Transformer DC Resistance Tester
The ZW8320 and ZW5320 are new-generation diagnostic instruments designed for the rapid and highly accurate measurement of transformer DC resistance.
Featuring true 3-phase simultaneous testing, automatic unbalance calculation, and smart degaussing functions, they significantly reduce testing time during transformer manufacturing, installation, and preventive maintenance.
Product Overview
Transformer DC resistance measurement is a mandatory test to detect manufacturing defects such as loose connections, broken strands, and poor welding.
The tester utilizes advanced microprocessor control and a high-resolution 7-inch touch screen to deliver an intuitive and fast testing experience. With a maximum current output of 20A, these testers easily handle both semi-finished and finished large-capacity transformers in harsh substation environments.
Functions and Value:
1. True 3-Phase Testing: Capable of simultaneously testing Yn, Y, and Δ type windings without requiring operators to manually switch cables. The system automatically calculates the 3-phase unbalance rate, drastically reducing on-site working time.
2. Auto Degaussing Function: Built-in demagnetization eliminates transformer residual magnetism after testing, preventing dangerous inrush currents when the transformer is re-energized.
3. Saturable Magnetic Circuit Method (ZW8320 only): By applying magnetic assistance, the ZW8320 drastically accelerates the testing speed of low-voltage (LV) high-current windings on large power transformers.
4. Data Stability Tracking: Automatically calculates the resistance change rate within 5s, 15s, and 30s. This helps engineers easily judge data stability and prevents misreading during standard tests.
5. Comprehensive Protections: Engineered with robust safety features, including protection against back electromotive force (EMF), accidental disconnection, bad grounding, and misconnection to 380V AC power.
6. Smart Data Management: Features a built-in thermal printer for instant reports, internal storage for 200 data sets, and a USB interface for mass storage export via a FAT/FAT32 flash drive.
Technical Details
| Parameter | Specification |
|---|---|
| Models | ZW5320 |
| Output Current (Single Phase) | 20A, 10A, 5A, 1A, 0.1A |
| Output Current (Three Phase) | 10A+10A, 5A+5A, 1A+1A, 0.1A+0.1A |
| Measurement Range | 0.5mΩ ~ 200Ω |
| Accuracy | ±(0.2% of reading + 2 digits) |
| Display | 7-inch industrial capacitive touch screen |
| Power Supply | AC 220V ±10%, 50/60Hz |
| Additional Functions | USB Export, Thermal Printer, Auto Degaussing |
| Operating Temp | -10℃ ~ 50℃ |
| Dimension | 400mm × 315mm × 223mm |
| Weight | Approx. 9 kg |
Model Selection Guide
| Feature | ZW5320 | ZW8320 |
|---|---|---|
| Max Output Current | 20A | 20A |
| Max Resistance Range | Up to 200Ω | Up to 25kΩ (Includes 10mA, <1mA steps) |
| 3-Phase Auto Test | Supported | Supported |
| Auto Degaussing | Supported | Supported |
| Magnetic Assist | Not available | Supported |
| Best Application | Standard distribution & medium power transformers. | Large power transformers requiring rapid LV winding tests. |
Recent Work
Parts List
| Item NO. | Max Current | Measuring Range | Main Features | Recommended Application |
|---|---|---|---|---|
| GDZR-10A | 10A | 100μΩ - 20KΩ | Portable, built-in discharge alarm | Small to medium distribution transformers |
| GDZR-20A | 20A | 10μΩ - 10KΩ | High-speed testing, heat dissipation | Medium-sized power transformers |
| GDZR-40A | 40A | 1μΩ - 2KΩ | Dual-channel measurement, high current | Large-scale power transformers |
| GDZR-40A | Three-Phase 10A | 100μΩ - 10KΩ | Three-phase simultaneous measurement | Yn-type transformers, time-saving |
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Frequently Asked Questions
Contact our engineers for technical support and application guidance.
While both models offer 20A output and 3-phase simultaneous testing, the ZW8320 includes a Saturable Magnetic Circuit Method (Magnetic Assistance) and an extended measurement range up to . This makes the ZW8320 exceptionally fast and accurate when testing the low-voltage windings of large-capacity power transformers.
DC resistance testing leaves residual magnetism in the transformer core. If not removed, this can cause massive inrush currents when the transformer is put back online. The auto degaussing function safely neutralizes this magnetism with a single click.
Yes. For Yn, Y, and type windings, the tester measures all three phases simultaneously (without reconnecting cables) and automatically calculates the unbalance rate on the screen, saving significant on-site time.
Absolute safety is built-in. The testers are equipped with advanced discharge circuits and multiple protections against back electromotive force (EMF), accidental disconnections, and bad grounding, ensuring both operator and equipment safety.
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