Representatives Meeting June 7, Oil insulated instrument transformers Reimund Gross Product Manager High-Voltage ITs

Transcription

1 Representatives Meeting June 7, 2017 Oil insulated instrument transformers Reimund Gross Product Manager High-Voltage ITs

2 Outdoor instrument transformers Current transformers kv Inductive VT kv Combined transformers kv Capacitive VT kv / page 2 /

3 Current transformers Oil-paper insulated kv Head type with two head sizes, up to 72 kv also tank type available Simple primary winding changeover Explosion tested housing JOF 123 JOF 420 G / page 3 /

4 Inductive voltage transformers Oil-paper insulated kv Working at low induction With open delta winding and damping unit Ferro resonance can be minimized Generously-sized terminal box EOF 123 EOF / page 4 /

5 Combined instrument transformers Oil-paper insulated kv Combines all advantages of current and voltage transformers Guaranteed accuracy over entire service life New member of Oil Family: EJOF G / page 5 /

6 Capacitive voltage transformers Oil-paper insulated kv Ferro-resonance-free Custom made design Various features available / page 6 /

7 Combined Transformer cross section Bellows cover with oil expansion indicator Lifting lugs CT part with iron cores, secondary windings and high voltage insulation Expansion bellows Housing with drainage area Primary terminal Primary reconnection Bushings VT part primary winding and high voltage insulation Terminal box with rating plate Secondary windings Iron core of VT Main earth terminal Oil drain valve / page 7 /

8 Composite vs. Porcelain insulator Composite Important improve of the explosion security Considerable better behaviour under rain and heavy pollution Hydrophobicity / page 8 /

9 Composite Insulator - Hydrophobicity New 21 years in industrial environment / page 9 /

10 Composite vs. Porcelain insulator Composite Porcelain Important improve of the explosion security Considerable better behaviour under rain and heavy pollution Hydrophobicity Easier handling due to lower weight and less fragility Reduce over all weight of the instrument transformer Less risks of damages during transport and installation Less risks of vandalism long term experience reliable Use of single shed or alternating shed design Use of porcelain type C130 (aluminium oxide) Cementing up to 245kV in house / page 10 /

11 Secondary terminals Screw terminals Woertz Spring-type terminals Wago Tobjob Bolt terminals M10 Pfiffner design Other terminals on request e. g. Phoenix, Weidmüller, Conexel most customer requirements can be fulfilled / page 11 /

12 Primary reconnection Pfiffner Instrument transformers kV are equipped with an easy primary reconnection. Access only from one side necessary (P2). One single pad to modify the ratio. / page 12 /

13 Primary reconnection Pfiffner Instrument transformers kV are equipped with an easy primary reconnection. Access only from one side necessary (P2). One single pad to modify the ratio. Clear schematic diagram for connection incl. max. torque for screws. Reduces risks of wrong connection to an absolute minimum. 300 A 600 A 1200 A / page 13 /

14 Primary reconnection /1 Number of primary turns: 1 : 2 : 4 Number of secondary turns: / page 14 /

15 Primary reconnection Special primary reconnection for higher currents (> 3000 A) Special, expensive parts (copper parts, flex parts) / page 15 /

16 Example of ratios Ratio Number of primary turns Number of secondary turns /1 1 : 2 : 4 1) /1 2 : 4 : 8 1) /1 1 : 2 2) /1 1 : 2 1) /1 3 : 6 1) /1 1 : 6 1) /1 1 : 4 : 8 1) 800 1) : Standard primary reconnection (double or triple ratio) max. Icth = 3000 A (on highest ratio) 2) : High current reconnection (only double ratio) max. Icth = 4500 A (on highest ratio standard head) max. Icth = 5000 A (on highest ratio G head) / page 16 /

17 Secondary tapping /1 P1 P2 1S1 1S2 1S3 2S1 2S2 2S3 3S1 3S2 3S3 4S1 4S2 4S3 5S1 5S2 5S3 Number of primary turns: 1 Number of secondary turns: / page 17 /

18 Unbalance CT for MSCDN application MSCDN : Mechanical Switched Capacitor with Damping Network Current ratio 1:1 A / 5:5 A / 10:1 A or similar Usually 1 or 2 Protection Cores (ex: 10 VA 5P10) Ratio Number of primary turns Number of secondary turns 1/ / page 18 /

19 Special test: Internal arc Some Markets require Special Test «Internal arc» e.g. France, Canada, Poland, Internal arc is the failure of high voltage insulation inside the instrument transformer short-circuit to ground Arc is vaporizing the oil High and fast increase of internal pressure of IT Housing explodes -> high accident risk for persons in substation Test shall proof a «controlled» bursting of housing without ejection of parts / page 19 /

20 Classification IEC describes internal arc test as special test Possible with oil insulated IT and tested by Pfiffner Possible with oil insulated IT, but not tested by Pfiffner NOT possible with oil insulated IT / page 20 /

21 Special test: Internal arc In general the defined currents are too high, because phase to ground currents are lower than phase to phase currents which define I th Small currents < 20 ka with standard design possible For currents >= 20 karms expensive design with rupture discs and enforced housings necessary Is the customer willing to pay extra for this design? Development for VT stopped due to high cost pressure from Market Don t make active marketing with internal arc test. / page 21 /

22 Internal arc test on JOF 245 G / page 22 /

23 Executed internal arc tests Pfiffner Tests available for JOF (small head) JOF GXP head: EOF : EJOF : 12 ka / 20 ka 31.5 / 40 ka 12 ka 12 ka Tests are Expensive: Laboratory cost and Instr. Transformer which will be destroyed rare number of laboratories which perform internal arc test. IEC standard lets a lot of room for interpretation of test execution Pfiffner proposal: 1. Dielectric routine test on test object must be fulfilled, 2. install arc initiation (wire / nail) 3. Execute internal arc test / page 23 /

24 Conclusion The important developments take place with non-conventional technologies Oil ITs are mainly adapted to requirements of new markets, e.g. RTE France, NG England Some special customer adaptions are opposing standardisation for cost reduction / page 24 /

25 Questions / discussion Thank you for your attention / page 25 /