Definitions

Definitions

Here is a list of definitions and terms that you'll more than likely run into within our industry. Hopefully these terms will help you understand any communications you might have with our technicians and other employees.

ABCDEFGHIJKLMNOPQRSTUVWXYZ

A

AC - Shortened term for "alternating current". Current flows in both + and - directions

Acceleration Time - The time required for a motor to reach full speed from standstill (zero speed) position.

Accelerating Torque - The torque developed from standstill (zero speed) to full speed at nameplate voltage. Sometimes the term "Net Accelerating Torque" is used to mean the excess motor torque capability over the torque for the attached load.

Alternating Current - Type of electrical circuit that changes polarity at regular intervals; The commonly available electric power supplied by an AC generator and distributed in one, two, and three phase form.

Amortisseur Winding - A small damper winding designed to start a synchronous motor

Ambient Temperature (Amb.) - Ambient Temperature is the temperature of the medium, such as air, water or earth, into which the heat of the equipment is dissipated.
For self-ventilated equipment, the ambient temperature is the average temperature of the air in the immediate neighborhood of the equipment.
For air or gas cooled equipment with forced ventilation, or secondary water cooling, the ambient temperature is taken as that of the in coming air or cooling gas.
For self-ventilated enclosed (including oil immersed) equipment, considered as a complete unit, the ambient temperature is the average temperature of the air outside of the enclosure in the immediate neighborhood of the equipment.
Most motors are designed to operate in an ambient not over 40°C (104°F).
Note: A rating of 40°C Ambient is not the same as a rating of 40°C Rise; see Temperature Rise.

Ampere - Unit of electrical current

Armature - Rotating portion of a DC electric motor

B

Bearing - Sleeve, ball, roller; supports a load and allows the load to move freely with minimal friction

C

Compound - Type of DC electrical winding combining both a Shunt and Series field

Contactor - A contactor is designed for the specific purpose of establishing or interrupting a power circuit.

D

DC - Direct Current. The type of power from a battery. Current flows in only ONE direction

E

Enclosure - A housing or "box" to cover sensitive items from mechanical or environmental elements

Encoder - A device that translates movement (angular or linear) into an electrical signal

F

Frame - The outside (protective) portion of an electric motor that contains the stator laminations and the electrical windings of the motor

G

GUI - Graphical User Interface. (Pronounced: GOO-ee). A human readable depiction of computer program data

H

Hertz - Unit of alternating current indicating how often it changes polarity. Previously referred to as "Frequency"

Hysteresis - The lag in response exhibited by a body in reacting to changes in the forces, especially magnetic forces, affecting it.

I

Interpole - An additional coil in a DC motor, in series with the armature circuit, which helps reduce "arcing" of he brushes and aids in "commutation".

J

Junction Box - A box (usually metal) into which the power wires from a power source are connected.

K

Kinetic - Characterized by movement. Kinetic energy is the energy of a mass in motion.

L

Leads - The wires exiting out of the motor terminal box used to connect the motor and/or accessories to the power supply.

Line Voltage - Voltage supplied by the power company or voltage supplied as input to the device.

Linear Acceleration/Deceleration (LAD) - A Circuit that controls the rate at which the motor is allowed to accelerate to a set speed or decelerate to zero speed. On most drives, this circuit is adjustable and can be set to accommodate a particular application.

Linearity - The measure of the maximum deviation between the actual speed and the set speed, expressed as a percentage of set speed.

Locked-Rotor Current - The steady-state current taken from the line with the rotor locked and with rated voltage (and rated frequency in the case of alternating-current motors) applied to the motor.

Locked-Rotor Torque - (Static Torque) The locked-rotor torque of a motor is the minimum torque which it will develop at rest for all angular positions of the rotor, with rated voltage applied at rated frequency.

Long Shaft Motor - NEMA standard MG-1 defines shaft length as the dimension AH, or the distance from the face, flange or base of the machine to the end of the shaft. In a standard type "T" frame the NEMA standard shaft extension (long shaft) is supplied. It is normally used where overhung loads from pulleys, sheaves and sprockets are encountered.

M

Magnetic - Having the properties of a magnet. Capable of being magnetized by a magnet.

Magnetic Polarity - It is a fundamental principle of winding that adjacent poles must be wound to give opposite magnetic polarity. This does not mean that the coils actually have to be wound in this direction before being placed into the stator. It does mean that the winding must be connected so that, if the current proceeds through one pole in a clockwise direction, it must proceed through the next pole in a counterclockwise direction. This principle is used to determine the correctness of connection diagrams.

Marine Duty Motor - A specialized motor designed for use onboard ships. Motors are designed per IEEE 45 motor specification.

Master Drive - A drive that sets the reference for one or more follower drives.

Mechanical Degree - The popular physical understanding of degrees (360 degrees = 1 revolution).

Megohmmeter - A device used to measure an insulation system's resistance. This is usually measured in megohmmeter and tested by passing a high voltage at low current through the motor windings and measuring the resistance of the various insulation systems and tested by passing a high voltage at low current through the motor windings and measuring the resistance of the various insulation systems.

Modular Construction - The major circuit elements are mounted in replaceable modules which can readily be removed and replaced. Equipment can be serviced without delay.

Module - A unit of circuit elements usually packaged so it can be readily replaced.

Motor Constant - The ratio of motor torque to motors input current (motor torque per amp).

Mounting (Mtg.) - Basic types:

1. Bolted * Motor is attached to frame with removable bolts.

2. Rigid * Motor solidly fastened to equipment through metal base that is welded, bolted, or cast into the metal shell or clamped to the end shield hubs.

3. Cradle/Resilient (Res.) * Motor shell isolated from base by vibration absorbing material, such as rubber rings on the end shields, to reduce transmission of vibration to the driven equipment.

