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#Motor winding resistance value Offline#

This will make you certain that insulation resistance of a de-energized motor will reduce after commencing the motor.

These damages can have major influence on the complete functioning of the motor and must be provided significant attention when troubleshooting these motors.Įlectric Motor Insulation Resistance TestingĮlectric motor insulation exhibits a negative temperature coefficient, meaning as temperature increases, resistance decreases. Failed components in the resistor bank are common and often overlooked when troubleshooting. Wound rotor motors have a three-phase winding wound on the rotor which is connected to three phases of start-up resistors to provide current and speed control on start-up. This will adversely affect the Standard Test results, possibly creating higher than normal resistive and inductive imbalances. Pumps that are attached to a shared header might remain rotating if other pumps attached to the header are functioning. Fans may continue to slowly rotate due to drafting in the Plenum.

#Motor winding resistance value Offline#

NOTE: This paper was edited from the original version of the IEEE paper published in 2003.Ĭheck for fan or pump motor rotation when testing offline with the MCE.

Following the failure, additional testing investigated the possible deteriorating effects on turn-turn insulation due to impulse testing beyond the motor’s dielectric breakdown. This was accomplished by putting a low voltage motor through extensive testing rigors, until inducing a failure.

Are motors with a turn-turn short able to perform continued function?.

After failing an impulse test, are motor with weak insulation able to operate?.

Can DC Resistance, Inductance, Megger or HiPot tests diagnose weak turn-to-turn insulation?.

Can impulse testing damage healthy or deteriorated insulation?.

Below are few questions that helps in explaining the influence of extensive impulse testing on a motor. They are:Įlectric Motor impulse testing is an integral part of predictive maintenance of electrical motors. What is Done During Electric Motor Testing? There are various kinds of testing done on motor. Some of the winding faults are:įault finding of at least one of the above can save your facility countless hours of shut down and numerous dollars in savings. This creates extra stress and increase in temperature across the fault, which increases until the winding fails. They start as energy crossing an insulation fault like moisture, which sets apart at least one turn. Winding defects occurs due to contamination, ageing of insulation, thermal overload, power surges, damaged wire/materials, and other causes. Many diagnostic tools, such as clamp-on ammeters, temperature sensors, a Megger or oscilloscope, can help illuminate these issues. The other 52% of failures are mechanical faults.

The 48% can be again divided into rotor problems (12%) and winding problems (36%). The Electric Power Research Institute (EPRI) conducted a survey which brought into the light that, 48% of motor failures are because of electrical failures. Why is Electric Motor Testing Done?Īfter bearing failure, electrical faults are the most common mode of motor failure, so in addition, a properly planned electrical testing scheme is important for making sure of the plant reliability. But smart companies, understands that without proper maintenance programs, there is billions of dollars of lost revenue through increased motor repair costs, downtime, and waste in industrial and commercial companies. Electric Motor Testing is usually the first thing to be sacrificed when cutting back on operational expenses. Electrical maintenance programs are designed to increase equipment promptness and uptime while decreasing capital operating cost.