EN
DRM-20S Three-Phase DC Winding Resistance Meter
DRM-20S Digital Intelligent Three-Phase DC Resistance Tester (20A Max Current) with Magnetic Assist Technology, Three-Channel Synchronous Sampling, Auto Demagnetization, Yn/Y/Δ Winding Support, Automatic Three-Phase Unbalance Calculation, 7-inch Touch Screen, for 110kV/220kV Large Power Transformer Winding DC Resistance Test.
- Description
- Specifications
- Applications
- Advantages
- FAQ
- Recommended Products
Description
The DRM-20S is a professional, high-performance three-phase DC resistance test instrumentexclusively designed for fast and accurate measurement of winding resistance in large power transformers. It fully complies with DL/T 845.3-2019 and GB 50150-2016 standards, adopting advanced magnetic assist charging technology and three-channel synchronous sampling to achieve ultra-fast test speed, which is 3 times faster than traditional single-phase testers.
The instrument features a 7-inch high-resolution color touch screen and intuitive graphical interface, supporting one-time wiring to complete all test items for Yn, Y and Δ type windings. It has a built-in magnetic assist circuit that significantly reduces the charging time of large inductive loads, and an automatic demagnetization function to eliminate residual magnetism in transformer cores after testing. Equipped with a comprehensive back-EMF protection system, it ensures operator and equipment safety. It also supports automatic three-phase unbalance calculation, 500 groups of data storage, and USB data export. Ideal for factory acceptance tests (FAT), on-site commissioning tests and preventive maintenance tests of 110kV/220kV large power transformers, especially on-load tap-changing transformers.
Specifications
| Parameter | Specification |
|---|---|
| Maximum Output Current | 20A per channel |
| Current Gears | 1mA, 10mA, 100mA, 1A, 5A, 20A (auto/manual selection) |
| Measurement Range | 20A: 0.5mΩ – 100mΩ 10A: 1.0mΩ – 300mΩ 5A: 10mΩ – 1.0Ω 1A: 200mΩ – 6.0Ω 100mA: 2.0Ω – 60Ω ≤10mA: 30Ω – 50kΩ |
| Resolution | 0.1μΩ |
| Accuracy | ±0.2% of reading ± 2 digits (full range) |
| Measurement Method | 4-wire Kelvin measurement |
| Stabilization Time | ≤2 seconds |
| Supported Winding Types | Yn, Y, Δ |
| Magnetic Assist Technology | Yes |
| Automatic Demagnetization | Yes |
| Three-Phase Unbalance Calculation | Yes |
| On-Load Tap Changer Test Mode | Yes |
| Temperature Conversion | Copper (20℃/75℃), Aluminum (20℃/75℃) automatic conversion |
| Data Storage | 500 groups (with time stamp, power-off protection) |
| Data Export | USB interface, PDF/Excel report generation |
| Display | 7-inch high-resolution color touch screen |
| Power Supply | AC 220V±10%, 50Hz (optional built-in lithium battery) |
| Protection Functions | Back-EMF protection, Over-current protection, Over-temperature protection, Short-circuit protection, Interlock protection |
| Dimensions (mm) | 420×350×180 (L×W×H) |
| Weight | ~8kg (including carrying case) |
| Operating Temperature | -10℃ ~ +50℃ |
| Operating Humidity | ≤90%RH (non-condensing) |
| Altitude | ≤2000m |
| Compliance | DL/T 845.3-2019, GB 50150-2016, IEC 60076-1:2022, IEC 60404-2:2008 |
Applications
Core Test Objects
- Large power transformers: 110kV/220kV oil-immersed power transformers (up to 240MVA)
- On-load tap-changing transformers: transformers with on-load tap changers (OLTC)
- Distribution transformers: 10kV/35kV oil-immersed and dry-type distribution transformers
- Electric motors: large synchronous motors and induction motors
- Instrument transformers: current transformer (CT) and voltage transformer (VT) winding test
- Reactors: shunt reactors and series reactors
Typical Usage Scenarios
- Transformer manufacturing plants: factory acceptance tests (FAT) of large power transformers
- Power companies: on-site commissioning tests and preventive maintenance tests
- Third-party testing laboratories: compliance testing and certification
- Power plants: generator transformer and auxiliary transformer tests
- Mining and industrial enterprises: large transformer inspection and maintenance
Advantages
Compliance with International Standards
Fully meets DL/T 845.3-2019, GB 50150-2016 and IEC 60076-1 standards → test results are globally recognized
Three-Channel Synchronous Test
One-time wiring completes all three-phase tests → improves test efficiency by 300%, reduces labor cost and test time
Magnetic Assist Technology
Significantly reduces charging time of large inductive loads → test time for 220kV transformer windings is reduced from 30 minutes to 5 minutes
Automatic Demagnetization Function
Eliminates residual magnetism in transformer cores → prevents transformer core saturation and no-load loss increase
On-Load Tap Changer Test Mode
No need to discharge between tap changes → greatly improves test efficiency of on-load tap-changing transformers
Automatic Three-Phase Unbalance Calculation
Automatically calculates unbalance rate and judges pass/fail → eliminates manual calculation errors
Comprehensive Safety Protection
Multiple protection layers + back-EMF protection → maximum safety for operators and expensive test equipment
User-Friendly Touch Screen Interface
7-inch color touch screen with intuitive graphical interface → easy to operate, reduces operator skill requirements
FAQ
Q: What is the difference between DRM-20S three-phase tester and DRM-10W single-phase tester?
A:
- DRM-20S (Three-Phase): Three-channel synchronous test, one-time wiring completes all three-phase tests, magnetic assist technology, automatic demagnetization, on-load tap changer test mode, optimized for 110kV/220kV large power transformers
- DRM-10W (Single-Phase): Single-channel test, built-in battery, portable design, optimized for 10kV/35kV distribution transformers and on-site testing Both use 4-wire Kelvin measurement and have the same measurement accuracy.
Q: What is magnetic assist technology and what are its advantages?
A: Magnetic assist technology uses an additional magnetic field to accelerate the saturation of the transformer core during DC resistance testing, significantly reducing the charging time of large inductive loads. For 220kV transformer windings, the charging time is reduced from 30 minutes to 5 minutes, greatly improving test efficiency.
Q: Why is automatic demagnetization important?
A: DC resistance testing will leave residual magnetism in the transformer core, which can cause core saturation, increase no-load loss and noise, and even damage the transformer. The automatic demagnetization function eliminates residual magnetism after testing, ensuring the normal operation of the transformer.
Q: Can DRM-20S test Δ type windings?
A: Yes. It supports Yn, Y and Δ type windings. For Δ type windings, it uses a special test algorithm to accurately measure the phase resistance without changing the wiring.
Q: Does it support on-load tap changer test?
A: Yes. It has a dedicated on-load tap changer test mode. You can directly switch taps during the test without discharging the transformer, which greatly improves the test efficiency of on-load tap-changing transformers.
