Iso Phase Bus Duct Monitoring | Generation Monitoring Solutions

Why Should I Monitor Iso Phase Bus Ducts?

The availability of a power plant depends crucially on the reliability of major high voltage components such as the generator, isolated phase bus (IPB) and the generator step-up transformer (GSU). It is important for power plants to have reliable isolated phase bus ducts. The key benefits to implementing online monitoring are

  • Increasing safety for workers
  • Reducing unexpected failures to increase plant reliability
  • Reducing unplanned outages which saves time and money

Online condition-based monitoring collects data generated during the assets normal operating conditions to get real-time awareness of problems.

Isolated Phase Bus Duct Monitoring

What causes failure in an iso phase bus duct?

Generation Site

Isolated phase bus, also known as the isophase bus, failure can occur for several different reasons. Poor insulation, dirt, condensation and water intrusion can all be contributing factors as to why the isophase experiences complications.

High voltage assets in power plants are interconnected and if they are monitored in isolation, it could result in false conclusions of the origin of the fault sources and false alarms. This is often an overlooked issue and was addressed using a choice and combination of conventional and unconventional sensors.

Manual Inspection vs Online Monitoring

The condition of generation assets are usually determined through periodic manual inspections during an outage. The disadvantage of periodic inspections is that the time interval between two maintenance activities is not always sufficient to identify developing issues prior to failure. Periodic maintenance is often performed when the asset is not in service or the plant is in outage and the actual state of the asset with respect to time and plant operation condition is often not available for diagnosis. Periodic maintenance frequently results in the maintenance of healthy assets, increasing maintenance costs, and the possibility of human error.

Online Monitoring for Isolated Phase Bus Ducts

The isolated phase bus (IPB) interconnects the electric generator and the generator-step-up (GSU) transformer.

Because partial discharge (PD) activity is often present well in advance of insulation failure, it provides the most evident indication of defects and deterioration in an IPB.

Asset managers can evaluate partial discharge activity over time and make informed strategic decisions regarding the timely repair or replacement of the equipment before an unexpected outage occurs.

Use Realtime Data with Isolated Phase Bus Duct Monitoring


GPCS Sensor

Typically, there is an isolating joint between the generator’s main terminal box and the IPB enclosure. This isolating joint exists to prevent circulating currents in the IPB. The GPCS sensor is installed across this isolation joint and is designed to transmit only high frequency pulses caused by partial discharges.


Coupling Capacitor

Coupling Capacitor Sensors

The sensor has been designed to be used like the bus support insulator of the Isolated Phase Bus (IPB) or as coupling capacitor. It consists of a “stacked-mica” capacitor sealed with a special epoxy resin suitable for operation in extreme industrial environments.


Rotating Machine Monitor

Partial Discharge Monitor

The partial discharge monitor continually monitors partial discharge (PD), and stores and correlates operating dynamics. The SCM provides information on the health of the medium voltage insulation systems of switchgear, cables, bus duct and unit substations.


DRPD-15 Portable PD Analyzer

DRPD-15 Portable PD Analyzer

Designed with a rugged enclosure, the analyzer is lightweight and is able to be used with a connected computer or independently.


Comprehensive Partial Discharge Monitoring Approach

It is important to consider a comprehensive partial discharge monitoring approach. PD can occur in generators, isolated bus ducts, step up transformers, and switchgear. Comprehensive monitoring of the entire power train can greatly increase the ability to pinpoint problem locations. To learn more about comprehensive PD Monitoring, visit our overview page.


Additional Resources


Measuring methods for maximizing the reliability of iso phase bus ducts.


Continuous PD Monitoring for Iso Phase Bus Ducts


Success Story of PD Monitoring at a Generation Power Plant.