What is a cable localized discharge and location monitoring device?

What is a cable localized discharge and location monitoring device?

Cable localization and positioning monitoring deviceIt is a professional on-line monitoring system for the assessment of the insulation status of high-voltage power cables. Its core function is to continuously and real-time detect the cable body and its accessories (such as intermediate joints, cable terminals) internal occurrence of thePartial Discharge (PD) signals and spatially localize the discharge source by means of specific algorithms. The system is designed to provide quantitative data for cable insulation defects in theearly warningrespond in singingfault localizationThe

Unlike offline diagnostic tests that require interruption of line operation, theOnline monitoring devicesIt operates at the normal operating voltage and load of the cable and is capable of capturing the characteristics of insulation degradation under actual operating conditions. It outputs data that is implementedCondition-Based Maintenance (CBM) strategy, improve the operational reliability of cable lines, and provide a key basis for full life-cycle asset management.

Table of Contents for this article

• Principle of operation and localization algorithms
• Core monitoring technology and sensor configuration
• Main functions and application areas
• Technical Advantages and Value
• Vendor and system selection criteria

Principle of operation and localization algorithms

Physical signals of localized discharges

Partial discharges (PDs) are bound discharges that do not form penetrating channels in the insulating structure. Each PD event is physically accompanied by the following detectable signals:

• High frequency current pulse: Generates a fast current pulse with a nanosecond rising edge on the metal shield or ground wire of a cable.
• electromagnetic radiation: Electromagnetic waves, mainly in the ultra-high frequency (UHF) band, are radiated from the amplifier source.
• Acoustic Emission (AE): The energy release during the discharge process generates mechanical stress waves in the ultrasonic frequency band.

Detection and localization principles

Cable localized emission monitoringThe workflow of the system consists of two phases: signal detection and signal processing.

1. Detection: Install a set of high sensitivity sensors at key nodes of the cable line, such as on both sides of the cable attachment or on the grounding wire of the cable terminal.transducers, for capturing one or more of the physical signals described above.
2. Localization: localizationmainly based onTime Difference of Arrival (TDOA). When a PD source generates a signal, the signal propagates along the cable line at a specific speed (v) to both sides. By installing synchronized acquisition sensors at points A and B and accurately measuring the time difference (Δt) between the arrival of the signal at these two sensors, the position of the put source (P) can be calculated according to the following equation:
   Distance(AP) - Distance(BP) = v × Δt
   Combined with the known spacing of points A and B, the exact coordinates of the discharge source can be uniquely determined.

Core monitoring technology and sensor configuration

1. High-frequency current transformer method (HFCT)

This technique is accomplished by installing an open-ended cable grounding wire with aHigh Frequency Current Transformers (HFCT) to couple the high-frequency pulsed currents generated by the PD.The HFCT is a non-intrusive sensor that is easy to install and requires no interruption of cable runs, and is currently the most widely usedCable localized emission monitoringTechnology.

2. Ultra-high frequency (UHF) methods

The method focuses onCable accessoriesof internal insulation defect monitoring. By installing near intermediate joints or cable terminationsUHF Antenna SensorThe UHF method has a very high signal-to-noise ratio and resistance to external corona interference, and is highly sensitive to identifying discharge defects within the accessory.

3. Acoustic emission method (AE)

By attaching the surface of the cable accessory housingAcoustic Sensor (AE Sensor)The main advantage of the AE method is its localization capability, which can be achieved by an array of multiple AE sensors for three-dimensional localization of the internal discharge source of an accessory, providing more accurate spatial information for defect diagnosis.

Data analysis and diagnostic techniques

The raw signals collected must be processed by the backend diagnostic software. The core analysis tools arePRPD mapping (phase-resolved partial discharge mapping). The map correlates the amplitude and number of discharge pulses with the phase of the industrial frequency voltage. Different types of insulation defects (e.g., internal air gaps, discharges along the surface, suspended potentials, etc.) produce PRPD maps with completely different characteristics, and by means of a pattern recognition algorithm, theType of insulation defectMake an accurate categorization.

