The KDHG-220P Variable-Frequency Transformer Characteristic Comprehensive Tester is a state-of-the-art instrument specifically designed for the precise and efficient testing of current transformers (CTs) and voltage transformers (PTs). Developed through extensive market research, deep theoretical analysis, and direct feedback from field engineers, this advanced tester meets the evolving demands of modern power systems.

Built on a powerful dual-processor architecture featuring high-performance DSP (Digital Signal Processor) and ARM platforms, the KDHG-220P delivers exceptional stability, enhanced processing speed, and robust reliability. Its fully integrated design ensures comprehensive functionality, high automation, and rapid test execution, significantly improving on-site testing efficiency and accuracy.

The tester supports a wide range of measurement tasks, including excitation characteristics (volt-ampere curve), turns ratio, polarity, secondary winding resistance, burden (load), ratio error, phase angle error, and more—making it ideal for evaluating protection-grade, metering-grade, and transient-performance (TP-class) CTs, as well as electromagnetic units in PTs.

Compliant with international standards such as IEC 60044-1, IEC 60044-6, GB/T 20840.1, GB/T 20840.2, and GB/T 20840.3, the KDHG-220P is engineered for real-world applications. Utilizing advanced low-frequency testing technology, it generates a maximum output of only 180Vrms AC voltage and 12Arms (36A peak) current, yet is capable of accurately testing CTs with knee-point voltages up to 65kV, minimizing risks during high-capacity transformer evaluation.

Equipped with a 5.7-inch transmissive LCD display with excellent visibility even under direct sunlight, the device features a user-friendly Chinese graphical interface and one-button automated testing for key parameters. All results are clearly presented, with automatic calculation of critical CT/PT parameters such as:

• Knee-point voltage/current
• 10% (or 5%) error curves
• Accuracy Limit Factor (ALF)
• Instrument Security Factor (FS)
• Secondary time constant (Ts)
• Remanence coefficient (Kr)
• Saturation and unsaturated inductance

With the ability to store up to 2,000 test records, and support for USB data export to PC, the KDHG-220P enables seamless data management. Integrated software allows for in-depth analysis and automatic generation of editable Word reports, streamlining documentation and compliance.

Weighing less than 9kg and housed in a compact, rugged enclosure (340 × 180 × 330 mm), the KDHG-220P is lightweight and portable—perfect for field testing in substations, power plants, industrial facilities, and commissioning sites.

Main technical features
Comprehensive functionality, meeting the needs of various CT scans (such as...); The excitation characteristics (i.e. volt ampere characteristics), transformation ratio, polarity, secondary winding resistance, secondary load, ratio difference, and angle difference of protection, metering, and TP types can also be used for testing the excitation characteristics, transformation ratio, polarity, secondary winding resistance, etc. of protection PT electromagnetic units.

 

Automatically provide CT and PT parameters such as inflection point voltage/current, 10% (5%) error curve, accuracy limit factor (ALF), instrument safety factor (FS), quadratic time constant (Ts), remanence coefficient (Kr), saturated and unsaturated inductance. ★ It can accurately measure the ratio difference and angle difference, with a maximum allowable error of ± 0.05% for ratio difference and ± 2 minutes for angle difference. It is capable of measuring 0.2S level current transformers, with a ratio measurement range of 1~50000

 

Tested to meet GB20840.1 (IEC60044-1), GB20840.2 (IEC60044-6), GB20840.3, etc

 

Based on the principle of low-frequency testing, it can output a maximum AC voltage of only 180V and an AC current of 12Arms (peak value of 36A), which can cope with CT testing with inflection points up to 65KV.

 

The interface is friendly and beautiful, with a fully Chinese graphical interface.

 

The device can store 2000 sets of test data without loss in case of power failure. After the experiment is completed, use a USB flash drive to store the data on the PC, analyze it using software, and generate a WORD report.

 

5.7-inch graphic transparent LCD, clear and visible under sunlight.

 

The testing is simple and convenient, with one click completion of CT direct resistance, excitation, transformation ratio, and polarity testing. In addition to load testing, all other CT tests use the same wiring method.

 

Easy to carry, device weight<9Kg.

 

Main technical parameters

Test purpose: protective CT, protective PT
Output: 0~180Vrms, 12Anms, 36A (peak)
CT ratio range: 1~30000
CT ratio measurement accuracy: ± 0.05%
PT ratio range: 1~10000
PT ratio measurement accuracy: ± 0.2%
Phase measurement accuracy: ± 2min
Phase measurement resolution: 0.5min
Secondary winding resistance measurement range: 0~300 Ω
Measurement accuracy of secondary winding resistance: 0.2% ± 2m Ω
AC load measurement range: 0~1000VA
Accuracy of AC load measurement: 0.2% ± 0.02VA
Input power supply voltage: AC220V ± 10%, 50Hz
Working environment: Temperature: -10 ℃~50 ℃, Humidity: ≤ 90%
Size and weight: Size 340mm x 180mm x 330mm, weight<9kg