High‑voltage cables and insulating materials are core fundamental components in power systems, new energy, rail transit and aerospace. Their insulation and withstand voltage performance directly determine the operational safety and service life of power equipment. Withstand voltage testing constitutes a mandatory item throughout R&D, production, factory inspection and O&M maintenance, including power‑frequency withstand test, DC withstand test, lightning impulse test, partial discharge (PD) test and breakdown voltage test. It verifies insulation capability, voltage endurance and aging life, serving as the critical detection method ensuring power system safety. The high‑voltage power supply is the core of withstand voltage test systems, delivering stable, high‑precision and wide‑range high‑voltage output. Its wide boosting capability, output stability, breakdown protection response speed and PD suppression performance define test accuracy, repeatability and operational safety, forming the key performance bottleneck of high‑voltage insulation testing equipment.
Withstand voltage testing for high‑voltage cables and insulating materials imposes extremely stringent requirements beyond conventional industrial power supplies: 1.Ultra‑wide boosting & ultra‑high stability: Tests for low‑voltage insulation require hundreds of volts, while UHV cables and special insulating materials demand up to 100 kV~1000 kV continuously adjustable output. Long‑term voltage stability ≤±0.2%/1 h and ripple ≤0.5% are mandatory to avoid deviation in performance evaluation. 2.Ultra‑fast breakdown protection: Upon insulation breakdown during testing, the power supply must cut off high voltage within 1 μs and suppress short‑circuit current to prevent sample burnout, equipment damage and safety accidents. Complete voltage/current waveform recording at breakdown is required for failure analysis. 3.Extremely low partial discharge: For PD testing, inherent equipment PD shall not exceed ≤10 pC to avoid interference with sample detection and ensure authentic test results. 4.Wide capacitive load adaptability: Load capacitance varies from several pF to several μF, covering small insulation samples and long large‑capacitance cables. Stable operation from no‑load to short‑circuit with adjustable boosting speed is essential. 5.Full standard compliance: Designs must fully comply with national and international high‑voltage test standards in terms of procedure accuracy, protection logic and traceable data, satisfying type approval and grid access certification. Conventional power‑frequency test transformers and traditional high‑voltage supplies suffer from narrow boosting range, slow breakdown response, high inherent PD and difficulty charging large capacitive loads. All designs strictly follow GB/T 16927.1‑2011, GB/T 16927.2‑2013, GB/T 3048.8‑2007, GB/T 1408.1‑2006 and IEC 60060 series to meet high‑precision, high‑safety and standardized testing demands for power industries and material R&D.
This methodology establishes a full‑process technical framework covering wide‑range boosting topology, high‑precision voltage regulation, ultra‑fast breakdown protection, low PD optimization, insulation test scenario adaptation and comprehensive safety protection. It supports power‑frequency withstand, DC withstand, breakdown and partial discharge testing for power cables and electrical insulation components, providing standardized design guidelines for localization and performance upgrading of domestic high‑voltage insulation testing equipment.
Targeting wide‑range boosting, microsecond breakdown protection, ultra‑low PD and high‑stability output, the main architecture adopts precision front‑end regulation + high‑frequency resonant inversion + modular cascaded voltage multiplication + full‑hardware breakdown protection, integrated with low‑PD structural design and adaptive boosting algorithms. It achieves 0~1000 kV continuous adjustable output, ≤1 μs breakdown response and inherent PD ≤10 pC, fully complying with global high‑voltage insulation test standards. Five core design principles are defined.
