Electric Motor Life Expectancy

Electric Motor Life Expectancy

The lifespan of an electric motor can last anywhere between 15 to 20 years, provided it is used within specified values and normal operating conditions. Well under test conditions the lifespan of an electric motor can last anywhere between 15 to 20 years, provided it is used within specified values and normal operating conditions. In terms of miles tests have concluded that they can go upto a 400000+ mile range in their lifetime. Claims have been made that the PMSRM Unit drive in Tesla have passed the 1million mile test.

The factors that govern the life expectancy of EV motors include:

• Unexpected load changes
• Fluctuations in input power
• Improper installation of the machine
• Different environmental factors like humidity, temperature, etc

Effect of various factors on the electric motors in an EV.

THE IMPACT OF TORQUE

Torque is the amount of rotational force generated by a motor characterizes instant mechanical output. Efficient torque monitoring can predict the condition of the motor including the load. When running under specified torque limits, the motor offers smooth, reliable, and cost-efficient performance.

POWER QUALITY MATTERS A LOT

Irregularities can cause critical damage to the motor of an electric vehicle. These include unbalance, harmonics, transients, etc. Unbalance is subject to both current and voltage, often leading to burnt windings and higher motor temperature. Harmonics can create a distortion of both current and voltage causing motors to overheat or even motor failure. Transients lead to damaging of motor insulation and tripping of overvoltage circuits.
Mechanical overload stresses motor components like insulation, couplings, bearings, etc, resulting in a dip in the efficiency as well as premature failure. Thus efficiency and energy consumption can be regulated by identifying and repairing faulty or poorly performing motors.

KEY CAUSES OF MOTOR FAILURE

Motor failure can be delayed to a great extent if properly maintained. If not properly maintained, motors are prone to breaking down more frequently than expected. Proper understanding of motor behavior and maintaining it enables the motor to attain its maximum possible lifespan. Let’s have a look at such key causes.

CONTAMINATION

Chemicals, dirt, and dust act as contaminants that are the major causes of motor failure. Foreign particles inside a motor deteriorate bearing balls and raceways, causing more wear and vibrations to an extent that it blocks the cooling fan limiting its ability to regulate temperatures causing overheating issues.

OVERHEATING

Overheating in electric motors leads to insulation failures. Probable causes are high temperature operating environment or poor power quality resulting in frequent breakdowns.

VIBRATION

Premature failures are a very probable result of unwanted vibrations in a motor. Often caused by the faulty placement of motor on unstable or uneven surface or due to corrosion, misalignment, etc, these vibrations significantly lower the lifespan of the motor.

LOW RESISTANCE

Degradation of the windings’ insulation due to physical damage, corrosion, and overheating, etc are the causes of low resistance in motors, resulting in improper isolation between motor windings or conductors making way for short circuits and leakages, hence motor failures.

ELECTRICAL OVERLOAD

Excessive current flow through the motor windings exceeding the safety/efficiency ratings results in electrical overload. Lower supply of voltage results in excess current to be drawn in motor, in an attempt to maintain its torque. Excessive voltage supply and conductor short-circuit add to the factors that cause electrical overload.

There are many factors that affect the life expectancy of an AC induction motor (or any electric motor). These factors can include input power problems, improper mechanical installations, malfunctions in the load, environmental factors, among others. Assuming that the motor is being operated under normal conditions, sized correctly for the application and within the manufacturer’s design requirements, it can last 15 years or more. 1 However, rewinding a motor usually is the result of a catastrophic failure in the motor’s insulation and windings and is usually due to a thermal breakdown. Hence, generally speaking, a motor that requires rewinding may not have been operated under normal conditions. Motors are frequently replaced rather than rewound due to costs, convenience and the claim that rewinding may reduce the motor’s efficiency. 2 Early failure of motor bearings is usually the result of improper mechanical installation causing undesirable forces acting on the bearings, or simply poor maintenance. Bearings should be inspected regularly for lubrication and uncharacteristic noises. Their life expectancy depends on factors previously cited. 3