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Your Professional Transformer DC Winding Resistance Tester Supplier

 

Founded in 1992 and formally incorporated as Wuhan Moen Intelligent Electrical Co., Ltd. on November 12, 2012, with a registered capital of RMB 36 million, we are a professional technology company specializing in the research, development, and production of high-voltage test equipment. Our 8,000 m² facility in Wuhan East Lake High-Tech Development Zone houses dedicated production lines, R&D centers, and administrative facilities. With an experienced technical and production team, Moen focuses on core products including test transformers, series resonance systems, and other high-voltage testing equipment. Backed by years of industry experience, the company is committed to reliable manufacturing, continuous technical improvement, and providing practical solutions for global power utility and industrial customers.

 

 
First 123 Last
 
Why choose us
 

Our Certificate
We are certified in ISO 9001 (Quality), ISO 45001 (Health & Safety), and ISO 14001 (Environment), ensuring high standards in all aspects of our operations.

 

Strong R&D Capability
Committed to technological breakthroughs, including investments to develop 750kV reactor solutions.

 

Experienced Technical Team
A growing team of 61 employees supporting product development, production, and customer service.

 

Complete Pre & After-Sales Service
From solution design and technical support to installation, maintenance, and fast response service.

 

Three-phase DC Resistance Tester

 

Three-phase DC Resistance Tester

Simply put, this is an instrument specifically designed to measure the DC resistance of windings in electrical equipment such as power transformers and switches. It is called “three-phase” because it can simultaneously test the three-phase windings of transformers, greatly improving work efficiency. DC resistance is an important parameter for measuring the conductivity of a coil, which directly affects the heating and energy loss during equipment operation.

 

Three-phase output current test

2* 5 A, 2* 2.5 A, 2* 1 A

Single-phase testing:10A , 5A , 1A

Test range

Three-phase test:2 * 5 A 1 mΩ ~ 1 Ω

2* 2.5A 2 mΩ ～ 2 Ω

2* 1 A 5mΩ～5Ω

Single-phase test

1 0A 50 0μΩ～ 2 Ω

5 A 1 mΩ～ 4 Ω

1 A 5mΩ ～ 20Ω

Resolution

0.1μΩ

Measurement accuracy

±(0.2% of reading + 2 digits)

External dimensions

420mm × 250mm × 340mm

The instrument weighs

15kg

 

Advantages of Three-phase DC Resistance Tester

 

 

High precision testing: This testing instrument has high-precision measurement function, which can accurately measure the winding resistance of transformers and ensure the accuracy of test results.

 
 

Quick testing: Using a three-phase DC resistance tester can quickly perform resistance testing, saving maintenance time and improving work efficiency.

 
 

Portable design: This testing instrument typically has a compact and lightweight design, making it easy to carry and use. It can be tested on-site without the need to move the transformer to the laboratory for testing.

 
 

Multifunctionality: In addition to the resistance testing function, the three-phase DC resistance tester can also perform other transformer maintenance tests, such as grounding resistance testing, transformer ratio testing, etc., providing comprehensive transformer maintenance functions.

 
 

Automated testing: This testing instrument typically has automated testing capabilities, which can automatically record test data and generate test reports, simplifying the testing process and reducing human errors.

 

 

Types Of Three-Phase DC Resistance Tester

High-Current Tester

For large power transformers. Provides three-phase testing up to 20A per phase, with a wide resistance range. Features magnetization, demagnetization, tap-changer testing, and data storage.

 

Medium-Current Tester

For distribution transformers, reactors, and medium motors. Portable, compact, with three-phase testing up to 10A per phase and moderate resistance range.

Low-Current / High-Resolution Tester

For small transformers, instrument transformers, and high-resistance windings. Offers very fine resolution and high accuracy, ideal for manufacturing QC and control windings.

Integrated Multi-Function Tester

Combines DC resistance, turns ratio, polarity, excitation, and sometimes FDS in one device. Reduces the number of instruments needed for factory or field testing.

Portable / Handheld Tester

Ultra-compact, battery-operated, and touchscreen-based. Designed for field crews performing routine tests on many transformers efficiently.

 

Application of Three-phase DC Resistance Tester

 
 
01
 

Factory test of power transformers

Inspect each transformer at the manufacturing plant.