1.Specialized wide‑range low‑PD high‑stability topology: Two independent topological systems cover integrated AC & DC testing. The DC withstand framework adopts four stages: digital linear regulation + full‑bridge LLC resonant inversion + cascaded symmetrical voltage multiplication. The front‑end precision linear stage delivers ultra‑stable DC input with fluctuation ≤±0.05%, eliminating grid interference and enabling fine voltage tuning. The intermediate LLC stage operates at 20 kHz~100 kHz with full ZVS/ZCS soft switching across all loads, removing hard‑switch spikes, noise and induced PD; fixed‑frequency control guarantees output stability ≤±0.1%. The rear cascaded symmetrical voltage multiplier achieves up to 1000 kV by stacking modular units, equally distributing voltage stress, reducing insulation difficulty, lowering ripple and suppressing partial discharge. Constant‑current charging mode is embedded for large capacitive cable loads to solve slow boosting and inrush current issues. The AC power‑frequency withstand topology adopts digital frequency conversion + linear power amplification + low‑PD high‑voltage transformer, generating 0~500 kV / 45~65 Hz standard sine waves with THD ≤1%. High‑precision DDS ensures frequency accuracy ≤±0.01 Hz and amplitude accuracy ≤±0.1%. Linear amplification eliminates switching noise and PD. The low‑PD power‑frequency transformer adopts vacuum oil‑immersed or SF6 gas insulation with optimized winding shielding and uniform electric field distribution, achieving inherent PD ≤5 pC for authentic partial discharge testing. Modular integration realizes combined DC, power‑frequency and impulse testing for complete type approval requirements.
2.Wide‑range high‑precision regulation & adaptive boosting control: A dual closed‑loop fully digital framework based on DSP+FPGA ensures high accuracy across the full voltage range. FPGA executes ≥200 kHz high‑speed sampling, PWM modulation and hardware protection; DSP manages algorithms, boosting logic, test sequencing and data communication. 24‑bit high‑precision ADC with ≥100 kHz synchronous sampling guarantees real‑time signal fidelity. The outer adaptive PID voltage loop maintains overall accuracy ≤±0.2% FS, linear regulation ≤±0.1% and load regulation ≤±0.2%. The inner deadbeat predictive current loop suppresses current surges and enables constant‑current charging for large capacitive loads. Three seamless boosting modes (constant voltage, constant current, constant slew rate) fully comply with GB/T 16927.1 standardized procedures: steady holding during withstand testing, controlled charging for cables, and fixed kV/s linear rise to prevent misjudgment of insulation failure. Built‑in current limiting, automatic hold timing and auto ramp‑down complete full testing cycles without manual intervention.
3.Ultra‑fast breakdown protection & fault suppression mechanism: A four‑stage protection system including high‑speed detection, instantaneous cutoff, current suppression and high‑fidelity waveform recording realizes ≤1 μs breakdown response. Dual hardware detection utilizes two independent high‑speed comparators: one monitors di/dt with response ≤100 ns; the other detects sudden voltage drop within ≤1 μs. Either trigger activates protection to capture both hard and soft breakdown instantly. FPGA 1 MHz waveform sampling with wavelet feature recognition distinguishes capacitive charging current, leakage current and true breakdown current, preventing false triggering and identifying pre‑breakdown early warnings. Dual redundant cutoff immediately blocks drive signals and disconnects the high‑voltage loop via solid‑state switches within 1 μs. An active discharge circuit reduces residual high voltage to safe levels within 50 μs, while non‑inductive current limiting suppresses surge energy to protect samples and hardware. High‑speed 10 MHz waveform sampling records 100 ms pre‑breakdown and 100 ms post‑breakdown data, automatically locking breakdown voltage with ≤±0.2% precision. All test data are stored for over 10 years with traceable standardized reports satisfying certification and factory inspection requirements.
4.Three‑level ultra‑low partial discharge optimization: Source suppression, structural optimization and shielding isolation ensure inherent PD ≤10 pC. Soft‑switch ZVS/ZCS eliminates voltage spikes and corona discharge; optimized drive dv/dt and di/dt reduce high‑frequency noise. All high‑voltage components adopt low‑PD specifications including low‑noise rectifiers and low‑partial‑discharge polypropylene capacitors. Sharp edges are eliminated through smooth electric field transition. Full 3D finite‑element electric field simulation optimizes all high‑voltage structures, keeping maximum field strength 30% below PD inception level with sufficient insulation margin. Oil‑immersed transformers adopt high‑vacuum degassing; SF6 insulated units achieve uniform internal fields; voltage multiplier modules use vacuum potting with bubble‑free epoxy resin to eliminate internal air gaps. Double‑layer shielding with aluminum inner enclosure and grounded external shielding room provides full electromagnetic isolation; optical isolation separates low‑voltage control from high‑voltage sections; multi‑stage EMI filtering blocks conducted interference; low‑PD coaxial output cables avoid radiation coupling during PD testing.
