HNBPXZ-2000kVA/500kV Variable Frequency Resonance Test System: Transformer Testing Equipment Gains International Recognition
Recently, a delegation representing Bangladesh's power sector visited Goldhome for an inspection tour and conducted factory acceptance testing on the procured HNBPXZ-2000kVA/500kV variable frequency resonance test system. The company's General Manager and technical team warmly received the distinguished visitors. Both parties engaged in in-depth discussions regarding the equipment's technical specifications, application scenarios, and future collaboration opportunities. The successful completion of this acceptance process signifies that Guodian Huamei's technical capabilities in the transformer testing equipment sector have once again gained international market recognition.
Within the product exhibition hall and high-voltage testing facility, the Bangladeshi delegation conducted comprehensive factory acceptance testing on the HNBPXZ-2000kVA/500kV variable frequency resonant test set scheduled for export. This equipment represents Guodian Huamei's core product, specifically engineered for AC withstand voltage testing of large transformers (oil-immersed and gas-insulated transformers) and high-voltage electrical equipment such as GIS.
During the equipment assembly phase, engineers demonstrated the combination connection of reactors on-site. To meet testing requirements for the 500kV voltage level, multiple high-voltage reactors were connected using a 'parallel-then-series' configuration. While operating the system, the engineer explained: 'The reactors employ dry epoxy resin vacuum casting technology, delivering excellent interlayer insulation properties. Each reactor achieves a quality factor (Q-value) exceeding 40. Through varied series-parallel combinations, we can accommodate test specimens across different voltage ratings and capacitances.'
During system commissioning, the engineer activated the variable-frequency control cabinet, initiating automatic frequency sweeping. The touchscreen interface displayed real-time frequency, voltage, current, and Q-factor curves. Within 35 seconds, the system automatically located the resonance point at 148.7Hz and maintained stable test voltage output. The technical lead of the client delegation meticulously verified the on-screen data, expressing satisfaction with the speed and precision of the automatic tuning.
During the withstand voltage demonstration, engineers set the test voltage to 500kV and the withstand time to 1 minute, adhering to IEC 60060 and GB/T 16927 standards. Upon pressing the 'Start' button, the voltage steadily rose to the set value, exhibiting a stable waveform without distortion, while leakage current monitoring remained within normal parameters. Members of the client delegation closely monitored the instrumentation throughout, periodically capturing key data with cameras. After one minute, the equipment automatically de-energised to zero, concluding the test successfully.
Verification of protective functions constituted a critical acceptance phase. Engineers simulated a flashover fault on the test specimen, prompting the equipment to automatically interrupt high-voltage output within milliseconds while triggering audible and visual alarms. The client repeatedly confirmed the device's overvoltage, overcurrent, and flashover protection capabilities, expressing high praise for its safety performance.
Core Components and Operating Principles
The apparatus comprises four principal sections:
- Frequency Conversion Control Cabinet: Converts 380V mains power into adjustable sinusoidal waveforms of variable frequency and voltage, supplying the entire system. Employing a DSP+FPGA architecture, it achieves frequency resolution down to 0.01Hz.
- Excitation Transformer: Boosts the voltage from the variable-frequency power supply to the appropriate test voltage, matching the resonant circuit.
- High-Voltage Reactor Bank: The core component of the resonant circuit. Multiple reactors can be used in parallel or series to meet different voltage level requirements.
- Capacitive Voltage Divider: Continuously measures the resonant voltage across the test specimen and generates overvoltage protection signals.
As a National High-Tech Enterprise, Goldhome has specialised in high-voltage testing since its establishment in 2008. With over 10,000 square metres of factory space, the company holds more than 45 patented technologies and over 10 software copyrights. The company has evolved into a nationally renowned manufacturer of high-voltage power testing equipment and provider of testing services. Within the series resonant technology sector, its product portfolio encompasses three major series: power frequency series resonant, frequency-modulated series resonant, and variable inductance series resonant. Covering voltage levels from 10kV to 1000kV, these solutions meet testing requirements across industries including power systems, rail transit, petrochemicals, and metallurgical mining. In 2025, the company secured multiple patents including one for high-voltage divider installation structures, further consolidating its technological leadership.
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