 
02
 

Commissioning test of transformers

Acceptance testing before new equipment is installed and put into operation.

 
03
 

Preventive test (pre-test)

Regular inspections (such as once every 1-3 years), to determine if there are any potential problems with the windings.

 
04
 

Fault diagnosis

When suspecting problems such as inter-turn short circuits, poor contact of leads, or faults in the tap changer, perform measurements for diagnosis.

High Power DC Winding Resistance Tester

 

 
Test Steps Of Three-Phase DC Resistance Tester
 
01/

Safety Preparations

Power off, test for electricity, hang grounding wires, discharge! Ensure that all sides of the transformer are completely isolated and reliably grounded. Remove or disconnect all external connection lines before testing.

02/

Test Wiring

Connect the instrument's current output line (I+) and voltage measurement line (V+) to the top of the A, B, and C phase bushings of the transformer. (For YN connected windings)Connect the corresponding current return line (I-) and voltage measurement line (V-) to the neutral point (O) of the transformer.Ensure all connections are secure and in good contact.

03/

Parameter Settings

Power on, select the appropriate test current (usually the instrument can automatically recommend it), and the type of winding (YN or D, for delta-connected windings, use different methods).

04/

Start Testing

Start the test. The instrument will charge all three-phase windings simultaneously and display the charging current and real-time resistance value changes.

05/

Read The Results

When the resistance value stabilizes (with a change rate less than a certain value), the instrument will automatically lock the data and display the resistance values of A, B, and C phases and their imbalance rates.

06/

Discharge And Line Removal

After the test, do not remove the lines immediately! Wait for the instrument to automatically discharge until the screen shows "Discharge Complete" or the discharge indicator light goes out, then use a discharge rod to fully discharge the windings and finally remove all test lines.

 

Safety considerations

 

Safety first, thorough discharge

Transformer windings are large inductors, storing a huge amount of energy. The "Discharge Complete" displayed by the instrument only indicates the internal energy release. The windings themselves may still have residual voltage. It is necessary to use a dedicated discharge rod for multiple earth discharges to confirm that there is no charge before removing the lines. This is the most important point!

Correct wiring

Always use the four-wire method. The voltage lines (V+, V-) should be on the inner side of the current lines (I+, I-) and directly connected to the winding terminals to avoid including contact resistance.

Eliminate residual magnetic field influence

After multiple consecutive tests or changing the tap position, the residual magnetic field in the iron core will affect the charging speed. The "Demagnetization" function or changing the test polarity can reduce the influence.

Record the ambient temperature

Accurately record the upper oil temperature or winding temperature to facilitate accurate temperature conversion and comparison with the factory values.

 

Test Result Determination of Three-phase DC Resistance Tester
 

Main indicators

The imbalance rate of the three-phase resistance values. Standard requirements: For transformers with a capacity of 1600 kVA and above, the difference between the resistances of each phase winding should not exceed 2% of the average value of the three phases (for transformers without a neutral point lead-out, the difference between phases is not much greater than 1%).

Vertical comparison

The phase resistance or line resistance values measured in this test should not have significant differences compared with the factory values and previous test values (converted to the same temperature).

 

Certificates

 

productcate-400-566
productcate-400-566
productcate-400-566
productcate-400-566

 

FAQ

 

Q: Why does a three-phase DC resistance tester need to consider temperature?

A: The resistance of a conductor varies with temperature, and test data without temperature compensation is not comparable.

Q: How long do I need to wait to read data during testing?

A: Normally, the instrument will automatically complete the magnetization and discharge process and provide stable readings. The specific time depends on the equipment capacity and instrument settings.

Q: If the tested DC resistance value is too high, what could be the reason?

A: Possible reasons include wire aging, poor contact at connection points, internal virtual connections or open circuits, etc.

Q: What is the difference between a three-phase DC resistance tester and a single-phase one?

A: The three-phase tester can test three-phase windings at once, with higher efficiency; Single phase needs to be carried out in stages.

Q: Can it be used to test other equipment besides transformers?

A: In theory, any device with coils, such as motor windings, can be measured using a DC resistance tester.

As one of the most professional transformer dc winding resistance tester manufacturers in China, we're featured by quality products and good price. Please rest assured to buy high quality transformer dc winding resistance tester in stock here and get quotation from our factory. Customized orders are welcome.

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