## Motor Controls Training

Class Information
 Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
 Class Name: Acceleration Methods 385 Description: This class will describe the factors involved with motor acceleration and how they relate to each other. It will also explain how speed and acceleration are controlled in various types of electric motors. Difficulty: Advanced Number of Lessons: 14 Language: English, Spanish

Class Outline
• Objectives
• Motor Acceleration
• Motor Torque
• Locked Rotor Torque
• Pull Up Torque
• Breakdown Torque
• Horsepower
• NEMA Design
• Controlling Acceleration
• DC Motor Speed Control
• AC Motor Speed Control
• Summary

Class Objectives
• Describe motor acceleration.
• Describe motor torque.
• Define locked rotor torque.
• Define pull up torque.
• Define breakdown torque.
• Describe horsepower.
• Describe different types of motor loads.
• Describe NEMA motor design characteristics.
• Describe methods of controlling motor acceleration.
• Describe speed control in DC motors.
• Describe speed control in AC motors.

Class Vocabulary

Vocabulary TermDefinition
Another name for pull up torque. It is called accelerating torque because this is the moment at which speed transitions from starting speed to full speed.
The rate at which speed increases.
The speed (in rpm) at which the motor runs with full-line voltage applied to the armature and the field.
The maximum torque a motor can produce without abruptly losing motor speed.
A load that requires high torque at low speeds and low torque at high speeds. Horsepower remains constant as speed and torque are inversely proportional.
A load that requires a constant torque throughout acceleration. If the load needs to move faster, the horsepower is increased.
A power loss due to current flowing through wire. The lost power is converted into heat.
The voltage induced in the armature of a DC motor that opposes the applied voltage and limits armature current.
A measurement of the number of complete AC cycles that occurs in one second. Frequency is measured in Hertz (Hz).
The resistance to motion between the contact surfaces of two objects. Friction generates heat and increases the wear between components.
The torque needed to produce the rated power at the full speed of the motor.
A unit of power used to describe machine strength. One horsepower equals 33,000 ft-lbs of work per minute, or 746 watts.
The tendency of an object to stay in its state of rest or motion until acted on by an external force. Torque and braking must overcome inertia to accelerate or decelerate a motor.
The initial surge of current into the windings. Inrush current can be up to ten times higher than the continuously needed current because there is low initial resistance.
The torque that a motor produces when full power is supplied to the motor and the rotor is not yet moving.
The National Electrical Manufacturers Association. Motor nameplates carry NEMA letter designations that indicate the design characteristics of the motor.
The difference between a motor's synchronous speed and its speed at full load. Percent slip is a way to measure the speed performance of an induction motor.
The torque needed to cause a load to reach its full rated speed.
A continuously variable electrical resistor used to regulate current.
The external means of varying the speed of a motor under any type of load.
The ability of a motor to maintain its speed when a load is applied. A motor's speed regulation is fixed based on its design.
Another name for locked rotor torque. It can be called starting torque because it is the torque applied by the motor at startup.
The speed of the rotating magnetic field of an AC induction motor.
A force that produces rotation. Torque is measured in pounds-feet in the English system and Newton meters in the metric system.
A device that converts incoming 60Hz AC power into other desired frequencies to allow for AC motor speed control.
A load in which both torque and horsepower requirements can change depending on the needed speed.
A unit used to measure power. 746 watts equals one horsepower.