In this residual life assessment package we will assess the life and condition

In this residual life assessment package we will

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In this residual life assessment package, we will assess the life and condition of total insulation system of electrical rotating machine consisting of high voltage generators and motors. Normal deterioration with age 18% Poor Ventilation/ Cooling 8% Aggressive chemicals 7% Poor Lubrication 5% High Vibration 9% Abnormal Frequency 1% Abnormal Voltage 5% Abnormal Moisture 18% High Ambient Temperature 8% Persistent Overloading 7% Other 14%
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ROTARY ELECTRICAL SERVICES LTD RESIDUAL LIFE ASSESSMENT (RLA) SERVICES Rotary, with over five decades of experience in the field of servicing of electrical rotating machines, have found out several innovative tests and technologies for assessing the current physical condition of the machine. With a backup of large database, build after performing the Root Cause Failure Analysis on several hundred machines, Rotary now offers Residual Life Assessment (RLA) Services , as per the following flowchart: Analyzing Operational Data Present state evaluation by diagnostic tests Stress evaluation by finite element methods Identification of weak link in the form of defect (Crack or tree initiation) Determining the residual life The machine insulation is subjected to constant thermal stress that causes aging as given by the Arrhenius chemical degradation rate equation and charts for different insulation class. Besides this, there are cyclic thermal stresses caused by frequent starts/stop of the machine. This causes reduction in tensile strength of the insulation, which can be expressed in terms of residual breakdown voltage (RBDV). The basic Arrhenius curves are modified to account for the operational hours and starts/stops as shown. It is assumed that the BDV for new machines is 100%. There is initial reduction in BDV (shown by BDV1) due to stresses caused by heating of windings and insulation, corresponding to the operating hours. The stresses are high during starting and stopping conditions, which further reduce the BDV (shown by BDV2). The value of 60% for BDV is taken as the critical value, below which the machine is at high risk of insulation failure. Y = m 1 *Op hrs + 100 Y = m 2 *Starts-stops + 100 Y = m 2 *Starts-stops + BDV1 BDV % Operating hours No. of starts/stops 100 % BDV2 % BDV1 % 60 %
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ROTARY ELECTRICAL SERVICES LTD RESIDUAL LIFE ASSESSMENT (RLA) SERVICES The above analysis based on operational data can offer life estimation at 65% confidence level. The next step in RLA is to evaluate the present machine condition by diagnostic test. Rotary presents you a special bouquet of tests that doesn’t just tell you the machine is good or bad, but goes far ahead in understanding the physics involved and answers your query lucidly informing which component needs attention and why. C A P A C I T A N & C E T A N DE L T A N O N L I N E A R A N A L Y S I S P A R T I A L D I S C H A R G E D C H I P O T T E S T W E D G E M A P G P I N C O U P L I N G R E S I S T A N C E R E C U R R E N T S U R G E O S C I L L O S C O P E This bouquet of tests gives in depth information regarding machine abnormalities like
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  • Spring '18
  • Strength of materials, Tensile strength, Stator, RLA

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