Iso Phase Bus Duct Monitoring | Generation Monitoring Solutions

Why Should I Monitor Iso Phase Bus Ducts?

Power plant availability depends on the reliability of the generator, isolated phase bus and the generation step-up (GSU) transformer. It is important for power plants to have reliable isolated phase bus ducts. Therefore, 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 monitoring collects data generated during the asset’s 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 are all contributing factors as to why the isophase experiences complications.

High voltage assets in power plants are interconnected. Therefore, if they are monitored in isolation, it could result in false conclusions of the fault source origin 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 between two inspections is not always sufficient to identify developing issues. Perform periodic maintenance 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. Consequently, 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. Install the GPCS sensor across this isolation joint and transmit only high frequency pulses caused by partial discharges.


Coupling Capacitor

Coupling Capacitor Sensors

Use the coupling capacitor sensor as the bus support insulator of the Isolated Phase Bus (IPB) or as a 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.


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.