In the handover test and preventive test of high-voltage power cables, the AC resonance test system has become an indispensable testing equipment. Faced with the dazzling array of product models and parameter configurations in the market, how to scientifically and efficiently choose a series resonance test device that is suitable for their own cable conditions is a practical problem faced by many power engineering units. As a professional enterprise that has been deeply involved in the high-voltage electrical measurement industry for nearly 22 years, Wuhan UHV Power Technology Co., Ltd., based on its rich industry experience, has sorted out the selection points of cable AC resonance testing systems for its customers.
1、 Clarify experimental requirements and determine core parameters
To select a cable AC resonance test system, it is necessary to first clarify the basic parameters of the tested cable. According to the technical data provided by Wuhan UHV, the core criteria for selection include the voltage level of the cable, the cross-sectional area of the single core, and the length of the cable. These three elements directly determine the required output voltage, resonant frequency range, and system capacity of the experimental system.
Generally speaking, cables with voltage levels of 35kV and below are widely used and require a large amount of testing work, thus placing higher demands on the portability of testing equipment. The design of the AC withstand voltage series resonant device for Wuhan UHV cables fully considers the actual situation of on-site operations, requiring that the weight of components that can be moved by a single person should not exceed 30kg, and the weight of components that can be moved by two people should not exceed 60kg, greatly facilitating on-site handling and layout.
2、 Calculate cable capacitance and match resonant frequency
The capacitance of the cable is a key intermediate parameter in the selection calculation. In the series resonance state, the test frequency is determined by the inductance (L) and capacitance (C) together, with the formula F=1/(2 π√ (LC)). Users can use the "Resonance Calculator" online tool provided on the Wuhan UHV official website to input cable voltage level, single core cross-section, and length, and quickly obtain calculation results such as cable capacitance and corresponding resonance frequency. This tool also supports scanning codes on mobile apps, making it convenient for on-site engineers to access calculations at any time.
3、 Quickly lock the device model by comparing it with a typical configuration plan
After completing preliminary calculations, users can refer to the series resonance scheme provided by Wuhan UHV for equipment selection. The "Resonance Scheme" section on the Wuhan UHV official website lists various typical configuration schemes ranging from 22kVA/22kV to 270kVA/270kV, covering cable withstand voltage test scenarios with different voltage levels and capacity requirements. These solutions are presented in a combination of "capacity voltage", allowing users to quickly match the corresponding model based on their own cable's test voltage and required capacity.
4、 Pay attention to system composition and core technical indicators
A complete cable AC withstand voltage series resonant device mainly consists of a variable frequency control power supply, an excitation transformer, a reactor, a capacitive voltage divider, and an optional compensation capacitor. When selecting, it is also important to focus on the following core technical indicators:
Rated output voltage: The output voltage range of UHV series cable AC withstand voltage series resonant device can reach 0-220kV (AC effective value) and below.
Output frequency: covering 30-300Hz, meeting the resonance frequency requirements of different cables.
System quality factor: The quality factor is not less than 20 under maximum load, reflecting the efficiency and energy-saving advantages of the system.
Waveform distortion rate: Pure sine wave output, waveform distortion rate ≤ 1.0%, effectively preventing harmonic peaks from causing false breakdown of the test sample.
5、 Pay attention to on-site applicability and protective functions
The complexity of the on-site testing environment requires the testing system to have good adaptability and a comprehensive safety protection mechanism. The AC voltage withstand series resonant device for Wuhan UHV cables is powered by a 220V single-phase or 380V three-phase power supply, which is convenient for on-site power supply; The reactor part adopts dry-type epoxy casting, which is beautiful and reliable, suitable for the testing requirements of various cables. In terms of protection functions, the device has multiple safety mechanisms such as overvoltage protection, overcurrent protection, zero start, and system detuning (flashover) protection, effectively ensuring the safety of the test equipment and the test sample.
Wuhan UHV Power Technology Co., Ltd. stated that in addition to standardized series products, the company can also provide customized solutions for customers based on the actual parameters of the test objects. Welcome to come and purchase.
