What is the working principle of the high-voltage switch dynamic characteristic tester?

The high-voltage switch dynamic characteristic tester uses multi physical quantity synchronous acquisition and high-speed signal processing technology to capture the mechanical motion and electrical characteristics of the switch opening and closing process in real time, generate time stroke curves, and calculate key parameters. Its working principle can be decomposed into four core links: data acquisition, signal processing, parameter calculation, and result output. The following is a specific analysis:

1. Data collection: Multi sensor collaborative sensing

The tester synchronously collects the switch motion status and electrical characteristics through four types of sensors: displacement sensor, acceleration sensor, opening and closing coil current sensor, and auxiliary contact signal

① Displacement sensor (core)

Type: Linear grating ruler (accuracy ± 0.01mm), rotary encoder (accuracy ± 0.1 °), or laser ranging module.

Function: Real time measurement of the travel of the moving contact, generating a travel time curve (for example, a 550kV circuit breaker with a total travel of 120mm needs to be opened within 10ms).

Application scenarios: Calculate the speed of just opening/closing (average speed before and after 10ms of contact separation/contact), overtravel (additional travel after complete contact of the contact).

② Acceleration sensor (auxiliary verification)

Type: Piezoelectric accelerometer (range ± 500g).

Function: Calculate the stroke through secondary integration, cross validate with displacement sensor data, and eliminate sensor installation errors (such as compensating for tilt angles greater than 5 °).

③ Opening and closing coil current sensor

Type: Hall current sensor (accuracy ± 0.5%).

Function: Monitor changes in electromagnetic force of the operating mechanism, identify faults such as iron core jamming and coil disconnection (such as a plateau period in the coil current waveform, indicating insufficient energy storage).

④ Auxiliary contact signal

Function: As a time reference point, mark the actual opening and closing time of the moving contact, and correct the delay error of the travel sensor (such as using digital filtering algorithm to eliminate mechanical contact shaking ≤ 3ms).

2. Signal Processing: High speed Sampling and Anti interference Design

The tester needs to complete signal conditioning, digitization, and synchronization within a millisecond time window to ensure data integrity

① High speed sampling module

Sampling rate: ≥ 1MHz (1 data point collected per microsecond), capturing transient processes such as contact bounce (period 2-5ms).

Resolution: 16 bit ADC (minimum resolvable voltage change 0.15mV), adapted to different sensor outputs (such as grating ruler output 0-5V analog signal).

② Anti interference technology

Hardware isolation: Sensor signals are isolated by optocouplers (such as 6N137), with a withstand voltage of ≥ 5kV, to block high-voltage electric field interference.

Software filtering: FIR digital filter (cut-off frequency 10kHz) is used to filter out electromagnetic pulse noise generated during switch operation.

Grounding design: The tester housing forms a single point grounding with the ground to avoid interference introduced by the grounding loop (during on-site testing, it is necessary to ensure that the grounding resistance is less than 4 Ω).

3. Parameter calculation: extraction of key performance indicators

Based on the collected data, the tester calculates the following core parameters through algorithms:

① Time parameter

Opening and closing time: the duration from coil energization to contact separation/contact (e.g. vacuum circuit breaker closing time ≤ 80ms).

Different periodicity: maximum time difference between three-phase/fracture (national standard requires ≤ 2ms, ultra-high voltage equipment requires ≤ 1ms).

Bounce time: The duration of oscillation before the first stable contact after contact separation (e.g. bounce time ≤ 5ms for oil circuit breakers).

② Speed parameter

Initial opening/closing speed: the average speed within 10ms before and after the contact separation/contact.

Maximum speed: the extreme slope of the travel time curve.

③ Travel parameters

Total travel: The displacement of the contact from the open position to the closed position.

Overtravel: The compression stroke of the buffer after the contact of the contact.

4. Result output: Visualization and diagnostic recommendations

The tester presents the calculation results in a graphical interface and report format to assist users in quickly determining the switch status:

① Waveform display

Travel time curve: visually display the movement trajectory of the contact, mark the just open/close point and bounce area.

Coil current curve: Analyze the electromagnetic attraction characteristics.

② Parameter report

Automatically generate detection reports that comply with DL/T 846 standards, including all calculated parameters and deviation rates from standard values.

③ Fault diagnosis

Built in expert system, providing fault causes based on abnormal parameter combinations.

5. Technical difficulties and solutions

① Reproduction of high-speed motion trajectory

Challenge: When the contact movement speed reaches 10m/s, a sampling interval of 1 μ s is required to avoid data loss.

Solution: Adopting FPGA parallel processing architecture, synchronously collecting 4-channel data with a delay of less than 500ns.

② Multi parameter synchronous triggering

Challenge: Ensure strict alignment of displacement, current, and contact signals.

Solution: Use GPS/Beidou timing module to achieve multi-sensor hard synchronization, or use rubidium atomic clock to provide a 10 ⁻¹¹ time reference.

③ Strong adaptability to electromagnetic environment

Challenge: There is a 500kV high-voltage electric field and switch operation overvoltage at the substation site.

Solution: The sensor adopts a double-layer shielding design, and the tester meets the IEC 61000-4-4 electrical fast transient pulse group immunity level 4 standard.

summarize

The high-voltage switch dynamic characteristic tester achieves millisecond level accurate characterization of switch mechanical characteristics through multi-sensor fusion sensing, high-speed signal processing, and intelligent algorithm analysis. The core of its technology lies in the three-dimensional synchronous measurement of time space electrical signals, which can provide early warning of faults, life prediction, and maintenance decision support for substation operation and maintenance. It is a key equipment to ensure the reliable operation of the power system.

Kvtester Electronics Technology Co.,Ltd. is a high-tech enterprise specializing in power testing, testing, research and development, production, and sales of testing equipment. It has been engaged in the electrical testing industry for many years, and its products are of high quality. We welcome customers to come and purchase. Service hotline: 0086-27-81778799, to learn more, visit the official website: www.kvtester.com