Transformer testing equipment for large photovoltaic power plants

The large photovoltaic plants where solar power begins require transformers to step up the voltage for distribution once the DC voltage coming out of the photovoltaic systems has been converted to AC voltage. As the U.S. plans to add 54.5 gigawatts of new utility-scale electric-generating capacity to the power grid in 2023, and the new minimum level performance requirements set in 2016 by the US Department of Energy for higher efficiency distribution transformers, there is a demand for transformer testing capabilities to keep up. The solution is the HAEFELY DTTS Distribution Transformer Test System, which allows for induced voltage testing and extremely accurate loss measurements. Applied voltage testing, partial discharge testing, winding resistance, turns ratio, and insulation resistance testing can be added optionally for enhanced testing procedures. The DTTS allows for a high testing throughput in conformity with IEEE C57.12.90, without compromising quality. This system has been designed to allow fast automated test procedures with minimal manual intervention, avoiding human errors.

DTTS Features
  • Models available for 3 phase transformer testing up to 5,000 kVA
  • State of the art frequency converter (up to 200 Hz)
  • Powerful operating software with intuitive interface and automated test sequences
  • The highest accuracy and the only completely calibrated and certified measurement system
  • The lowest system noise level allowing highly sensitive partial discharge measurements
  • Integrates all routine tests within one unique system
  • Reduced testing time
  • Plug and Play
  • Centralized controlling and reporting
  • Easy integration into existing production lines
  • Excellent stability, symmetry, and THD parameters for enhanced accuracy

HAEFELY also offers the SPTTS Power Transformer Test System (Small Power Transformer Test Set) designed for routine testing of power transformers. The SPTTS is a multifunctional tool, including all routine tests within one unique system. The SPTTS can be expanded further to include winding resistance, turns ratio, insulation resistance, partial discharge, capacitance and tan delta, and on-load tap changer testing.

SPTTS Features
  • State of the art frequency converter (up to 200 Hz)
  • The highest accuracy and completely calibrated and certified measurement system
  • The lowest system noise level allowing highly sensitive partial discharge measurements
  • Integrates all routine tests within one unique system
  • Fulfills all IEC and IEEE/ANSI standards
  • Free adjustable test frequency up to 200 Hz
  • Low life-cycle costs and low maintenance
  • Excellent stability, symmetry, and THD parameters for enhanced accuracy
  • Modular design for futures expansions

For additional power and distribution transformer measurements, particularly for on-site tests, HAEFELY/Tettex has created a quick and reliable combination for a complete transformer test solution. The MIDAS Micro 2883 and the 2293 Winding Analyzer are compact, lightweight, and rugged. Combine them or use them separately for various testing applications.

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WA 2293 Features

  • Multipurpose Winding Analyzer: transformer winding resistance, turns ratio, vector-group detection, arbitrary phase ratio, demagnetization, magnetic balance, dynamic resistance, short circuit impedance, and heat run test (heat rise and cooling curve) all in one instrument
  • 7″ touch screen interface with full graphical test visualization
  • Advanced procedure for turns ratio and phase displacement measurement (also on arbitrary phase shifted transformers)
  • Demagnetization function
  • Tap changer control signal
  • Data transfer over USB memory-stick or LAN
  • Setup made easy – simple “one-time-connection” system: once connected will test all phases on both windings
  • Unique simultaneous winding magnetization method for winding resistance measurements, equivalent to traditional equipment with up to 100 A test current.
MIDAS micro 2883 Features
  • Shortest measuring time for power factor, dissipation factor (tan delta), and capacitance
  • Compact, one-box design (25 kg / 55 lbs)
  • 7″ color touch screen for easy operation
  • 12 kV high voltage source
  • Variable frequency range of 15 – 400 Hz
  • Accuracy of 0.3% (capacitance) and 1×10-4 (tan delta)
  • Safe operation with interlock, emergency stop, safety checks and HV ground surveillance
  • Three operating modes: basic, guided, advanced
  • Rugged case with included accessories bag
  • Highest accuracy
  • Advanced interference suppression
  • Ability to measure tan delta of insulating oil quickly on site with the 6835 Portable Oil Test Cell

An important step in testing transformers is to be sure the transformer has the correct primary to secondary turns ratio. The rugged and portable 2796 Fully Automated 3 Phase 250 V Transformer Turns Ratio Meter is ideal for acceptance testing and on-site maintenance testing of transformers. The TTR 2796 helps to ensure there are no faulty transformer windings, such as open windings, improper winding connections, and shortened turns, as well as defective tap changer positions.

