on 33 KV sideI.D.M.T Non Direction O/C & E/F relay on 33 KV side3.3. Inter Trip (through pilot cable).Inter Trip (through pilot cable).4.4. Buchhols Trip.Buchhols Trip.

 

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Bus-Bar Protection SchemesBus-Bar Protection Schemes Bus-Bar Protection Schemes.••       500, 400, 275, 220 and 132 KV. Bus-Bar Protection Scheme.500, 400, 275, 220 and 132 KV. Bus-Bar Protection Scheme.

     - Differential Protection For each section of bus-bar. - Differential Protection For each section of bus-bar.     - SF6 Pressure low Trip. - SF6 Pressure low Trip.                                                                     ••       66 and 33 KV. Bus-Bar Protection Scheme.66 and 33 KV. Bus-Bar Protection Scheme.     - - Differential Protection For each section of bus-bar or Arc protection Differential Protection For each section of bus-bar or Arc protection

or Micro switch protection. or Micro switch protection. --                 SF6 Pressure low Trip.SF6 Pressure low Trip.  

••         22 and 11 KV BUS-Bar22 and 11 KV BUS-Bar Protection Scheme.Protection Scheme.     - - Arc protection or Micro switches protection.Arc protection or Micro switches protection.   ••         500, 400, 275, and 220 KV BB section & BB couplers protection 500, 400, 275, and 220 KV BB section & BB couplers protection

scheme.scheme.             - I.D.M.T Non Directional O/C & E/F Relay. - I.D.M.T Non Directional O/C & E/F Relay.             - C.B Fail to Trip. - C.B Fail to Trip.             - SF6 Pressure Trip. - SF6 Pressure Trip.             - Inter Trip (through pilot cable). - Inter Trip (through pilot cable).

  ••         132 KV BB section & BB couplers protection scheme.132 KV BB section & BB couplers protection scheme.             - I.D.M.T Non Directional O/C & E/F Relay. - I.D.M.T Non Directional O/C & E/F Relay.             - C.B Fail to Trip. - C.B Fail to Trip.

  ••         33 KV BB section & BB couplers protection scheme.33 KV BB section & BB couplers protection scheme.               - I.D.M.T Non Directional O/C & E/F Relay. - I.D.M.T Non Directional O/C & E/F Relay.  ••         11 KV BB section & BB couplers protection scheme.11 KV BB section & BB couplers protection scheme.               - I.D.M.T Non Directional O/C & E/F Relay. - I.D.M.T Non Directional O/C & E/F Relay.

  Shunt Reactor Protection Scheme.Shunt Reactor Protection Scheme.

275 &132 KV. Shunt Reactor Protection Scheme275 &132 KV. Shunt Reactor Protection Scheme. . ••         I.D.M.T Non Direction O/C & E/F relay.I.D.M.T Non Direction O/C & E/F relay.••         Inter Trip (through pilot cable – SHR connected through cable C.B. Inter Trip (through pilot cable – SHR connected through cable C.B.

“for 132 kV only”).“for 132 kV only”).••         Buchhols Trip.Buchhols Trip.••         Oil Temperature Trip.Oil Temperature Trip.

••         Winding Temperature Trip.Winding Temperature Trip.••         Cable oil pressure Low Trip. (For cable tails) Cable oil pressure Low Trip. (For cable tails) ••         SF6 pressure Low Trip.SF6 pressure Low Trip.••         C.B Fail to trip. (For 132 KV. C.B only).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.I.D.M.T Non Direction O/C & E/F relay.••         Buchhols Trip.Buchhols Trip.••         Oil Temperature Trip.Oil Temperature Trip.••         Winding Temperature Trip.Winding Temperature Trip.

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