Substation.ppt
- 1. Tranning During Visit I J.P.PANDYA I HET-MIRACLE ELECTROTECH PVT. LTD-BHAVNAGAR Welcomes to You all my Family members
- 2. BASIC CONSTRUCTION USE OF CT & CVT MAINTANANCE CARE BASIC WIRING DETAILS FAILURE MODE CT AND CVT
- 3. Construction of Current Transformer Various Part :-
- 4. Type of construction and difference Live Tank Design Dead Tank Design Weight at Top Weight at bottom Short Primary length Longer Primary length Main Insulation at top Main insulation at bottom Failure generally in top chamber Failure normally at bottom Special precaution must be taken to pass fault current from top chamber to earth Fault current passes through the primary winding safely up to the earthed bottom tank Suitable for high currents even above 2000 Amps Suitable for currents up to 2000 Amps
- 5. Safety Point of view difference Live Tank Design Dead Tank Design Possibilities of fire and blast is higher because fault occurred at Live HV Side Voltage level Possibilities of fire is less.
- 6. Dead tank CT Winding Primary winding Secondary WDG
- 8. Dead Tank & Live Tank Photos
- 10. Parts of CT::
- 13. Detail On Name Plate Primary Terminal And CT Ratio Nos. of Core used in CT Rated Burden Accuracy Class And ALF Knee Point Voltage Type of Cooling Tan Delta Value LOI / A-T No YEAR OF MFG.
- 14. Use of CT For Metering. : Measurement of Current – Which is in put quantity to meters for measurement and display For Protection. : Measurement of Current – Which is in put to relays like O/C, E/F, Differential , Distance , Bus Bar protection etc
- 15. Metering Core And Termination Generally 1- St Core of CT is used for Metering and hence having class of accuracy 0.2 / 0.2 S / 0.5 / 1.0 1S1-1S2-1S3 are the terminal on CT secondary Box If we choose ratio: 1200 Amp then full secondary winding comes in picture and Terminals are 1S1- 1S3 Similarly For 600 Amp Terminals are 1S1-1S2
- 16. Back Up Protection Core And Termination This CT name plate details shows : Class of accuracy is 5 P 10 And Burden is 15 VA This core i.e. 2nd Core is for Back up protection O/C And E/F relay function as in put current. We connect wires on 2S1- 2S2 For 600 Amp And 2S1-2S3 For 1200 Amp.
- 17. Differential or Distance Protection Core And Termination Third core of This detailed CT with Accuracy class PS: Knee Point Voltage : 950 Volt @ 1200/ 1 A. For 1200 /1 Amp : 3S1- 3S3 And 600 /1 Amp : 3S1- 3S2 Other Cores if available it is 4th and 5th. In CTs of 132 KV And above class in GETCO For Bus Bar protection Scheme all these core of PS Cl.
- 18. What is Knee Point ?
- 19. Ferrules practice D – FOR METERING C – FOR BACK UP PROTECTION A – FOR DIFFERENTIAL / DISTANCE B – FOR BUS BAR PROTECTION
- 20. Metering CT Metering CTs are having Secondary with 1 Amp or 5 Amp in GETCO Why in 11 KV At 5A ? 66 KV And Above at 1 A ?
- 21. CT Ferrules at MK Box A>> Metering Circuit :: - R-Phase CT : R1S1- R1S2 (Metering) Y-Phase CT : Y1S1-Y1S2 (Metering) B-Phase CT : B1S1- B1S2 (Metering) Pilot wire S1 And Star Point S2 Hence All 1S2 points are shorted and earthed at Yard MK
- 22. For similar we can do for Back up and Differential • For Back UP Protection : “ C ” We Use • R- Phase C 11 • Y-Phase C31 • B- Phase C51 • Star Point C71 • And For Differential / Distance : “A” We use • A11 , A31 , A51, A71
- 23. 66 KV CT Failure – Live Tank
- 24. Bus Coupler CT – 220 KV Savar kundla:
- 25. 220 kv CT failure Vartej:28-02-10
- 26. Live Tank CT Failure Photographs
- 27. Dead Tank CT Failure Photographs
- 28. Maint. Check Point For Current Transformer : • Checking daily for any leakage of Oil or for corona and for abnormal noise ,or any hot glow etc. • Periodic Checking of IR Value and Tan Delta of CT & Condition of Oil and nitrogen pressure if CT Without Bellow • Checking of Knee Point voltage and ratio test and Secondary Wdg. Resistance measurement .
- 29. Reasons for failure of CTs. > Low IR Value (Failure of insulation) >High Tan Delta Value >Opening of secondary Wdg. >Primary winding joint opening during fault. >Loose / no proper earthing connection at tan delta point
- 30. CVT : Capacitive Voltage Transformer Generally provided for dual purpose of communication and for monitor line voltage and frequency Where Two line parallel operation either of Generation or of other grids then checking of Voltage / Frequency /Phase sequence condition is essential before make it parallel
- 31. CVT Use: >One Line having CVT and secondary side There will be decided voltage 110 V A.C >This voltage is used to compare with Bus PT and Phase sequence through Synchronization trolley.
- 33. General Ckt Dia. for CVT V1 V2 C1 C2 Secondary Voltage Circuit Diagram of a C.V.T Secondary Voltage V2 C1 C2 Equivalent Circuit V1 ___ V2 = 1+ ___ Notes: ______ Where K- Factordepending upon losses in Capacitors and Electro-magnetic Portion O - Phase error change in Minutes/Hz Maximum Output from a C V T=K(C1+C2) V2 2 C 2 C 1 Protective Spark Gap
- 35. Maint. Care To be taken for CVT Cleaning of porcelain insulators Checking of secondary connections Measurement of IR value and Tan Delta as per OEM Recommendation Never store in horizontal position.