Product introduction
A Variable Frequency Series Resonant AC Withstand Voltage Test System (also known as a Frequency-Tuned Series Resonant Test System or VFSR) is critical equipment in the power industry used for performing power-frequency AC withstand voltage tests on large-capacity, high-voltage electrical equipment such as power cables, GIS, transformers, generators, switchgear, etc.
The Variable Frequency Resonant Test Set ingeniously utilizes the principle of LC series resonance to overcome the drawbacks of traditional power-frequency withstand voltage test equipment (power-frequency test transformers), such as excessive bulkiness and extremely high capacity requirements when testing large capacitive loads.
Technical Parameters
| Rated output voltage | 0～1000kV and below |
| output frequency | 30～300Hz |
| Resonance voltage waveform | Pure sine wave, waveform distortion rate≤1.0% |
| Working time | Full power continuous working time of 60min |
| Quality factor | 30~90 |
| Frequency regulation sensitivity | 0.1Hz |
| Instability | ＜0.05% |
| Working power supply | Single-phase 220V or three-phase 380V±10% |
| Power frequency 50Hz±5% |
Serial product configuration(Application range (10kV ~ 500kV voltage grade substation electrical equipment ac withstand voltage equipment, frequency 30 ~ 300Hz))
| Product model name | Variable frequency source | Resonant reactor | Exciter transformer | Voltage divider | Scope of application |
| UHV-50/50 | 4kW | 25kV/1A two(dry) | 4kVA(dry) | 50kV | 1000kVA and below 10kV power transformer. 10kV switch , bus, PT, CT, etc. 10 kv (300mm2) cable 1.0 km or less |
| UHV-108/108 | 6kW | 27kV/1A four(dry) | 6kVA(dry) | 110kV | 31500kVA and below 35kV power transformer. 35kV switch , bus, PT, CT, etc. 10 kv (300 mm2)cable≤2km.35kV (300mm2)cable≤0.5km |
| UHV-200/200 | 10kW | 50kV/1A four(dry) | 10kVA(dry) | 200kV | 50000kVA and below 110kV power transformer.110kVGIS,PT,CT etc.(Preventive test).35kV(300mm2)cable≤1.0km.10kV (300mm2)cable≤2.0km |
| UHV-270/270 | 15kW | 45kV/1A Six sets of(dry) | 15kVA(dry) | 300kV | 50000kVA and below 110kV power transformer.110kVGIS,PT,CT etc..35kV(300mm2)cable≤1.2km.10kV (300mm2)cable≤3.0km |
| UHV-800/400 | 30kW | 50kV/2A eight(dry); 100kV/2A four(oil-immersed) |
30kVA(dry); 30kVA(oil-immersed) |
400kV | 80000kVA and below 220kV power transformer.50000kVA and below 110kV power transformer.110kV/220kVGIS,PT,CT etc..35kV(300mm2)cable≤2.0km.110kV (300mm2)cable≤0.7km |
| UHV-1600/800 | 60kW | 200kV/2A four(oil-immersed) | 60kVA(dry) | 800kV | 220kV power transformer of 80000kVA and below.50000kVA and below 110kV power transformer.500kVGIS,PT,CT etc..220kV switch ,GIS,PT,CT etc..110kV(400mm2)cable≤1.5km.220kV (400mm2)cable≤1.0km |
Main Advantages
1.Compact Size and Light Weight: The power source only needs to supply the active power required for resonance (overcoming circuit resistive losses) and the excitation voltage (Uin). Its required capacity is only about 1/Q of the EUT's reactive capacity. Compared to traditional test transformers needing to supply the full reactive power, the equipment size and weight are drastically reduced, making it highly suitable for field testing.
2.High-Quality Test Voltage Waveform: Outputs a near-pure sinusoidal waveform, complying with standard requirements.
3.High Safety:
If the EUT breaks down, the resonance condition collapses, automatically limiting the short-circuit current (to just the excitation current), preventing damaging high fault currents.
Sensitive and reliable overvoltage protection.
4.Large Test Capacity: Theoretically, capacity can be scaled up by adding reactors or increasing the Q-factor to meet the requirements of larger capacitance, higher voltage EUTs.
5.High Test Accuracy: The voltage divider directly measures the high-voltage side, ensuring high precision.
6.High Degree of Automation: Automatic frequency sweep/resonance finding, automatic voltage ramp-up, automatic timing, automatic protection, data logging.
FAQs
What type of variable frequency power supply is used?
UHV uses advanced variable frequency power supplies featuring:
IGBT inverter technology
Digital frequency control
Stable output performance
High efficiency
Energy-saving operation
What types of reactors are available?
Depending on the application, we can provide:
Dry-type reactors
Epoxy-cast reactors
High-insulation reactors
These reactors are built for long service life and dependable operation.
What are the advantages of series resonance compared with traditional AC hipot testing?
Series resonance offers several benefits:
Lower power consumption
Higher testing efficiency
Smaller power source requirements
Better performance with large capacitive loads
Improved safety if a breakdown occurs
This is why it is widely used for cable and GIS testing.
Is the system suitable for field testing?
Yes.
The modular design makes transportation and installation much easier.
Benefits include:
Lightweight modules
Flexible configuration
Fast on-site setup
Easy maintenance
The system is widely used in substations and field testing projects.
Can the system be expanded later?
Yes.
Additional reactors, voltage dividers, and control modules can be added if future projects require higher voltage levels or larger test capacities.
Can UHV customize the system?
Absolutely.
We can customize:
Voltage levels
Test capacities
Frequency ranges
Mobile test systems
Containerized high-voltage laboratories
Integrated testing platforms
Each solution is designed around the customer's specific requirements.
What installation and training services do you provide?
UHV provides:
On-site installation support
Commissioning services
Operator training
Technical documentation
Acceptance test assistance
Our engineers make sure the system is fully operational before handover.
Do you provide test reports and calibration certificates?
Yes.
We can supply:
Factory test reports
Calibration reports
Traceable calibration certificates
Optional third-party calibration services
These documents help support quality audits and compliance requirements.
What software functions are available?
Optional software features include:
Real-time monitoring
Data acquisition
Historical data storage
Automatic report generation
Data export
User access management
How are test reports generated?
The software automatically generates reports after testing.
Reports can be exported in:
PDF format
Excel format
Customer-specific formats
This makes documentation and record keeping much easier.
What maintenance is required?
Routine maintenance is simple and mainly includes:
Cleaning system components
Checking electrical connections
Verifying protection functions
Performing periodic calibration
The system is designed for long-term operation with minimal maintenance.
What after-sales support does UHV offer?
We provide long-term support throughout the life of the equipment, including:
Technical consultation
Remote troubleshooting
Software updates
Spare parts supply
Preventive maintenance advice
Operator training
Ongoing technical support
Our goal is to help customers keep their systems running reliably and get the most value from their investment.
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