5.Insulation test adaptation & full standard compliance: Embedded standardized test templates fully aligned with GB/T 16927, GB/T 3048, GB/T 1408 and IEC 60060 support one‑click power‑frequency, DC, breakdown, PD and aging testing with automatic boosting, holding and ramp‑down flows. Custom editable parameters enable tailored testing for special materials and cable models. Multi‑channel synchronous testing improves efficiency while maintaining independent protection per channel. Synchronous triggering interfaces integrate PD detectors, dielectric loss analyzers and environmental chambers for comprehensive material performance evaluation. Long‑term aging testing supports hundreds of hours of continuous operation with power‑off resume functionality for lifetime evaluation. All measurement systems adopt traceable high‑voltage dividers with measurement uncertainty ≤±1%; test reports fully satisfy type approval, certification and third‑party calibration requirements.
Core optimizations focus on wide‑range boosting, intelligent breakdown identification and low‑PD enhancement: Constant‑current adaptive charging ensures linear controllable slew rates from 0.1 kV/s to 10 kV/s for large cable loads; soft pre‑charging eliminates inrush current; capacitive current compensation accurately separates true leakage current from charging current to avoid misprotection; multi‑module synchronous voltage sharing guarantees stable ultra‑high‑voltage output without localized overheating or PD. Machine learning enhanced breakdown classification identifies hard breakdown, soft breakdown, pre‑breakdown and partial failure patterns to improve protection accuracy and enable early failure warning for aging evaluation. Graded protection strategies apply warning, current limiting, voltage reduction and emergency shutdown according to leakage characteristics, balancing sample protection and test completeness. Electric field simulation and component screening minimize inherent PD; full factory aging and PD screening eliminate defective units; optimized star grounding prevents ground loop interference and ensures reliable shielding for authentic partial discharge measurement.
Full‑lifecycle reliability and comprehensive safety protection serve as fundamental constraints: All critical components adopt Grade‑I over‑rating with voltage stress ≤50%, current stress ≤40% and temperature stress ≤60% to extend service life. Every high‑voltage component undergoes strict PD, thermal cycling and high‑voltage aging screening to eliminate early failures. System MTBF ≥30,000 hours supports long‑term laboratory and on‑site operation. Embedded self‑diagnosis provides health monitoring, calibration reminders and predictive maintenance; modular design ensures MTTR ≤30 minutes. A 15‑level dual hardware/software redundant protection system covers over/under voltage, overcurrent, short‑circuit, breakdown ultra‑fast trip, overtemperature, door interlock, emergency stop, zero‑start prohibition, over‑time withstand protection, leakage limit, insulation monitoring and system fault diagnosis; all hardware protection responds within ≤1 μs. Zero‑voltage startup prevents high‑voltage inrush; high‑voltage chamber interlocks cut output instantly when doors open; dual normally‑wired emergency stops activate rapid discharge for personnel safety; real‑time insulation monitoring prevents leakage hazards. Full compliance with IEC 60060 and GB 4793.1‑2020 ensures qualified clearance, creepage distance, EMC and electrical safety with complete documentation for certification and industrial deployment.
In summary, this integrated framework resolves traditional limitations including narrow boosting range, slow breakdown response, high inherent PD and poor large‑capacitance charging performance. The cascaded modular topology achieves 0~1000 kV fully adjustable output; dual hardware breakdown detection delivers ≤1 μs protection; the three‑stage low‑PD design ensures inherent PD ≤10 pC in full compliance with international high‑voltage test standards. Widely applicable to power cables, transformers, instrument transformers and surge arresters, it covers withstand, breakdown and partial discharge testing, delivering core technological support for domestic substitution and high‑end upgrading of Chinese high‑voltage insulation testing equipment.