Transformer characteristic tester, commonly known as volt-ampere characteristic tester or CT/PT comprehensive tester



It is the core equipment in the power system for detecting the performance of current transformers (CT) and voltage transformers (PT), directly related to whether the relay protection device can operate correctly and the accuracy of energy metering. In the context of 2025-2026 technology, this equipment has evolved from a single "volt-ampere characteristic test" to a fully automatic, multifunctional, high-precision comprehensive diagnostic platform. 1. Core test objects and functions This instrument is mainly used for electromagnetic transformers (not applicable to the capacitive voltage divider part of capacitive voltage transformers CVT, but can test their electromagnetic units). A. Current Transformer (CT) Test Volt-ampere characteristic (excitation characteristic): Core function. Measure the excitation current and voltage relationship curve of the secondary winding, calculate the saturation point and knee point voltage. This is the key to determining whether the CT will saturate under short-circuit current, causing protection refusal. Transformation ratio test: Automatically measure the actual transformation ratio, check whether it is consistent with the nameplate. Polarity check: Automatically judge the P1/P2 direction to prevent wiring errors that may cause protection misoperation. Secondary winding DC resistance: Measure coil resistance, evaluate wire quality and contact condition. Demagnetization: Automatically perform demagnetization operation to eliminate the influence of core residual magnetism on accuracy (residual magnetism can cause CT saturation in advance). Ratio error and phase error: High-precision measurement of ratio error and phase error, used for calibration of metering CTs. Transient characteristics (TPY/TPZ class): High-end models can simulate transient processes, test the transient coefficient of protection CTs (