Main functions and application areas

1. Early warning of insulation defects: The system is capable of detecting a weak insulation degradation before it occurs significantly.partial dischargesignals to provide a decision basis for preventive maintenance.
2. Fast and accurate fault localization:: In the event of a cable failure, the system can quickly provide accurate meter-level measurements.fault localizationreports, significantly shortening repair time and reducing outage losses.
3. Quantitative condition assessment of cable lines:: The analysis of long-term trends in PD activities allows for a quantitative assessment of the entire cable route and its accessories.insulation condition, providing data support for asset management and replacement strategies.
4. Construction and installation quality verification:: On-line monitoring of newly constructed or newly rehabilitated cable routes, which can be effectively verifiedintermediate jointrespond in singingcable terminationThe quality of the construction process.
5. Reliability of power supply for critical loads: In critical scenarios such as data centers, rail transportation, airports, hospitals, etc., where unplanned power outages are not permitted, the system is an important technical means of guaranteeing power supply continuity.

Technical Advantages and Value

• Enhance the efficiency of asset management:: Achieve a shift from planned to risk- and condition-based predictive maintenance and optimize resource allocation.
• Reducing the risk of unplanned outages: Significantly reduce the probability of sudden power outages due to cable insulation breakdowns through effective early warning.
• Optimize maintenance strategy and costs:: Precisionfault localizationBlind testing and excavation is avoided, directly reducing maintenance costs and time.
• Enhanced system operational security:: Timely detection and treatment of serious insulation defects to prevent secondary disasters such as electrical fires caused by cable faults.

Vendor and system selection criteria

1. Applicability and comprehensiveness of sensing technologies:: Vendors should be able to provide a package that includesHFCT,UHFrespond in singingAEA wide range of sensor solutions are available to cope with different cable types and field conditions.
2. Accuracy and Robustness of Localization Algorithms:: The core of the system islocalizationAlgorithm. Its localization accuracy and stability need to be evaluated under different signal-to-noise ratios and complex line topologies.
3. Analytical capabilities of diagnostic software: The software platform should have automatedPRPD mappingidentification and classification, noise suppression, and long-term data trend analysis functions.
4. Electromagnetic compatibility (EMC) and environmental compatibility of the system: The product must pass rigorous EMC testing and have an industrial design capable of long-term reliable operation in cable trenches or tunnels with high humidity and wide temperature differences.

Why choose Inotera's cable localized discharge monitoring solution?

INNOTD (Fuzhou) Sales Limited (INNOTD) Specializing in world-class online monitoring technology for critical power assets.

• Multi-technology convergence program: We offer a wide range of technologies based on HFCT, UHF and AE.Integrated Monitoring ProgramIt can be optimized according to the characteristics of your line, and can achieve a dead-end coverage of the cable body and accessories.
• Advanced positioning and diagnostic engine: Our system is equipped with self-developed and extensively field-provenHighly accurate fault localization algorithmsrespond in singingIntelligent PRPD Diagnostic Expert System, capable of extracting clear and accurate fault information from complex signals.
• Integrated Intelligent Platform: Our local discharge monitoring system can be seamlessly integrated into Inotera's comprehensive online monitoring platform, realizing the integration with theDistributed fiber optic temperature measurement (DTS) The multi-information fusion analysis of such data provides the most comprehensive health assessment of cable lines.
• Professional full-process services: From preliminary site survey and program design, to mid-term installation and commissioning, technical training, and later continuous data analysis and diagnostic support, our team of experts provides you with end-to-end professional services.

Choosing Inotera is choosing a 24/7 intelligent guardian for your underground power arteries.

The content of this article is only a general technical science and does not represent the performance and specifications of any specific product of our company. For detailed product information, solutions and quotations, please be sure to contact us for...].

Contact us today for a customized local discharge and location monitoring solution for your cable lines.