I. Core Application Scenarios
The application of the transformer comprehensive tester runs throughout the entire lifecycle of the transformer, and the main scenarios are as follows:
Production verification: The transformer manufacturer uses it for factory inspection to ensure product quality.
Acceptance and commissioning: Power companies and large industrial enterprises conduct acceptance tests before installing the transformer to ensure that the performance meets the standard requirements.
Operation and maintenance: On-site personnel in substations and power plants conduct regular preventive tests and fault diagnosis on running transformers to ensure the safe operation of the power grid, such as testing high inflection point voltage transformers like transformer bushings CT and generator outlet CT.
II. Main Test Items
Excitation characteristic (voltage-current characteristic) test: Draw saturation curves, calculate inflection point voltage/current, which is the core item for evaluating the performance of protective CT.
Transformation ratio and polarity test: Verify whether the transformer’s transformation ratio and winding connection direction are accurate.
Ratio difference and phase difference test: Evaluate the metering accuracy of the transformer, especially important metering points.
10%/5% error curve calculation： Determine whether the protective CT can meet the reliability requirements for protection device action in fault conditions.
Winding DC resistance test： Check whether there are welding defects or poor contact problems inside the winding.
Secondary load test： Measure the actual load of the secondary circuit to confirm whether it is within the rated capacity of the transformer.
III. Core Principles and Steps for Selection
The core of selecting the transformer comprehensive tester is to match the actual requirements. The following four steps can be followed：
Step 1： Clearly define the object being tested and the testing requirements.
Object type： Determine whether to mainly test CT， PT， or both， and confirm whether it involves special types such as bushing CT， GIS internal CT， or transient CT of TP type.
Core items： When it is mainly for protection CT acceptance， the excitation characteristic and 10% error curve are the core functions； when it is mainly for关口 metering， the test accuracy of ratio difference and phase difference is the primary consideration.
Key parameters： Record the larger rated current/voltage of the tested transformer， accuracy class (such as 0.2S， 5P20)， and rated capacity as the basis for selecting the instrument range.
Step 2： Match key performance indicators
Output voltage and current： During excitation testing， the instrument’s larger output voltage should be higher than the inflection point voltage of the tested CT. For protective CT， the inflection point voltage can reach hundreds to thousands of volts， so the corresponding output voltage model should be selected； during transformation ratio testing， the instrument’s larger output current should meet the requirements for the strength of the test signal.
Test accuracy： The equipment accuracy usually needs to be two to three accuracy classes higher than that of the tested transformer. For example， when calibrating 0.2-class transformers， it is recommended to use a calibration instrument with an accuracy of no less than 0.05%.
Function integration： For on-site operations， priority should be given to selecting a multi-functional comprehensive tester to reduce the number of equipment carrying and wiring； for specialized research in the laboratory， a more specialized equipment can be selected.
Step 3： Consider usage scenarios and convenience
Portability： When used on-site， the focus should be on the weight and volume of the equipment. Currently， the mainstream portable comprehensive testers have a weight ranging from 8kg to 23kg.
Operation experience： Check if it is equipped with a large screen， a rotating mouse， or a touch screen for human-computer interaction interfaces.
Data management： Confirm whether the equipment supports data storage， USB export， and whether it can directly generate test reports in Word/Excel format， facilitating later data organization and analysis.
Step 4： Examine technology and service guarantees
Choose products with mature technology and good market reputation.
Confirm that they can provide timely and effective technical support and maintenance services.
Post time: Mar-16-2026