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TRAXTransformer & 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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� 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

Guides and technical brochures for transformer FIELD testing

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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 ElectricalMeasurements 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 - TRAX, TTR� Winding Resistance - TRAX, MTO� Magnetization current - TRAX, Delta, TTR� Capacitance and DF/PF - TRAX, Delta� Insulation Resistance - MIT� Core Ground Test - MIT

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Advanced Electrical

� Frequency Response of Stray Losses (FRSL) - TRAX� Frequency Response Analysis - FRAX� Polarization/Depolarization - IDAX� Frequency Domain Spectroscopy - IDAX� Recovery Voltage Method� Electrical Detection of PD� Acoustical Detection of PD� UHF Detection of PD

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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

• 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

• 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• 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

– Resistance– Impedance– Reactance– Power– VA– Phase– Inductance– Capacitance– Arithmetics– Customer defined

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Technical Overview –Instruments/Apps)

� CT/VT testing• 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• CB analyzer• LV CB• Relay• Timer• Phase-angle meter• Ground/earth/impedance

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Intelligent simplicity Intuitive and easy to use Short-time learning processEasy to expand and upgrade

State-of-the-art WRM and OLTC capabilities

Fast and repeatable tests on all transformer configurations and sizes

Weight <32 kg in transport case Can be shipped as check-in luggage

Seven channel digital multimeter 4 + 3 analog external measurementchannels offers unmatched capabilities

3 phase circuit breaker analyzer Timing, motion, coil current, station voltage

Key Features & Benefits