Permanent Multi-Channel Partial Discharge Monitoring Equipment: Functions, Applications, and Selection Guide

Permanent Multi-Channel Partial Discharge Monitoring Equipment: Functions, Applications, and Selection Guide

Permanent multi-channel partial discharge (PD) monitoring equipment is designed to monitor partial discharge activity in high-voltage electrical assets over extended periods. Sensors installed on or near the monitored equipment collect PD-related signals, while a monitoring unit processes, records, and analyzes the data.

Unlike a portable PD tester used for scheduled diagnostic tests, a permanent monitoring system is installed for recurring or continuous observation during equipment operation, subject to its design and configured acquisition cycle.

A typical system may include:

Permanently installed PD sensors

A multi-channel data acquisition unit

Signal conditioning and noise-rejection functions

Monitoring and diagnostic software

Long-term data storage and trend analysis

Configurable alarms and communication interfaces

Multi-channel systems can monitor several sensors or locations in parallel. This helps engineers compare activity across channels and investigate potential discharge sources, provided the channels, sensors, and acquisition timing are suitable for that analysis. Commercial monitoring systems demonstrate configurations with multiple sensor types, historical data, and substation communication interfaces.

A permanent PD monitoring system generally follows this process:

PD Sensors

Detect signals associated with partial discharge activity

Multi-Channel Data Acquisition

Collects and processes signals from configured channels

Analysis and Historical Data

Displays signal patterns, trends, and configured diagnostic indicators

Alarm and Monitoring Interface

Notifies operators when configured thresholds or rules are met

The system can collect data at configured intervals or continuously, depending on its architecture. Software may display signal magnitude, pulse activity, phase-resolved patterns, and historical trends. Alarm logic and diagnostic functions vary by model and application.

3.1 Multi-Channel Signal Acquisition

Multiple acquisition channels allow one monitoring unit to collect data from several installed sensors or monitoring points. Depending on the system, channels may monitor different phases, cable terminations, transformer locations, or sections of switchgear.

When selecting a multi-channel system, verify:

Number of channels that can measure simultaneously

Supported sensor types for each channel

Whether channel timing is synchronized

Whether channels can be expanded later

Maximum cable or communication distances for the proposed installation

The number of physical inputs does not automatically establish that all channels support the same measurement method or performance. Check the proposed channel configuration carefully.

3.2 Continuous Monitoring and Trend Analysis

Permanent monitoring can reveal changes in PD-related activity over time. Trend data may help maintenance teams identify assets that require further inspection or diagnostic testing.

Depending on the system, historical records may include signal magnitude, pulse count, PRPD patterns, alarms, and operating conditions.

Trend interpretation should account for changes in sensor performance, noise, load, temperature, operating voltage, and acquisition settings. An increase in measured activity is a reason for investigation, not by itself proof of imminent failure.

3.3 Noise Rejection and Signal Classification

Electrical substations and industrial facilities may contain switching noise, radio-frequency interference, and other signals that complicate PD monitoring.

A monitoring system may use filtering, phase analysis, signal comparison, gating, or pattern-recognition algorithms to help distinguish relevant PD activity from interference. The effectiveness depends on the sensor technology, installation, signal environment, and algorithm design.

3.4 Alarm Management and Remote Access

Depending on the configuration, the system may provide:

Configurable warning and alarm thresholds

Local or remote alarm notifications

Historical data review

Web-based monitoring interfaces

Relay outputs or industrial communication protocols

Integration with SCADA or asset management systems

These functions help operators prioritize investigation and maintenance. Verify the available communication protocols, cybersecurity requirements, alarm logic, and interfaces before integration into an existing control system.

Power Transformers

Permanent monitoring can help detect changes in PD-related signals around instrumented transformers. Depending on the design, systems may use UHF sensors, bushing test-tap connections, or acoustic sensors to support insulation condition assessment.

Gas-Insulated Switchgear (GIS)

UHF-based monitoring is commonly used to detect electromagnetic signals associated with PD activity in GIS. Multiple sensors can support monitoring at different locations, subject to the installation and system design.

Power Cables and Terminations

Installed HFCT, UHF, or other compatible sensors can monitor PD-related signals at selected cable terminations or joints. Sensor selection depends on the cable design and monitoring objective.

Generators and High-Voltage Motors

Suitable PD monitoring systems can track discharge-related signals from instrumented rotating machines. Sensor design, operating conditions, and interpretation methods must match the machine type.

These applications require different sensor technologies and installation methods. A system designed for GIS UHF monitoring should not automatically be assumed suitable for charge-based transformer measurements or rotating-machine monitoring.

Both systems support insulation assessment, but they serve different maintenance needs.

For critical assets, a permanent monitoring system can be complemented by portable diagnostic testing when a trend or alarm requires further investigation.

The appropriate standard depends on the measurement method and the asset being monitored.

IEC 60270:2025 addresses charge-based partial discharge measurement, including measuring circuits, calibration, test procedures, and related instrumentation requirements. It should not be treated as a universal specification for every online sensor technology.

ng a supplier's compliance statement, ask which measurement method, sensor configuration, calibration or sensitivity-check procedure, and performance criteria are covered. A general reference to an IEC standard does not establish that every function of a monitoring system has been independently verified.

Before purchasing, define the monitored assets, required sensor technology, communication architecture, and long-term monitoring objectives.

Selection tip: Start with the assets and monitoring objectives, then determine the sensor type and channel count. More channels do not necessarily mean better diagnosis if the sensors, signal quality, and analysis method are not suitable for the application.

Step 1 - Define the monitoring plan

Identify the assets, potential PD measurement points, sensor technology, required channel count, and alarm objectives.

Step 2 - Install the sensors

Install sensors and interfaces according to the approved design, equipment requirements, and electrical safety procedures.

Step 3 - Configure acquisition and communications

Configure channel assignments, acquisition parameters, time synchronization where required, data storage, and remote access.

Step 4 - Establish baseline data

Verify sensor signals, background noise, data quality, and alarm settings. Record baseline operating conditions for future comparison.

Step 5 - Monitor trends and investigate alarms

Review changes in the recorded signals and use appropriate follow-up diagnostic tests before making maintenance decisions.

Installation on energized high-voltage equipment must be performed only where the sensor design, installation method, and approved work procedure permit it. Follow site safety rules and the equipment manufacturer's instructions.

Permanent multi-channel partial discharge monitoring equipment supports long-term observation of insulation-related activity in critical high-voltage assets. By combining installed sensors, multi-channel data acquisition, trend analysis, and configurable alarms, it can help maintenance teams identify changes that require further investigation.

The right configuration depends on the asset type, sensor technology, channel count, communication requirements, and diagnostic objectives. A well-designed monitoring system should be specified around the intended application rather than channel count alone.

Goldhome provides high-voltage electrical testing equipment solutions for power utilities, substations, manufacturers, and electrical service contractors.

Website: www.goldhomehipot.com

Contact: +86 18971538425