Transformer Winding Resistance Ohmmeter/Transformer DC Resistance Tester - Test Precautions and Features?

The test precautions and core features of the transformer DC resistance tester are as follows:

I. Test Precautions

1. Safety First, Thorough Discharge: Before testing, ensure the transformer is completely de-energized and reliably grounded. After testing, the windings will store a large amount of charge. Thorough discharge must be performed using the instrument's discharge function or a dedicated discharge rod before changing the wiring to prevent electric shock.

2. Accurate Temperature Measurement, Result Correction: The actual winding temperature must be accurately measured and recorded during testing. DC resistance values are significantly affected by temperature. All results must be converted to the same reference temperature (e.g., 75℃) for comparison and judgment; otherwise, the data is invalid.

3. Shorten Duration, Reliable Connection: To shorten the current stabilization time of large inductor windings, prioritize instruments with a larger current range or a "fast measurement" mode. The test clamps must have good and secure contact with the transformer terminals to reduce contact resistance.

4. Stabilize Readings, Pay Attention to Balance Rate: Record data only after the instrument reading has completely stabilized. The key focus is on the three-phase resistance imbalance rate, a crucial indicator for diagnosing defects.

II. Core Features

1. Diagnosing Circuit Connection Defects: Effectively detects connection defects in conductive circuits such as poor solder joints in windings, poor contact in tap changers, and inter-turn short circuits, providing a direct means of assessing circuit integrity.

2. High Precision and Rapid Stability: Employs advanced constant current source technology, ensuring stable output current and rapidly bringing the inductor current to a steady state. It also measures resistance at the micro-ohm level with high precision.

3. Anti-interference and Automatic Demagnetization: Possesses anti-power frequency interference capabilities. The advanced instrument automatically demagnetizes the transformer windings after testing, preventing residual magnetism from affecting subsequent operation.

4. Intelligent Calculation and Data Management: Automatically calculates the three-phase imbalance rate and determines if it exceeds limits. Built-in memory facilitates data storage and trend analysis.

Summary: This instrument is a fundamental and crucial tool for inspecting the quality and operating status of transformer windings. Its value lies in its ability to effectively diagnose connection defects in windings and circuits through precise DC resistance measurement. The core operation focuses on safe discharge, accurate temperature conversion, and rapid and stable measurement. MS-520 Transformer DC Resistance Tester

1. The instrument offers 6 output current options, with a maximum current of 20A and a minimum current of <5mA, suitable for measuring the DC resistance of various types of transformers and instrument transformers.

2. The instrument has a wide measurement range (from 100μΩ to 100KΩ).

3. Faster response speed; it can directly switch to on-load tap changer during measurement, and the instrument automatically refreshes the data.

4. The instrument has an audible discharge alarm function, clear discharge indication, and reduces misoperation.

5. Comprehensive protection functions reliably protect against back EMF impacts, ensuring more reliable performance.

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