Generator Brush Gear Monitoring System

Diagnostic and monitoring system MOSAD®-IRIS

Long term experience shows that the brush gear is the most vulnerable part of the generator. Continuous montoring of the brush gear enables to prevent uneven brush load (overloaded or poorly conducting brushes) and thus reduce the slip rings wear or in extreme cases prevent the destruction of the brush gear.
Permanent control over the brush gear device provided by remote or local control and the system of alarms enable targeted maintenance interventions and significantly minimizes their frequency.

The device measures the DC current flowing through each carbon brush. The current sensor is based on indirect compensation method and includes Hall effect sensor, compensation winding circuit and related electronics.
The IRIS transducers can be adapted to various types of brush gears according to generator manufacturer´s requirements. Currently two types of transducers exist: IRIS 4.1 ( a compact block of 4 transducers) and IRIS 1.1 (with bracket holding for 1 individual brush).

MOSAD®-IRIS is fully autonomous, yet it is advisable to integrate it in an existing information system.

 

Processing and display unit features

  • Installation near to the generator.
  • Measured values displayed in accordance with the generator brush layout.
  • Displaying of actual current values as well as short-time and long-time averages.
  • Statistical evaluation.
  • Colour distinguishing between current levels of different acceptability.
  • Adjustable parameters of average calculations and acceptability limits.
  • Local and remote alarms upon exceeding acceptability limits.
  • Providing data to a superior system, data archiving.

Advantages and use of the system

  • Prevents brush gear failure due to timely information to operator.
  • Makes brush gear maintenance easier and more effective.
  • High resistance to conductive dust, vibrations and electromagnetic interference.
  • Prevents destruction of the brush gear device.
  • On-line connection to existing information system.
  • Provides high measurement accuracy.
  • Reliable information for strategic decisions of operators, enables evaluation of brush gear performance (air moisturizing, material of brush coating, surface of the slip rings etc.).
  • Unattended operation.
  • Transducers adaptable to any brush gear design. Synchronisation with other systems or components through a common time standard.
To increase operational safety of generators with hydrogen cooling, the transducer power supply automatically switches off, if the generator is disconnected from the grid.