Post on 09-Feb-2020
Design criteria for instrument transformers
Florian Gegier
PFIFFNER Instrument Transformers Ltd.
Switzerland
The PFIFFNER Group – Organisation, Presence, Product Range
Instrument Transformers – History and outlook
Overview and types
Design criteria for instrument transformers
Modern Challenges/What’s happening in the grid?
Measurement Technology for the 21st Century
Table of Contents
www.pmw.ch / page 2 / 27.08.2017
PFIFFNER Group – Organisation
PFIFFNER Holding Ltd.
Hirschthal, Switzerland
MGC Moser-Glaser AG
Kaiseraugst, Switzerland
PFIFFNER Instrument
Transformers Ltd.
Hirschthal, Switzerland
ALPHA Elektrotechnik AG
Nidau, Switzerland
PFIFFNER Transformatör A.S.
Ankara, Turkey
PFIFFNER do Brasil Ltda
Itajaí, Brazil
PFIFFNER Deutschland GmbH
Itzehoe, Germany
PFIFFNER Technology Ltd.
Est. 1927 by Emil PFIFFNER
Present on all continents, in all climate zones IEC, BS, IEEE, ANSI, ABNT…
…new to the UK!
PFIFFNER Group – Global Presence
www.pmw.ch / page 4 / 27.08.2017
PFIFFNER Group – Product Range
www.pmw.ch / page 5 / 27.08.2017
Bushing type
current transformers
400V
Transformer station
Substation
Substation
Cable current
transformers
Medium voltage
12 – 72 kV
Low voltage
current and voltage
transformers
Support type
current and voltage
transformers
Power plant, generators Generator current
transformers
Transformer Combined transformers,
outdoor operation
High voltage
72 - 550 kV
GIS
substation
GIS current and
voltage transformers
Medium voltage
12 – 72 kV
PFIFFNER Group – Product Range
www.pmw.ch / page 6 / 27.08.2017
Current transformer
JOF 24 – 550 kV
Combined transformer
EJOF 24 – 170 kV
Inductive VT
EOF 24 – 245 kV
PFIFFNER Group – Product Range
www.pmw.ch / page 7 / 27.08.2017
Capacitive VT
ECF 72 – 550 kV
RC Divider
ROF 72 – 550 kV
PFIFFNER Group – Product Range
www.pmw.ch / page 8 / 27.08.2017
Current transformer
JGF 245 – 550 kV Combined transformer
EJGF 245 – 550 kV
Inductive VT
EGF 245 – 550 kV
PFIFFNER Group – Product Range
www.pmw.ch / page 9 / 27.08.2017
High voltage
GIS CT & VT
Medium voltage
Support type CT
Low voltage
CT & VT
Medium voltage
Ring core CT
History and outlook
1936 220 kV Cascade
voltage transformer of Emil
Pfiffner.
Since 120 years inductive ITs for billing, metering and protection
purpose
British patent from 1887, voltage transformer from 0.1V to 10kV
1930s: 110kV to 220kV systems
1950s: 300kV to 420kV systems
Current topics today UHV with voltage levels up to
1.2 MVAC and ±800 kVDC
Future:
Non-conventional types
New challenges for grid operators and IT manufacturers
Overview and types
Conventional types
Inductive voltage transformer
Capacitive voltage transformer
Inductive current transformer
Divider (C/RC/R - type)
Pockels/Piezo effect
Zero-flux
Rogowski coil
Faraday effect
Shunt
AC
AC
AC
AC (DC)
DC
AC
AC DC
AC DC
AC
AC DC
Non-Conventional types
Criterion 1: Transformation Ratio
N
A
1a
1n
Prim
Sec
Sec
PrimCT
N
N
I
Iratio
ISec
P1
P2
S1
S2
burden NSec
NPrim
Θ=Σ I
Φ
Voltage transformer (VT) Current transformer (CT)
IPrim
Sec
Prim
Sec
PrimVT
N
N
U
Uratio
USec
UPrim
NPrim
NSec
• Rated frequency
• Sweeps, flicker, ferro-
resonance, dips
• Power quality ranges
• Transient impulses
BIL, SIL, chopped,
chopped under SF6
• DC components
| Defined as measuring
range in standard
based on TC38/WG47
Modern Challenges – Frequency Content
Transient phenomena
Continuous phenomena
Compact system installation combined
with GIS-type or conventional SF6 types
- within MHz range (very fast switching operation)
Reduction of secondary loading (3 pol. ferro-
resonance)
- 2nd. sub-harmonics of fundamental frequency fR
High numbers of switching operations
- frequency range from kHz up to MHz
Harmonic waves (keyword „power quality“)
- demands within a frequency range of kHz
Compact network systems
- demands because of proximity effects,
heating, shielding
Reduction of secondary loading (single phase ferro-
resonance)
- demands because of 3rd. or 5th. sub-harmonics of fR
AC/DC or DC/AC converters
Modern Challenges – New phenomena
Modern Challenges – New phenomena
Relevance example: Wind Power in the UK
Wind power boom in the UK, 6th largest producer in the world
Currently 6579 turbines providing over 13 GW, around 10% of UK power
Further growth expected: 2009 Low Carbon Transition Plan (Brown
Ministry) to generate 30% out of renewables by 2020, wind power fastest
growing
Further stress on and increased aging of substation components
What is happening in the grid?
West of Duddon Sands Wind Farm Harestanes Wind Farm
U
t
Disconnector operation:
Voltage at the primary terminal of a
voltage transformer 245 kV
Modern Challenges – New phenomena
U
t
Circuit breaker operation: Voltage at the primary terminal of a voltage transformer 245 kV
Source: Smeets at all; Recent standardization developments and test-experiences in switching inductive load current; CIGRE Nagoya Japan 2015
Modern Challenges – New phenomena
Measurement Technology for the 21st C.
Limitations of conventional instrument transformers
Frequency response of ɛU(f)
Measurement Technology for the 21st C.
PFIFFNER Resistive Capacitive Divider ROF (72-550 kV)
Oil/Paper or SF6 (For GIS)
Protection/Measurement in HV transmission
Measurement of power quality
Highest accuracy from DC up to 10 kHz
Ferroresonance-free and no saturation
effects
Measurement of harmonics up to 1MHz
Florian Gegier
PFIFFNER Instrument Transformers Ltd.
Switzerland
+41 62 739 28 90
Florian.Gegier@pmw.ch
www.pmw.ch
Design of Conventional IT – CT
High voltage terminal
Metallic expension bellows
Composite insulator
Voltage grading
fine-grade low-grade
Current tranformer active part
(sec. windings)
Secondary terminal box
Ground terminal
High voltage terminal
Metallic expansion bellows
Composite insulator
Voltage grading
fine-grade low-grade
Voltage tranformer active part
(prim. and sec. windings)
Secondary terminal box
Ground terminal
Design of Conventional IT – Ind. VT
Design of Conventional IT – Combined
High voltage terminal
Metallic expension bellows
Composite insulator
Voltage grading
fine-grade low-grade
Current tranformer active part
(sec. windings)
Secondary terminal box
Ground terminal
Voltage tranformer active part
(prim. and sec. windings)
Voltage tranformer active part
(prim. and sec. windings)