18-12-2009, 01:52 AM
Abstract
Induction motors can be protected using some components, such as timers, contactors, voltage, and current relays. This is the classical method and involves mechanical dynamic parts.Protection of an induction motor (IM) against problems,like overvoltage, overcurrent, overload, overtemperature, and undervoltage, is very important, because it is used widely in industry as an actuator.Computer based and PIC(programmable integrated circuit ) based techniques are available. The computer-based protection method requires an analog-to-digital conversion card, and the PIC-based protection method does not visualize the electrical parameters measured.
New method using PLC
In this method, all contactors, timers, relays, and the conversion card are eliminated. And the voltages, the currents, the speed, and the temperature values of the motor, and the problems occurred in the system, are monitored and warning messages are shown on the computer screen.
The stator current monitoring method for incipient fault detection in induction
machines is widely used for some time.It has advantages such as:
-No additional, potentially unreliable, sensors are necessary, above those
current sensors already used for motor protection;
-Electrical faults, such as broken rotor bars, rotor unbalances, bearing faults and
stator winding faults can be observed; and driven load conditions can be
determined.
A fault detection algorithm is available to be used in the condition monitoring of the squirrel-cage induction motors, very widely used in industry all around the world.
THE MOTOR CURRENT SIGNATURE ANALYSIS
This technique depends upon locating by spectrum analysis specific harmonic components in the line current produced of unique rotating flux components caused by faults such as broken rotor bars, air-gap eccentricity and shorted turns in stator windings, etc.
The assumptions taken here are:
-The speed of the machine is constant and known.
- The stator fundamental frequency is constant.
-The load is constant.
-The machine is sufficiently loaded in order to separate the sidebands from the
fundamental.
[attachment=633]
The exact IEEE paper on the subject can be referred at this link:
http://ieeexplore.ieeexpl/freeabs_all.js...er=4603060
You have to have an IEEE membership or your institution must have a subscription to the IEEE Xplore digital library. Or try getting from friends.
Induction motors can be protected using some components, such as timers, contactors, voltage, and current relays. This is the classical method and involves mechanical dynamic parts.Protection of an induction motor (IM) against problems,like overvoltage, overcurrent, overload, overtemperature, and undervoltage, is very important, because it is used widely in industry as an actuator.Computer based and PIC(programmable integrated circuit ) based techniques are available. The computer-based protection method requires an analog-to-digital conversion card, and the PIC-based protection method does not visualize the electrical parameters measured.
New method using PLC
In this method, all contactors, timers, relays, and the conversion card are eliminated. And the voltages, the currents, the speed, and the temperature values of the motor, and the problems occurred in the system, are monitored and warning messages are shown on the computer screen.
The stator current monitoring method for incipient fault detection in induction
machines is widely used for some time.It has advantages such as:
-No additional, potentially unreliable, sensors are necessary, above those
current sensors already used for motor protection;
-Electrical faults, such as broken rotor bars, rotor unbalances, bearing faults and
stator winding faults can be observed; and driven load conditions can be
determined.
A fault detection algorithm is available to be used in the condition monitoring of the squirrel-cage induction motors, very widely used in industry all around the world.
THE MOTOR CURRENT SIGNATURE ANALYSIS
This technique depends upon locating by spectrum analysis specific harmonic components in the line current produced of unique rotating flux components caused by faults such as broken rotor bars, air-gap eccentricity and shorted turns in stator windings, etc.
The assumptions taken here are:
-The speed of the machine is constant and known.
- The stator fundamental frequency is constant.
-The load is constant.
-The machine is sufficiently loaded in order to separate the sidebands from the
fundamental.
[attachment=633]
The exact IEEE paper on the subject can be referred at this link:
http://ieeexplore.ieeexpl/freeabs_all.js...er=4603060
You have to have an IEEE membership or your institution must have a subscription to the IEEE Xplore digital library. Or try getting from friends.
