The typical epoxy-mica insulation system of rotating machines is a 'forgiving', i. e. a comparably stable insulation system. Due to this electrical stability, partial discharge activity acts as an indicator for a variety of defect mechanisms. Besides the mere electrical aging, further problems, such as contamination, vibration, or mechanical aging find their expression in the phase-resolved partial discharge pattern.
Power Diagnostix offers various instruments for continuous monitoring, schedule-based routine testing and in-depth analysis of rotating machines. The instruments and their control software were continuously improved, based on more than twenty years of testing numerous generators and motors.
Permanently installed partial discharge couplers greatly simplify on-line testing using the ICMsystem without any interruption or downtime. Continuous on-line monitoring of the discharge activity with a permanently installed ICMmonitor helps optimizing maintenance intervals and reducing costs, while improving the level of equipment dependability.
Tan Delta Measurements
The loss factor or tan delta measurement allows an evaluation of the condition of the complete insulation of a stator winding. All resistive losses between HV potential and ground are measured. Typical values are in a range of 10-3 to 10-2.
The TDAcompact is a digital tanδ and power factor analyzer for off-line dielectric testing to assess the overall healthof the insulation system. Its fiber optic signal transmission simplifies connection even on grounded equipment. The unit comes with reference capacitor and can be combined with any external high voltage source.
Partial Discharge Monitoring
Based on the stand-alone ICMmonitor unit connected to an individual machine, larger networks supervising amultitude of generators in combined cycle thermal power plants or pump storage hydro power plants have been realized. Such networks include full control of the local instrument via global Intranet access as well as visualization of the monitoring data in monitoring centers. The ICMmonitor software offers automated scanning, pattern acquisition, and analysis of the trending data.
High voltage motors are key-components in refineries and the production of technical gasses according to the Linde process. Here, unplanned outages can cause immense losses. Further, such motors serve in thermal and nuclear power plants to run the (emergency) cooling system, for example. Here, failure of a motor stator winding can cause critical subsequent damage. Installing specially suited coupling capacitors offers schedule based measurements as well as continuous monitoring for the assessment of the insulation condition.