As the core equipment of the power system, the performance of transformers directly affects the safe and stable operation of the power grid. Transformer tester is a professional equipment used to evaluate the electrical performance, mechanical state, and insulation characteristics of transformers. It is widely used in fields such as power maintenance, manufacturing quality inspection, and scientific research experiments. This article will systematically introduce its classification, working principle, testing standards, and key points of on-site application.

1. Core functions and classification of transformer tester

1.1 Classification by Technical Architecture

-Integrated testing system: integrating multifunctional platform devices (such as OMICRON CPC 100)

-Specialized tester: focusing on a single parameter (such as a variable ratio tester)

-Online monitoring device: real-time monitoring of parameters such as oil temperature and partial discharge

2. Analysis of key testing techniques

2.1 Winding Resistance Test

-Principle: DC voltage drop method (1A-100A constant current source)

-Accuracy requirement: ± (0.2% reading+2 μ Ω)

-Typical fault detection: poor contact of tap changer, short circuit between turns

2.2 Frequency Response Analysis (FRA)

-Sweep frequency range: 10Hz-2MHz

-Characteristic parameters:

-Correlation coefficient (CC)>0.95 (new equipment benchmark)

-Amplitude difference<3dB (warning threshold)

3. On site testing operation specifications

3.1 Preparation before testing

-Safety measures:

-Confirm power outage and ground discharge (>15 minutes)

-Set up a safety fence (during high-voltage testing)

-Environmental requirements:

-Environmental temperature>5 ℃ (oil immersed transformer)

-Relative humidity<80% (to prevent surface leakage)

3.2 Typical testing process (taking 35kV oil transformer as an example)

1. Insulation resistance: 2500V megohmmeter (absorption ratio ≥ 1.3)

2. DC resistance: Testing of tap changer at various levels (unbalance rate<2%)

3. Transformation ratio test: within ± 5% range of rated tap (error<0.5%)

4. No load test: under rated voltage (loss deviation from factory value<10%)

3.3 Key points of data interpretation

-Vertical comparison: comparison with factory data/historical data

-Horizontal comparison: analysis of differences between devices of the same model

-Trend warning: Establish an aging assessment model (if the annual decrease rate of insulation resistance is greater than 20%, a warning is required)

4. Frontiers of Technological Development

4.1 Intelligent Diagnostic Technology

-AI based Fault Pattern Recognition (Convolutional Neural Network Analysis of FRA Graph)

-Digital twin technology for state prediction

4.2 New sensing technology

-Distributed fiber optic temperature measurement (spatial resolution 0.5m)

-Graphene gas sensor (DGA online monitoring)

4.3 Test Automation

-Robot Inspection System (Automatic Connection Test Terminal)

-5G remote expert diagnostic platform

5. Maintenance and management suggestions

5.1 Equipment maintenance cycle

-Daily maintenance: Monthly calibration of measurement accuracy

-Regular maintenance: conduct full functional verification annually

-Software Upgrade: Timely Update Diagnostic Algorithm Library

5.2 Test Data Management

-Establish a database for the entire lifecycle of equipment

-Stored in IEC 61850 standard format

-Linkage analysis with SCADA system data