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    Drive FundamentalsDrive/Motor BasicsRevision 1.0Drive and Motor BasicsIntroductionAn adjustable speed drive is a device that controls speed, and direction of an AC or DC motor.Some high performance drives are able to run in torque regulation mode.DC DrivesDC Drive Control SystemA basic DC drive c...

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    DriveMotorBasics01.docPage 2 of 11Series WoundThe series-wound motor has the field connected in series with the armature. Although the series-wound motor offers high starting torque, it has poor speed regulation. Series-wound motors aregenerally used on low speed, very heavy loads.Compound Woun...

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    DriveMotorBasics01.docPage 3 of 11Armature voltage controlled DC drives are capable of providing rated current and torque at anyspeed between zero and the base (rated) speed of the motor. These drives use a fixed fieldsupply and give motor characteristics as seen in Figure 1.2. The motor output ...

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    DriveMotorBasics01.docPage 4 of 11 Figure 1.3Constant Torque and HorsepowerCurvesOperation above Base SpeedOne characteristic of a shunt-wound DC motor is that a reduction in rated field current at a givenarmature voltage will result in an increase in speed and lower torque output per unit of arm...

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    DriveMotorBasics01.docPage 5 of 11pulse width modulated “PWM” technique. With this method, a DC voltage is applied to the motorwindings in time controlled pulses in order to achieve current that approximates a sine wave of thedesired frequency. IGBTs or Isolated Gate Bipolar Transistors are t...

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    DriveMotorBasics01.docPage 6 of 11As the motor begins to accelerate, the torque drops off, reaching a minimum value, called Pull-upTorque, between 25-40% of synchronous speed (Point B). Pull-up Torque is caused by harmonicsthat result from the stator windings being concentrated in slots. If the w...

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    DriveMotorBasics01.docPage 7 of 11account for the largest share of induction motors sold. The slip of a Design B motor isapproximately 3-5% or less. Design B AC Induction MotorDesign C — motors uses a two-cage rotor design, high resistance for starting low resistance forrunning. This creates ...

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    DriveMotorBasics01.docPage 8 of 11 Design D AC Induction Motor

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    DriveMotorBasics01.docPage 9 of 11Synchronous MotorsSynchronous motors operate at synchronism with the line frequency and maintain a constantspeed regardless of load without sophisticated electronic control. The two most common types ofsynchronous motors are reluctance and permanent magnet. The...

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    DriveMotorBasics01.docPage 10 of 11A motor rated for 60hz operation may be run at higher frequencies when powered by RockwellAutomation AC Drive. The top speed depends upon the voltage limits of the motor and it’smechanical balancing. 230V and 460V motors normally employ insulation rated for as...

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    DriveMotorBasics01.docPage 11 of 11Torque Above Base Speed0501001502002500306090120150180210240Frequency (HZ)% TorqueBase SpeedRated TorquePeak Torque1/N21/N

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