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In-Country Training On Operation, Maintenance, Protection & Control of 33/11 kV Substation Project Name: Design, Supply, Installation, Testing & Commissioning of 33/11 kV sub-stations with source end feeder bays.   Contract No: BREB/UREDS/W-01A-001/02/2016-2017 BREB/UREDS/W-01A-002/03/2016-2017 BREB/UREDS/W-01A-004/04/2016-2017
  • 1. Transformer Protection
  • 2. Transformer Protection  External 1.Buchholz 2.Prd 3.Thermostate 4.oil level Indicator  Eelectrical 1. Surge arrestors 2. over currents 3. Differential
  • 3. ANSI No. P630C P631 P632 P633 P634 Differential protection 87 2 wind. 2 wind. 2 wind. 3 wind. 4 wind. Restricted earth fault prot. 87G – – 2 3 3 Definite-time O/C protection 50 2 2 2 3 3 Inverse-time O/C protection 51 2 2 2 3 3 Thermal overload protection 49 1 1 1 2 2 Over/undervoltage protection 27, 59 – – 1 1 1 Over/underfrequency prot. 81 – – 1 1 1 Overexcitation protection 24 – – 1 1 1 Current transformer monitor. – option option option option Measuring circuit monitoring 2 2 2 3 4 Limit value monitoring 2 2 2 3 3 Programmable logic 1 1 1 1 1
  • 4. Inverse-Time Overcurrent Protection IDMT1 IDMT2
  • 5. Earth Fault
  • 6. REF protection
  • 7. Differential Protection
  • 8. Transformer Motors Generators
  • 9. Amplitude Matching A B C Winding a Inom, CT, prim, a Vnom, prim, a Vnom, prim, b Sref, prim = Snom, prim, max Inom, CT, prim, b A B C Winding b
  • 10. A B C Winding a 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 A B C Winding b Vector Group Matching
  • 11. A B C Winding a with I0 filtering without I0 filtering A B C Winding b Zero Sequence Current Filtering
  • 12. Over-/Underfrequency Protection Overexcitation Protection Over-/Undervoltage Protection
  • 13. BUCHHOLZ RELAY OPERATION AND PRINCIPLE The Buchholz relay working principle of is very simple. Buchholz relay function is based on very simple mechanical phenomenon. It is mechanically actuated. Whenever there will be a minor internal fault in the transformer such as an insulation faults between turns, break down of core of transformer, core heating, the transformer insulating oil will be decomposed in different hydrocarbon gases, co2 and co. The gases produced due to decomposition of transformer insulating oil will accumulate in the upper part the Buchholz container which causes fall of oil level in it. TESTING & COMMISSIONING DIVISION ENERGYPAC ENGINEERING LTD.
  • 15. The relay is particularly effective in case of: 1. Falling oil level owing to leaks 2. Short circuited core laminations 3. Short – circuits between phases 4. Broken-down core bolt insulation 5. Puncture of bushing insulators inside tank 6. Overheating of some part of the windings ENERGYPAC ENGINEERING LTD.
  • 17. pressure relief device (PRD) The transformer tank filled with cooling liquid is a container subject to internal pressure and then has to be provided with one or more safety valves suitably calibrated for the maximum allowed pressure, so that overpressure caused by internal faults can be instantaneously relieved through the valves, thus avoiding greater damages such as the deformation or even the burst of the tank and the spraying of hot oil with subsequent fire risks. It is necessary to protect the transformer tank with a suitable equipment capable of almost instantaneously discharging overpressure already at he development, before the structure integrity is damaged and the safety valves has just his function TESTING & COMMISSIONING DIVISION ENERGYPAC ENGINEERING LTD.
  • 18. Internal arcing in an oil-filled power transformer can instantly vaporize surrounding oil, generating gas pressures that can cause catastrophic failure, rupture the tank, and spread flaming oil over a large area. This can damage or destroy other equipment in addition to the transformer and presents extreme hazards to workers. The relay is designed to detect a sudden pressure increase caused by arcing. It is set to operate before the pressure relief device. The control circuit should de-energize the transformer and provide an alarm. The relay will ignore normal pressure changes such as oil-pump surges, temperature changes, etc. ENERGYPAC ENGINEERING LTD.
  • 19. Once every 3 to 5 years, the sudden pressure relay should be tested according to manufacturer’s instructions Test the alarm circuit and verify that the correct alarm point is activated. Use an ohmmeter to verify the trip signal is activated or, if possible, apply only control voltage to the breaker and make sure the tripping function operates. ENERGYPAC ENGINEERING LTD.
  • 20. Thanks
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