IEC 61869 Automatic Demagnetization One-click Current Transformer Tester

IEC 61869 Automatic Demagnetization One-click Current Transformer Tester

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In substation handover acceptance, annual preventative maintenance, and upgrade projects worldwide, the following situations frequently arise during the maintenance of current transformers and voltage transformers :

1. Traditional split-system testing methods require multiple instruments, with a complete test of a single CT taking 2-3 hours, resulting in low on-site efficiency.

2. Older protective CT cores have significant residual magnetism. Ordinary testing instruments lack built-in demagnetization and hysteresis loop testing functions, posing a safety hazard of malfunctioning or failing to operate protection relays.

3. Field engineers easily confuse electromagnetic PTs with capacitive CVTs; misuse of testing modes can directly cause permanent hardware damage to the testing equipment.

4. Relying on manual data recording results in a huge workload of documentation; pass/fail determination according to IEC 60044-1 relies entirely on operator experience, leading to a high risk of human error.

5. When testing multi-winding CTs, forgetting to short-circuit unused secondary windings will directly cause data distortion.

Typical Field Application Scenarios

★Note: The following are demonstrations of typical operating conditions in the power industry, used to showcase the capabilities of the GDVA-405 equipment, and are not records of specific real customer projects.

Demonstration Scenario｜110kV Substation Handover & Preventive Testing

Condition: A 110kV substation, configured with approximately 42 sets of current transformers, 16 sets of electromagnetic voltage transformers, including both protection-grade and metering-grade CTs.

Previous Pain Points:

• Using multiple discrete instruments to complete the full set of CT tests, a complete test of a single protection CT takes 2-3 hours;

• Testing the residual magnetic interference inflection point voltage of the protection CT core, the lack of built-in demagnetization causes a 10% error curve inaccurate results;

• Manual judgment of results based on IEC standards is required, and manually compiling Word reports is a large workload.

Advantages of the GDVA-405 Current Transformer Tester:

Functions

• Multi-International Standard Automatic Evaluation:Three evaluation modes: Evaluation off, workload-only evaluation, and rated + workload dual-condition evaluation. Automatically determines the current transformer's pass/fail status based on IEC and ANSI standards, highlighting unqualified items in red.

• Intelligent Nameplate Calculation:When the nameplate is lost or worn and illegible, the instrument automatically calculates the primary and secondary rated currents and accuracy class based on winding resistance, inflection point voltage, and measured turns ratio.

• Excitation Curve Comparison Function:Historically archived excitation curves can be retrieved and compared on the same screen for intuitive assessment of the current transformer core aging and deterioration.

• Multi-View Test Results Viewing:Displays hysteresis loop, excitation data table, excitation curve, error curve, turns ratio phase error, winding resistance, secondary load, and evaluation parameters across multiple pages.

• Data Storage and Export:Stores thousands of test records locally; export raw data files and Word format test reports to a USB drive; report headers and footers can be customized.

• Two Selectable Test Modes:Standard test mode and quick test mode.

• Safety shutdown logic: The software executes the shutdown process and the screen prompts that the discharge is complete before disconnecting the wiring is allowed to prevent residual high voltage from injuring test personnel.

FAQ:
●Q₁: The CT excitation test curve is distorted, and the inflection point identification is inaccurate. What are the reasons?

●A: ① The CT core has a large amount of residual magnetism. Please use the standard test mode; the instrument will perform two automatic demagnetization cycles. The fast mode does not have a complete demagnetization process, and CTs with high residual magnetism should not be used. 

② For multi-winding CTs, the remaining windings are not short-circuited. Idle secondary windings must be reliably short-circuited. 

③ The measurement wiring position is incorrect. The voltage measurement line needs to be connected inside the power output terminal to eliminate errors caused by contact resistance. 

④ The CT primary side is not disconnected from the high-voltage bus, causing induced noise interference in the measurement. The primary power connection must be disconnected.

●Q₂: Can the GDVA-405 test CVT capacitive voltage transformers?

●A: No. The ratio and phase error function of this instrument is only for electromagnetic PTs. CVTs have an internal capacitive voltage divider structure, and the test principle is incompatible. The test results will be invalid and may damage the equipment. CVTs must be tested using a dedicated CVT analyzer.

Q₃: If the instrument's "automatic nameplate calculation" result is worn on the transformer nameplate, can it be directly included in the official report?

A: Nameplate calculation is an auxiliary reference function, derived from measured data. For critical protection-level CTs, try to refer to the original manufacturer's documentation; it is not recommended to rely entirely on the automatic calculation result to issue an official report.