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: Before testing, ensure the transformer is completely de-energized and grounded on both high and low voltage sides. After testing, the windings will store charge; ensure they are fully discharged before changing wiring to prevent electric shock.

2. Accurate Temperature Measurement: Record the winding temperature during testing (approximately the top oil temperature). The result must be converted to a reference temperature (e.g., 75℃) for comparison; otherwise, the data is invalid.

3. Rapid Measurement: Select a high current range or an instrument with a "rapid measurement" function to shorten charging time and reduce winding heating.

4. Reliable Connection: The test clamps must make good contact with the transformer terminals to reduce contact resistance. Record readings only after the readings have stabilized completely.

II. Core Features

1. Precise Diagnosis: Effectively detects defects in the conductive circuit, such as poor tap changer contact, loose winding solder joints, and inter-turn short circuits.

2. High Efficiency and Precision: Utilizes constant current source technology to quickly reach steady state, enabling precise measurement of resistance at the micro-ohm level.

3. Intelligent Protection: Possesses anti-interference capabilities; advanced instruments feature automatic demagnetization to eliminate residual magnetism in the windings.

4. Automatic Analysis: Automatically calculates the three-phase resistance imbalance rate and determines if it exceeds the standard; built-in memory facilitates data analysis.

Summary: This instrument is a key tool for inspecting transformer winding quality and can effectively diagnose circuit connection defects. Key operational steps include safe discharge, accurate temperature conversion, and reliable connection to ensure accurate and efficient testing.

The MS-520S Transformer DC Resistance Tester achieves simultaneous three-phase power application, independent current and voltage sampling, and simultaneous measurement and display of three-phase resistance values and three-phase imbalance rate, significantly shortening the transformer DC resistance testing time and solving the problem of long testing times for DC resistance of various tap windings in power transformers.

1. The instrument can select the appropriate output current value for testing based on the tested object, primarily suitable for measuring the inductive resistance of transformers, instrument transformers, etc.

2. For large transformers with a five-limb core and a delta-connected low-voltage winding, the instrument can use a high-low voltage series excitation method for testing. The instrument automatically connects the winding's auxiliary magnetizing circuit internally, enabling rapid and accurate testing of the DC resistance of the low-voltage winding.
3. The instrument has a three-channel testing function to complete three-phase DC resistance measurement with a single connection for star-connected windings, automatically calculating the three-phase imbalance rate, greatly saving measurement time and improving work efficiency. It can also use a phase-by-phase testing function to perform phase-by-phase testing on transformers with YN or D(Y) connections until the test is complete.

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