TTR 2796 Features
  • Fully automated measurement of turns ratio, voltage ratio, phase displacement, and excitation current.
  • Highest measurement accuracy in the industry of up to 0.03% for ratios 0.8 – 100
  • Better transformer excitation due to higher test voltage of 250 V
  • Ratios of up to 50,000 can be measured
  • Measurement of phase displacement of transformers with irregular vector groups, such as phase shifting, arc-furnace, and traction transformers
  • Simplistic user interface for quick test setup
  • Color-coded and labeled test leads for easy setup
  • Safety connection control feature that proofs test setup before applying regular test voltage to guarantee safety of the test personnel and instrument
  • Automatic winding connection identification (AWCI) and automatic vector group detection supports the quick and easy operation
  • Remote control via laptop and application software, including automatic report generation
  • Built-in printer for quick test report generation
  • Lightweight, compact and rugged design for use in harsh environments

Detection of displacements such as winding movements and mechanical failures due to mechanical shock, transportation, or short circuits can reduce unplanned delays in installations or maintenance costs, and the detection of displacements can possibly improve the system’s reliability by preventing outages. The FRA 5311 Sweep Frequency Response Analyzer detects these failures and is the smallest and lightest device in the industry and very easy to use.

FRA 5311 Features
  • Measures according to IEC 60076-18 and IEEE C57.149
  • Measures magnitude (dB), phase angle (°), impedance (Ω), admittance (S), and ratio
  • High signal to noise ratio due to output voltage up to 11 Vppat 50 Ω
  • IEC 60076-18 Appendix E XML file format compatible to import, export, and share test results with other devices
  • Rugged, lightweight, and smallest SFRA instrument on the market
  • One single USB connection for data and power to a laptop
  • Windows based, easy to use graphical interface, including analysis mode for curves comparison and automatic reporting capabilities
  • Predefined test sequences for most common transformers

Partial discharge testing is an important quality assurance test that can be conducted on transformers in the factory following manufacturing. The DDX 9160 Portable PD & RIV Detector and DDX 9161 PD & RIV Detector are the newest fully digital and state-of-the-art PD detectors from HAEFELY!

Choose between a battery-operated (DDX 9160) or laboratory-optimized (DDX 9161) version. These highly versatile detectors can accommodate up to four simultaneous PD/RIV and Voltage channels as well as internal measuring impedances to reduce the number of external components within the PD circuit.

DDX 9160 & DDX 9161 Features

  • DDX 9160 Portable PD detector operated by battery or 12 V power supply. Ideal for testing power transformers using the bushing tap method.
  • DDX 9161 Laboratory-optimized PD detector is ideal for testing distribution transformers using the capacitive coupling method.
  • AC and DC measuring modes
  • User defined measuring band
  • Modular design, 1 to 4 channels, and capability to daisy chain many detectors
  • Simultaneous RIV and PD reading
  • Phase Resolved PD (PRPD) patterns for fingerprinting
  • High-resolution spectrum analyzer with oscilloscope
  • Data acquisition and test report generation
  • Optically decoupled from the computer
  • Unit can be easily upgraded (up to 12 simultaneous PD/RIV readings)
  • Reduce the number of required components and save space by utilizing an internal integrated measuring impedance, or external AKV 9360 measuring impedance and combining with the 9231 Series(AC) or 9241/100/1 (AC & DC) coupling capacitors (all components housed in the base of the divider)

Transformers are designed to be in operation for 40 years or longer. Insulating oil is a decisive criterion for reliable operation. The thermal, electrical, chemical, and mechanical degradation processes that occur essentially determines the quality of the insulating oil, and hence, the lifetime of the transformer. Using BAUR dielectric strength oil testers, it’s like having an expert by your side, being able to test the oil before extensive and catastrophic failures happen, and ensuring the reliability of your transformer.

BAUR Dielectric Strength Oil Tester Features
  • Measurement technology and power electronics designed for exceptionally long service life
  • High quality glass test vessels with incorporated micrometer for easy setting of the electrode distance
  • Precise, reliable, and reproducible measurement results over very long periods
  • Insulating oil dielectric strength testing according to ASTM D877, ASTM D1816, and many more
  • Models capable of measuring the dielectric breakdown voltage up to 100 kV
  • Repeatable, reproducible breakdown measurements of mineral, silicone, and ester oils

Further precise analysis and diagnosis of insulating oils can be achieved with the DTL C Power Factor / Tan Delta Oil Tester. This combines the measurement of dissipation/power factor, specific resistivity, and relative permittivity all in a single instrument.

DTL C Features
  • Fully automatic measurement of tan delta / power factor, specific resistivity, and relative permittivity of insulating oils
  • Maximum accuracy with tan delta measurement up to 1×10-6
  • Measurement of the specific resistance with both polarities up to 100 TΩm
  • 12 pre-programmed fully automatic test standards, including ASTM D924, ASTM D1169, IEC 60247, and IEC 61620
  • Fast and precise induction heating of the test cell with accurate temperature control for a temperature independent result
  • High quality test cell — in accordance to IEC 60247
  • Automatic draining of the test cell without disassembling

Proper cable diagnostic testing and the efficient location of cable faults are additional areas that photovoltaic plants have to be aware of. Read our blog on top-of-the-line cable testing and diagnostic solutions as well as cable fault location solutions.

Are you interested in transformer testing solutions?

Whether you want to learn more or would like a quote, contact us.

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