Abstract
Partial discharge test and series resonance withstand voltage test are critical items to evaluate the insulation performance of high-voltage electrical equipment such as transformers, GIS, instrument transformers and high-voltage cables during factory delivery, handover and preventive maintenance. Common challenges encountered in field tests include severe partial discharge interference from the power source itself, heavy waveform distortion leading to misjudgment of PD measurement, bulky equipment with difficult transportation and insufficient protection mechanisms that raise test risks.
The 220kV partial-discharge-free variable frequency power supply is tailor-made for high-voltage precision tests. It outputs pure sine waves while delivering high power output and high safety level, serving as the core power supply unit for the complete series resonance and partial discharge test system.
PART 01 Core Product Highlights
Low PD & Pure Sine Wave Output, Good Test Equivalence High-voltage side partial discharge ≤10pC; waveform non-linear distortion ≤1%. It outputs standard sine waves, differing from conventional waveform shaping variable frequency power supplies. No extra peak measurement is required. It eliminates PD interference originating from the power supply itself, ensuring authentic and reliable partial discharge detection data.
Fiber Optic Isolation Communication, Complete Separation of High & Low Voltage Fiber optic communication links the variable frequency power cabinet and control box, fully isolating the high-voltage circuit from the low-voltage control circuit. It prevents risks to personnel and equipment caused by high voltage intrusion into control terminals. Operators can remotely control the equipment, improving safety for on-site tests.
Wide Continuous Adjustable Range, Compatible with Multiple Test Objects Output frequency: continuously adjustable from 30Hz to 300Hz, frequency stability ≤0.05%; Output voltage: continuously adjustable from 0 to 350V, voltage stability ≤1.0%. It flexibly matches capacitive and inductive test objects to complete resonance tuning, induced withstand voltage and other test scenarios.
Full-range Hardware Protection for Secure Testing Integrated with overvoltage, overcurrent, short-circuit, flashover, zero-start, bridge arm fault, power curve protection, fan interlock protection, phase loss protection and more than 10 protection mechanisms. In case of anomalies such as test object breakdown, short-circuit or overload, the equipment rapidly cuts off output to safeguard test personnel, DUT and the whole unit hardware.
Compact Structure, Strong On-site Adaptability Adopts modular design and forced air cooling. Robust cabinet structure suits both laboratory use and mobile field tests. The independent aluminum alloy control box features intuitive human-machine interface, coarse/fine adjustment switching and simple manual resonance tuning. Compared with traditional generator schemes, it boosts on-site work efficiency by 50%.
Product Display
This equipment acts as the power source for the complete test system. It can be matched with excitation transformers, reactors, capacitive voltage dividers and partial discharge detectors to form a full test platform. Applicable Scenarios
Induced withstand voltage and partial discharge tests for power transformers
AC withstand voltage and partial discharge detection for instrument transformers
Withstand voltage tests for GIS, circuit breakers, disconnectors, bushings and insulators
AC withstand voltage tests for high-voltage power cables
Power frequency withstand voltage tests for large generator sets
Power supply for large grounding grid tests
Working Principle
The internal signal source generates standard sine signals, which are amplified to high power via pre-amplifier and bridge power amplifier circuits. The adjustable frequency drives the excitation transformer and reactor. The reactor and the test object form a series resonant circuit to obtain high resonant voltage on the DUT. It can also directly complete transformer induced withstand voltage tests through an intermediate transformer.
PART 03 Key Technical Parameters
| Item | Parameter |
|---|---|
| Input Power | 3-phase AC 380V, 50Hz |
| Rated Output Voltage | 220kV |
| Output Frequency Range | 30Hz ~ 300Hz, continuously adjustable |
| Output Voltage Range | 0 ~ 350V, continuously adjustable |
| Rated Output Current | 0 ~ 7.43A |
| Frequency Stability | ≤0.05% |
| Voltage Stability | ≤1.0% |
| Nonlinear Distortion | ≤1.0% |
| Partial Discharge | ≤10pC (at rated voltage) |
| Operating Condition | -10℃ ~ +40℃, altitude ≤1000m |
| Cooling Method | Forced Air Cooling |
PART 04 Important Notes for On-site Tests
Safety Guidelines for High-voltage Tests
Qualified operators are required for high-voltage tests; set up warning zones and warning signs.
Check test wiring carefully before power-on; ensure reliable grounding of equipment shell.
No wiring adjustment during live test; discharge fully after test.
Prevent high voltage injury; follow standardized operation with safety as priority.
