TRAX
Transformer & Substation Test System
Joacim Sköldin
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Transformer – “The electric gear box”
Fixed ratio, e.g. 100 kV / 10 kV
LTC (Load Tap Changer)
• 100±9x1.67% / 10 kV
DETC (De-Energized Tap Changer)
• Tuning voltage level
• Change configuration, e.g. from Dzn10 to
Yzn11
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Basic transformer model (impedance)
Primary side:
• Winding resistance,
• Leakage Inductance
(X1+(N1/N2)2*X2)
• Magnetization current
(excitation current)
Secondary side
• Winding resistance
• Inductance
Primary to secondary
• Turn ratio (E1/E2)
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Measuring the parameters
Excitation/magnetization
current (field) and no-load
loss (factory) measurements
Winding resistance
measurements (factory and
field)
Load-loss measurements
(factory)
Short-circuit impedance
(voltage) measurements
(factory and field)
Turn ratio (factory and field)
R+jX = R1+jX1 + (N1/N2)2 x (R2+jX2)
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Summary - Impedance
modeling
The ideal transformer combined with the
simple equivalent circuit describes the
physics of the transformer well.
The important measurement parameters
are:
Magnetization/Excitation current
(voltage dependent)
Winding resistance (temperature
dependent)
Short-circuit impedance/Leakage
reactance
Turns ratio
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Guides and standards for transformer testing
Most standards (IEC and ANSI/IEEE) are focusing on
new transformers and factory testing
IEC 60076
IEC 60076-…
IEC 60076-18 SFRA
IEEE
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Guides and technical brochures for
transformer FIELD testing
Workgroups in Cigré have over the years produced a lot of
Technical Brochures (TB) e.g. on sweep frequency
response measurements (TB342), partial discharge
(TB444), dielectric response measurements (TB414) etc
IEEE 62-1995 is probably the most well-known guide for
diagnostic field testing of oil filled power transformers. The
guide today belong to the IEEE C57-series and last
published revision is C57.152-2013
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Cigré Technical Brochure
445, 2011
Guide for Transformer
Maintenance
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CIGRE TB 445
Cigré TB 445, ”Guide for Transformer Maintenance”,
was published 2011
TB 445 is a comprehensive combination of education
handbook, thesaurus and a guide for transformer
maintenance including guidelines for how to perform
measurements in the field
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Section 5.1 Electrical
Measurements
Methods for
On-Site
Transformer
Diagnosis
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Diagnostic Technique
Basic Electrical
Advanced Electrical
Dissolved Gas Analysis (DGA)
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Basic Electrical
Winding Ratio
Winding Resistance
Magnetization current
Capacitance and DF/PF
Insulation Resistance
Core Ground Test
- TRAX, TTR
- TRAX, MTO
- TRAX, Delta, TTR
- TRAX, Delta
- MIT
- MIT
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Advanced Electrical
Frequency Response of Stray Losses (FRSL)
Frequency Response Analysis
Polarization/Depolarization
Frequency Domain Spectroscopy
Recovery Voltage Method
Electrical Detection of PD
Acoustical Detection of PD
UHF Detection of PD
- TRAX
- FRAX
- IDAX
- IDAX
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Summary CIGRE TB 445
TB 445 is a combination of a transformer handbook,
thesaurus and application guide for transformer
maintenance including guidelines for transformer
field testing
Lots of very good information. Details and guidelines
can and will be discussed e.g. assessment data and
advantages/disadvantages with different
measurement methods (e.g. combined PDC-FDS
combination versus true AC DFR/FDS
measurements)
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TRAX – Overview
Multi-function test system for transformer and substation testing
State-of-art winding resistance and tap-changer testing functionality
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100A @ 50V compliance
Adaptive demagnetization
Tap-changer control
Dynamic resistance measurements
High voltage ratio measurement (250 V and 2200 V output)
3-phase circuit-breaker analyzer
Optional switchbox for 3-phase/6-winding measurements
Optional unit for insulation testing
CT and VT testing
And much more...
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Target Markets
OEMs - High performance
Service companies - < 32 kg shipping
Utilities - Multi-function unit for substation testing
Power intensive industries - Toolbox for a lot of electrical tests
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TRAX Strategy - Simplicity
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Simplicity challenge…
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TRAX - Target Applications
Power transformer testing
CT and VT testing
Substation testing
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Circuit-breaker
Single-phase relay
Ground/earth
Multi-purpose…
Generators and motors
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Technical Overview
- Generators and outputs
Current generators
• 100 A DC
• 20 A AC
• 800 (200) A AC
Voltage generators
• 2200 V AC
• 250 V AC
• 300 V DC
Binary
• 2 contacts for tap-changer and circuit-breaker operation with
internal voltage and current measurement
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Technical Overview
- Measurements
Measurement channels
• Internal current and voltage measurements on test signal
outputs
• 4 x multi-purpose voltage/current measurements
• 2 x DC voltage measurements
• 1 x transducer input for motion transducer, Rogowski coils etc
Binary inputs
• 3 x dry/wet contacts for relay and circuit-breaker timing (main
and resistor)
• 1 x trig input
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Technical Overview
- Accessories
Optional switchbox for 3-phase/6-w winding resistance, turns ratio,
magnetic balance, excitation current, short-circuit impedance etc
Optional 12 kV tan delta/power factor testing
Optional 2000 A current output for primary testing
Optional 17 kV tan delta/power factor testing (generators and
motors)
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Technical Overview
- Instruments/Apps
Standard transformer
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Winding resistance
OLTC continuity
Demagnetization
Turns ratio
Excitation current
Short-circuit impedance
(leakage reactance)
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Technical Overview
- Instruments/Apps)
Advanced transformer
• OLTC DRM and dynamic
current (“ripple”)
• Frequency Response of Stray
Losses (FRSL)
• Magnetic balance
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Technical Overview
- Instruments/Apps
Manual Control
• Generators
– Manual control
– Set values
– Ramp
• External and internal measurement channels
• Calculated parameters
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Resistance
Impedance
Reactance
Power
VA
Phase
Inductance
Capacitance
Arithmetics
Customer defined
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Technical Overview –
Instruments/Apps)
CT/VT testing
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CT excitation
Winding resistance
CT demagnetization
Current ratio
Voltage ratio
CT Rogowski
CT/VT low power/electronic
Burden
Voltage withstand
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Technical Overview
- Instruments/Apps)
Substation
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CB analyzer
LV CB
Relay
Timer
Phase-angle meter
Ground/earth/impedance
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Key Features & Benefits
Intelligent simplicity
Intuitive and easy to use
Short-time learning process
Easy to expand and upgrade
State-of-the-art WRM and OLTC
capabilities
Fast and repeatable tests on all
transformer configurations and sizes
Seven channel digital multimeter
4 + 3 analog external measurement
channels offers unmatched capabilities
3 phase circuit breaker analyzer
Timing, motion, coil current, station voltage
Weight <32 kg in transport case
Can be shipped as check-in luggage
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