Electrical Condition Monitoring Techniques

What it is ... 

There are a range of condition monitoring techniques that can be used on electrical equipment and the list below indicates some of the commonly used techniques and related applications.

Note that some of these electrical measuring techniques are appropriate for monitoring the condition of mechanical equipment that is connected to the electrical equipment. For example, using a model-based voltage and current system can be a very effective way of monitoring the condition of the bearings in a submerged pump and so may be a particularly appropriate technique for this type of equipment that is hard to monitor by other, more conventional techniques.

Electrical condition monitoring techniques include:
  • Conventional test meters: used to check out overall circuitry to an electric motor, covering the resistance of the windings and the integrity of the insulation.
  • Specialised motor test meters: used in either a static mode to check such parameters as resistance, inductance, impedance, capacitance and phase angle / dissipation factor, or in a dynamic mode to check current and voltage unbalance, distortion, rotor conditions, power levels and power factor.
  • Motor current signature analysis (MCSA): used for identifying developing problems inside motors, particularly the development of defects in the rotor cage structure, such as rotor bar cracking.
  • Model-based voltage and current (MBVI) systems: these identify the distortions to the motor current that have not been caused by distortions of the voltage supply and therefore must have come from phenomena within the motor and driven equipment system, including a wide range of mechanical, electrical and operational problems.
  • Partial discharge testing: used to detect small electrical discharges that take place within insulation; these small discharges can be an early indication of insulation deterioration. Each discharge (think of it like a small internal spark) carries a small but measurable unit of electrical charge that can be detected using the right sort of equipment.

Applications for electrical condition monitoring techniques include motors and their driven equipment, generators and their prime movers, transformers, switchgear, inverters, supply sources, etc.