lesson 3-5 Flashcards
the rotating part of the motor
armature
It is constructed from an iron cylinder that has slots cut into it. Wire is wound through the slots to form the windings. The ends of the windings are connected to the commutator, which consists of insulated copper bars and is mounted on the same shaft as the windings.
The windings and commutator together form the ______
armature
is the winding (or set of windings) of anelectric machine
armature
Types of DC Servo motor
Permanent Magnet
Series
Shunt
Compound
usesa magnet to supply field flux. ____________ DC motors have excellent starting torque capability with good speed regulation. A disadvantage of _________ DC motors is they are limited to the amount of load they can drive. These motors can be found on low horsepower applications.
Another disadvantage is that torque is usually limitedto 150% of rated torqueto prevent demagnetization of the ____________.
Permanent Magnet DC Motors
motor the field is connected in series with the armature.The field is wound with a few turns of large wire because it must carry the full armature current.
series DC motor
the motor develops alarge amount of starting torque. However, speed varies widely between no load and full load. Series motors cannot be used where a constant speed is required under varying loads.
series motors
generally are not suitable for use on most variable speed drive applications.
Series-connected motors
motor the field is connected in parallel with the armature windings. The ___________ motor offers good speed regulation. The field winding can be separately excited or connected to the same source as the armature.
The advantage to a separately excited _______ field is the ability of a variable speed drive to provide independent control of the armature and field
Shunt motors
the supply is given separately to the field and armature windings. The main distinguishing fact in these types of DC motor is that, the armature current does not flow through the field windings, as the field winding is energized from a separate external source of DC current.
Separately excited
have a field connected in series with the armature and a separately excited shunt field.
The series field providesbetter starting torqueand the shunt field providesbetter speed regulation.
Compound motors
A type of servomotor that uses AC electrical input in order to produce mechanical output in the form of precise angular velocity is known as __________.
AC SERVOMOTOR
servomotors are basically two-phase induction motors with certain exceptions in designing features.
AC SERVOMOTOR
The output power achieved from ac servomotor ranges between some
watt to a few hundred watts
AC Servo motor the operating frequency range is between
50 to 400 Hz
are basically two-phase squirrel cage induction motors and are used for low power applications. Nowadays, three phase squirrel cage induction motors have been modified such that they can be used in high power servo systems.
AC SERVOMOTOR
The main difference between a standard split-phase induction motor and AC motor
is that the squirrel cage rotor of a servo motor has made with thinner conducting bars, so that the motor resistance is higher.
two distinct types of AC servo motors
- SYNCHRONOUS-TYPE AC SERVO MOTOR
- INDUCTION-TYPE AC SERVO MOTOR
consist of stator and rotor. The stator consists of a cylindrical frame and stator core. The armature coil wound around the stator core and the coil end is connected to with a lead wire through which current is provided to the motor.
SYNCHRONOUS-TYPE AC SERVO MOTOR
The rotor consists of a permanent magnet and hence they do not rely on AC induction type rotor that has current induced into it. also called as brushless servo motors because of structural characteristics.
SYNCHRONOUS-TYPE AC SERVO MOTOR