4. Face or Flange * Shaft end has a flat mounting surface, machined to standard dimensions, with holes to allow easy, secure mounting to driven equipment. Commonly used on pumps, oil burners and gear reducers.

5. Stud * Motor has bolts extending from front or rear, by which it is mounted. Often used on small, direct-drive fans and blowers.

6. Yoke * Tabs or ears are welded to motor shell, to allow bolting motor to a fan column or bracket.

Multi-Motor Operation - A system in which one controller operates two or more motor simultaneously, maintaining a constant ratio between the speeds of the motors.

Multi-Speed Motor - An induction motor that can obtain tow, three, or four discrete (fixed) speeds by the selection of various stator winding configurations.

Mush Wound Coils - Also called random wound coils - Where the turns are wound without definite placement, or, at random. Most small motors up to 25 HP are mush wound although motors up to 150 HP have been successfully wound without formed coils. The limit is not the horsepower, but did the manufacturer allow enough slot space for the wasteful, random wound coil.

N

NEC - The National Electrical Code is the recommendation of the National Fire Protection Association and is revised every three years. City or state regulations may differ from these code regulations and take precedence over NEC rules.

NEMA (National Electrical Manufacturers Association) - A non-profit organization organized and supported by manufacturers of electrical equipment and supplies. Some of the standards NEMA specifies are horsepower ratings, speeds, frame sizes and dimensions, and torques and enclosures.

Negative Feedback - A condition where feedback is subtractive to the input reference signal. Negative feedback forms the basis for automatic control systems.

Negative Torque - A torque developed in opposition to the normal torque of the motor. This may occur at starting (common to 2 pole motors) or at some speed below nameplate RPM. This causes "cusps" or "saddles" in the graphed torque curves.

NEMA Design A Motors - Classification of motors by NEMA used on machines such as fans, blowers, pumps and compressors, requiring relatively low starting torque followed by increasing torque with increasing speed up to the full-load speed and torque. Design A motors are differentiated from design B motors by a higher locked-rotor current.

NEMA Design B Motors - Classification of motors by NEMA used on machines such as fans, blowers, pumps and compressors, requiring relatively low starting torque followed by increasing torque with increasing speed up to the full-load speed and torque. This is the most popular motor design.

NEMA Design C Motors - Classification of motors by NEMA used on machines such as reciprocating air compressors and conveyors, requiring relatively high starting torque that is normally greater than the torque required at full-load speed.

NEMA Design D Motors - Classification of motors by NEMA used on machines that impose pulsating loads or require frequent starting of the motor, such as punch press, oil well pumping, and hoist applications.

NFPA - National Fire Protection Association. The group that prepares and published the National Electric Code, Hazardous Chemicals, and numerous other such publications.

No Load - The state of a machine rotating at normal speed under rated conditions, but when no output is required from it.

O

ODP - Open Drip Proof - A description of a type of electric motor enclosure where the motor case has openings allowing the internal fan to exhaust warm air out of the frame.

P

Phase - A term, which indicates the space relationships of windings, and changing values of the recurring cycles of AC voltages and currents. Due to the positioning (or the phase relationship) of the windings, the various voltages and currents will not be similar in all aspects at any given instant. Each winding will lead or lag another, in position. Each voltage will lead or lag another voltage, in time. Each current will lead or lag another current, in time.

Q

QS 9000 - Automotive Duty Quality Specification

R

Resistance - The property of a conductor by virtue of which the passage of current is opposed, causing electric energy to be transformed into heat; Equal to the voltage across the conductor divided by the current flowing in the conductor: Usually measured in ohms. R = E/A

S

Series - In line with. Assume we have three wires; A1-A2, B1-B2, and C1-C2. If we connect A2 to B1, and B2 to C1, then it is said that A1 to C2 is a set of wires connected in "series"

Shunt - To divert (a portion of current) by connecting a circuit element in parallel with another.

Stepper - A motor whose rotational movement is in equal "steps" or degrees of rotation.

Synchronous - To be operating in unison

T

TEAO - Totally Enclosed Air Over. A description of a type of electric motor enclosure where the motor case is cooled by the air flowing OVER the outside of the case.

TEBC - Totally Enclosed Blower Cooled. A description of a type of electric motor enclosure where the motor is cooled by a separately powered "blower".

TEFC - Totally Enclosed Fan Cooled. A description of a type of electric motor enclosure that has an external fan attached to the opposite drive end of the shaft that forces cooling air over the motor frame.

Temperature Rise - The measurable rise above the ambient temperature at which the fully loaded motor operates. This temperature rise is the result of the heat losses in the stator winding, core, and rotor. On most motors, manufacturers have replaced the Rise rating on the motor nameplate with a listing of the Ambient temperature rating, insulation class and service factor.

U

UL Component Recognition - A classification by Underwriter's Laboratories which recognizes the components of a given product meet UL standards, although the actual finished product may not be UL listed.

UL Listed Product - A classification by Underwriter's Laboratories for equipment which met certain evaluations of concern as determined by UL.

Under-voltage Protection - Under-voltage or low voltage protection is the effect of a device, operative on the reduction or failure of voltage, to cause and maintain the interruption of power to the main circuit. The main objective of the device is to prevent restarting of the equipment on an under-voltage condition.

V

Voltage - A unit of electrical potential. Without VOLTAGE, current would not flow in a wire.

W

Watt - The unit of POWER in the International System of Units. It is the ELECTRICAL WORK done when 1 ampere flows across a potential of 1 volt.

WYE - A type of electrical connection that when viewed in diagrammatic form is the shape of a "Y".

X

Y

Z

Zero Speed Switch - A motion sensing switch that is used to prevent the motor from being plugged while the motor shaft is in motion.