Motor and Generator High Voltage Testing
Your high voltage rotating plant is a valuable asset which needs to operate safely, reliably and efficiently for many years, in order to achieve financial payback and profitability for your operation. It is imperative that your engineers understand the ongoing condition of the plants HV motors and generators to enable predictive maintenance rather than costly reactive maintenance.
Megavar specialises in testing and condition monitoring of HV motors and generators, to identify factors that may lead to shortened machine life or catastrophic failure. Megavar utilises state of the art test apparatus to give the most accurate picture of the condition of the plant under test. Ensuring that your maintenance engineers have the best data available on the condition of vital rotating plant.
EL CID (Electromagnetic Core Imperfection Detector)
Megavar owns and operates the latest EL CID Evolution from IRIS Power. This unit can be used to test hydro generators, turbo generators and large motors for stator core inter-lamination imperfections that cause heating and damage during machine operation. “Electomagnetic core imperfection detection (EL CID) testing is accepted world-wide for reliable and safe detection of stator core inter-laminar faults (CIGRE, 2004)”
RSO (Recurrent Surge Oscillograph)
The RSO is used to identify the presence of generator rotor shorted turns. Shorted turns in generator cylindrical rotor field windings can contribute to machine vibration problems due to uneven heating and watt losses in shorted windings as well as unbalanced magnetic flux in the air gap. Megavar utilises the RTS 02 rotor test set and an oscilloscope to enable testing according to the AEEGE and AEE 100 test methods.
Dielectric loss angle measurements (DLA, power factor, dissipation factor, DDF)
The measurement and trending of the dielectric loss angle of stator winding insulation is an important tool in the condition monitoring of the machine stator. The values and the trend will show degradation of the insulation and can be used in predictive assessment to determine the best time for costly maintenance. Megavar utilises the Omicron CPC+TD1 test system along with the omicron reactor to perform measurements to the highest accuracy.
PD Measurement (Partial Discharge)
The Partial Discharge phenomena is a sign of degrading insulation capacity. Partial Discharge detection and monitoring is vitally important, as it often precedes an electrical insulation breakdown in high voltage equipment. Our engineers use the Omicron MPD600 test system and a high voltage source to detect and measure PD in stator windings.
IR and PI (insulation resistance and polarisation index)
One of the cornerstone tests for motors and generators is the insulation resistance and polarisation index. These tests indicate the quality insulating quality of a dielectric by applying a DC voltage and measuring the current flow to present the insulation value in ohms and trend this value over a time interval of 10 minutes. Megavar uses high quality Megger units and is able to test to 10kV in accordance with IEEE43-2000 recommendations for motors windings rated above 12kV.
