The CT Tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.

I. Core Testing Functions

1.Turns Ratio Testing

Precisely measures the actual primary-to-secondary current ratio of CTs.

Verifies compliance with nameplate ratings (e.g., 1000A/1A).

Criticality: Incorrect ratios cause metering errors or protection maloperation.

2.Polarity Verification

Determines the relative polarity (dot convention) of primary and secondary windings.

Criticality: Polarity errors may lead to meter reversal, differential protection failure, or false tripping.

3.Excitation Characteristic (V-I Curve) Testing

Plots the excitation current vs. voltage curve (I-V curve) of secondary windings.

Derives key parameters:

Knee-Point Voltage/Current: Identifies CT core saturation threshold.

Accuracy Limit Factor (ALF): Evaluates protection-class CT accuracy under fault currents.

Composite Error: Core performance metric for protection CTs.

Criticality: Determines CT reliability during fault conditions.

4.Winding Resistance Testing (DC)

Measures DC resistance of primary/secondary windings.

Purpose: Detects interturn shorts, poor connections, or conductor defects.

5.Ratio Error & Phase Angle Error Testing

Ratio Error: Percentage deviation between actual and rated ratios (impacts metering accuracy).

Phase Angle Error: Phase shift between primary and secondary currents (affects phase-sensitive devices).

Criticality: Defines metering-class CT accuracy (e.g., Class 0.2, 0.5S).

6.Secondary Burden Testing

Measures total impedance of CT secondary circuits (wires, meters, contacts).

Criticality: Excessive burden causes CT saturation, leading to metering errors or protection failure.

7.Demagnetization Function

Eliminates residual magnetism in CT cores (caused by high currents or DC tests).

Criticality: Remanence alters excitation characteristics, compromising test accuracy.

II. Advanced Features (Modern Smart Devices)

Auto-Calculation & Judgment:

Computes ALF, knee-point, and error limits; outputs "Pass/Fail" verdicts per standards.

Data Storage & Reporting:

Saves results, generates PDF/Excel reports, and enables historical comparisons.

Multi-Function Integration:

Some models support voltage transformer (VT) testing, breaker timing tests, etc.

Portable Design:

Battery-operated handheld units for field use in substations.