representatives meeting - pfiffner group · representatives meeting june 7, 2017 . / page 2 /...

Oil insulated instrument transformers

Reimund Gross Product Manager High-Voltage ITs

[email protected]

Representatives Meeting June 7, 2017

mailto:[email protected]

www.pfiffner-group.com / page 2 / 12.06.2017

Outdoor instrument transformers

Current transformers

24 – 550 kV

Combined transformers

24 – 170 kV

Inductive VT

24 – 245 kV

Capacitive VT

72 – 550 kV

Current transformers


Oil-paper insulated

24 – 550 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

Inductive voltage transformers


Oil-paper insulated

24 – 245 kV

Working at low induction

With open delta winding and

damping unit Ferro resonance can

be minimized

Generously-sized terminal box

EOF 123 EOF 245

Combined instrument transformers


Oil-paper insulated

24 – 170 kV

Combines all advantages of

current and voltage transformers

Guaranteed accuracy over entire

service life

New member of Oil – Family:

EJOF 123 – 170 G

Capacitive voltage transformers


Oil-paper insulated

72 – 550 kV

Ferro-resonance-free

Custom made design

Various features available

Combined Transformer – cross section


Bellows cover with oil

expansion indicator

Lifting lugs

CT part with iron cores, secondary

windings and high voltage insulation

Bushings

VT part primary winding

and high voltage insulation

Terminal box with rating plate

Iron core of VT

Main earth terminal

Expansion bellows

Housing with drainage area

Primary terminal

Primary reconnection

Secondary windings

Oil drain valve

Composite vs. Porcelain insulator

Composite

Important improve of the explosion

security

Considerable better behaviour

under rain and heavy pollution

Hydrophobicity


Composite Insulator - Hydrophobicity


New 21 years in industrial

environment

Porcelain

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

Composite vs. Porcelain insulator

Composite

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


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


Secondary terminals

Pfiffner Instrument transformers 123-525kV are equipped with an easy

primary reconnection.

Access only from one side necessary (P2).

One single pad to modify the ratio.



Pfiffner Instrument transformers 123-525kV 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

300-600-1200/1

Number of primary turns: 1 : 2 : 4

Number of secondary turns: 1200



Special primary reconnection for higher currents (> 3000 A)

Special, expensive parts (copper parts, flex parts)



Example of ratios


Ratio Number of primary turns Number of secondary turns

600-1200-2400/1 1 : 2 : 4 1) 2400

150-300-600/1 2 : 4 : 8 1) 1200

2000-4000/1 1 : 2 2) 4000

1000-2000/1 1 : 2 1) 2000

200-400/1 3 : 6 1) 1200

200-1200/1 1 : 6 1) 1200

100-200-800/1 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)

1200-2400/1

Number of primary turns: 1

Number of secondary turns: 1200-2400


Secondary tapping

P1 P2

1S1 1S2 1S3 2S1 2S2 2S3 3S1 3S2 3S3 4S1 4S2 4S3 5S1 5S2 5S3

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)


Unbalance CT for MSCDN application

Ratio Number of primary turns Number of secondary turns

1/1 50 50

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


Special test: Internal arc


Classification

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

IEC 61869 describes internal arc test as special test

In general the defined currents are too high, because phase to ground

currents are lower than phase to phase currents which define Ith

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.


Special test: Internal arc


Internal arc test on JOF 245 G

Pfiffner Tests available for

JOF 24 – 170 (small head) 12 kA / 20 kA

JOF GXP head: 31.5 / 40 kA

EOF 24 – 170: 12 kA

EJOF 24 – 170: 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


Executed internal arc tests

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


Conclusion

Thank you for your attention


Questions / discussion

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representatives meeting - pfiffner group · representatives meeting june 7, 2017 . / page 2 /...

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