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Transformer DC Resistance Tester for Large Power Transformers

Name: Transformer DC Resistance Tester for Large Power Transformers
Brand: Xi'an Xu&Hui Electromechanical Technology Co., Ltd.
SKU: XHZ1340A
Price: 4,115.00 USD
Availability: InStock

Product Details:

Place of Origin:	China
Brand Name:	XZH TEST
Certification:	CE/ISO
Model Number:	XHZ1340A

Detail Information

Place of Origin:

China

Brand Name:

XZH TEST

Certification:

CE/ISO

Model Number:

XHZ1340A

Highlight:

High Light

Highlight:

40A High-Current Phase-Separation Testing

Simultaneous High-Low Voltage Connection

Three-Phase Magnetic Assist Degaussing

Trading Information

Minimum Order Quantity:

1 unit

Price:

Negotiable

Packaging Details:

wooden packaging

Delivery Time:

5-8 work days

Payment Terms:

T/T

Supply Ability:

2000unit/year

Product Description

🎯 Target Application: Engineered for ultra-high voltage (UHV) substation commissioning teams and large power transformer testing laboratories handling 330kV–750kV class equipment. Distinct from standard 20A field testers, the XHZ1340A delivers 40A high-current single-phase and 20A+20A three-phase simultaneous output — purpose-designed for the ultra-low resistance windings found in high-MVA power transformers, generator step-up (GSU) units, and interconnection transformers where measurement precision at the micro-ohm level is critical for acceptance testing and post-fault forensic analysis.

XHZ1340A 40A Transformer DC Resistance Tester

The XHZ1340A is a new-generation rapid testing instrument that integrates magnetic assist testing, three-phase simultaneous measurement, and built-in degaussing into a single high-performance platform. Specifically designed for DC resistance measurement of large power transformers — including generator step-up units, UHV interconnection transformers, and high-MVA distribution transformers — it delivers exceptional precision with 0.1µΩ resolution at test currents up to 40A.

XHZ1340A

Key Features

Simultaneous High-Low Voltage Connection: Connect both high-voltage and low-voltage current/potential test leads at once without the need to reverse or reconnect during testing — a unique design that significantly reduces setup time for multi-winding large power transformers.
Three-Phase Simultaneous Testing: Measures A0, B0, and C0 phases concurrently for star-connected windings, reducing total testing duration by over 70% compared to sequential single-phase methods on large transformers.
Automatic Magnetic Assist: Accelerates testing speed for three-phase five-column low-voltage internal corner-connected transformers by pre-saturating the core, particularly effective for the high-inductance windings found in large MVA-rated units.
Neutral Point Measurement Innovation: Proprietary testing sequence that accurately resolves the neutral point lead wire resistance measurement challenge — a long-standing difficulty in three-phase transformer diagnostics.
Comprehensive Data Output: Displays and prints all test results for high, medium, and low voltage windings in a single report. Automatic three-phase unbalance calculation with optional temperature conversion to rated reference values.
Advanced Back-EMF Protection: Safeguards both the instrument and operator during inductive load discharge, enabling safe high-current testing on the largest transformer windings.
Extensive Data Storage: 200 test datasets permanently stored (expandable), with USB export capability for integration with laboratory information management systems and long-term trend analysis.
Field-Rugged Construction: Wide temperature tolerance (-10°C~50°C), shock resistance, anti-interference shielding, and portable form factor (430×320×230mm) designed for both laboratory and substation field deployment.

Technical Specifications

Test Current	Three-Phase: 20A+20A, 10A+10A, 5A+5A, 1A+1A Single-Phase: 40A, 20A, 10A, 5A, 1A, 0.2A
Measurement Range	40A: 100µΩ~0.5Ω \| 20A: 500µΩ~1Ω \| 10A: 1mΩ~2Ω 5A: 10mΩ~4Ω \| 1A: 100mΩ~20Ω \| 0.2A: 1Ω~100Ω 20A+20A: 200µΩ~0.3Ω \| 10A+10A: 500µΩ~0.6Ω 5A+5A: 10mΩ~1.5Ω \| 1A+1A: 100mΩ~7Ω
Resolution	0.1µΩ
Accuracy	±(Reading × 0.2% + 2 words)
Power Supply	AC220V ±10%, 50±1Hz
Dimensions	430 × 320 × 230 mm
Operating Temperature	-10℃ ~ 50℃
Operating Humidity	≤ 85% RH
Data Storage	200 Test Datasets (Expandable via USB)

Frequently Asked Questions

Q1: When should I choose the 40A model over a standard 20A DC resistance tester?

The XHZ1340A's 40A single-phase and 20A+20A three-phase output is specifically designed for large power transformers where winding resistance is extremely low — typically below 500µΩ for high-MVA units. Higher test current improves the signal-to-noise ratio at micro-ohm measurement levels, delivering the 0.1µΩ resolution and ±(0.2%+2 words) accuracy required for acceptance testing of 330kV–750kV class transformers, GSU transformers, and interconnection units. For distribution-class transformers with winding resistance above 1mΩ, the 20A models provide sufficient accuracy.

Q2: How does the simultaneous high-low voltage connection feature improve testing workflow?

Conventional DC resistance testers require sequential connection — test the high-voltage windings, disconnect, then reconnect to the low-voltage side. The XHZ1340A allows all high-voltage (A, B, C, O) and low-voltage (a, b, c, o) test leads to be connected simultaneously at the start of testing. The instrument's intelligent switching matrix automatically routes test current to each winding in sequence without requiring the operator to climb the transformer to change connections. This is particularly valuable for large power transformers where bushing access may require elevated work platforms and each reconnection cycle adds significant time and safety risk.

Q3: How does the instrument solve the neutral point lead wire resistance measurement problem?

In three-phase transformer testing, the resistance of the neutral point lead wire introduces a measurement error that is difficult to isolate. The XHZ1340A employs an innovative testing sequence that mathematically compensates for neutral lead resistance by taking differential measurements across multiple current paths, effectively canceling out the lead wire contribution. This proprietary method provides a true winding resistance value without requiring separate neutral lead calibration — a significant advancement over conventional three-phase testers that typically overestimate resistance when neutral lead resistance is significant.

Q4: Can test results be automatically converted to reference temperature values?

Yes. The XHZ1340A includes a built-in temperature conversion function that automatically calculates resistance values at a specified reference temperature (typically 75℃ for power transformers) based on the measured winding temperature and the conductor material (copper or aluminum). Results can be displayed and printed with both the as-measured and temperature-compensated values side by side. The three-phase unbalance rate is also calculated automatically, and both raw and converted values can be included in the printed test report for compliance with IEC and IEEE acceptance testing standards.

Q5: What degaussing capability does the instrument provide after DC resistance testing?

The XHZ1340A integrates automatic degaussing directly into the test workflow. After completing DC resistance measurements on all windings, the built-in demagnetization function systematically removes residual core magnetism using controlled current attenuation before the transformer is returned to service. This eliminates the need for a separate degaussing instrument and prevents the excitation inrush currents, protection relay maloperation, and sympathetic tripping risks associated with residual magnetism. The degaussing cycle runs automatically as a post-test sequence, and the instrument provides real-time progress indication until complete demagnetization is achieved.

Tags:

Transformer DC Resistance Tester for Large Power Transformers

High Light

Highlight:

40A High-Current Phase-Separation Testing

Simultaneous High-Low Voltage Connection

Three-Phase Magnetic Assist Degaussing

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DC winding resistance tester,

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