Amperes – A unit of electrical current, rate of flow of electrons. One volt across 1 ohm of resistance causes a current flow of 1 ampere.
Armature – The moving element in an electromechanical device.
AWG – American wire gauge.
Chorded Winding – A winding with a span less than full pitch.
Circuits – The number of conductors connected together for the purpose of carrying an electrical current. The number of paths current can flow through from one end of a phase.
Circular mil per Amp – Cross sectional area of conductor divided by the current (amps) in the conductor.
Class B insulation – insulation system rated by NEMA for maximum operation temperature of 130°C
Class F insulation – insulation system rated by NEMA for maximum operation temperature of 155°C
Class H insulation – insulation system rated by NEMA for maximum operation temperature of 180°C
Coil – Turns of wire used to produce magnetic flux or to react mechanically to a changing magnetic flux.
Coil Bottom Straight Length – The distance of the coils straight section which sits in the bottom of the slot, from the point where the coil begins to turn towards the knuckle to the point where the coil starts turning toward the knuckle beyond the other end of the stator core.
Coil Chord Factor – The ratio of the effective turns of a coil to the actual turns. Chord factor = Sin (90 x teeth spanned / {slots/pole})
Coil Connection End Extension – The distance from the stator iron to the outer edge of the coil knuckle on the connection lead side of the coil.
Coil Group – Coils that make up one pole of one phase (number of groups = phases x poles).
Coil Large Drop – Distance perpendicular to the core length and between the bore and the bottom end of the coil extension where the coil knuckle begins to take shape.
Coil Opposite End Extension – Distance from the stator iron to the outer edge of the coil knuckle on the coil side which has no leads.
Coil Small Drop – Distance (amount of clearance) perpendicular to the core length and between the bore and the top end of the coil extension where the coil knuckle begins to take shape.
Coil Throw (Pitch or Span) – Number of slots a coil spans, counting from the bottom side of a coil to the top side of the coil and including the slots that actually hold the bottom and top sides of the coil.
Coil Top Straight Length – Distance of the coils straight section which sits in the top of the slot just below the wedge, from the point where the coil begins to turn towards the knuckle to the point where the coil starts turning toward the knuckle beyond the other end of the stator core.
Coil Total Length – Overall coil length from the outer edge of one knuckle to the outer edge of the opposite knuckle should be measured while still in the stator core.
Concentric Winding – A winding in which each coil in a group of coils has a different span.
Conductor – Wire or combination of wires not insulated from one another, suitable for carrying an electric current through the transfer of orbital electrons.
Connection – The point of attachment of two or more component parts so that conduction can take place between them.
Core Back Iron – Distance between the bottom of the core slot and the outside diameter of the magnetic (steel) core (near the frame).
Core Bore Diameter – The inside diameter of a steel stator core. The distance from any point on the inside edge of the stator iron to a point diametrically opposite (180° around the inside of the bore).
Core Length – The length of a magnetic (steel) motor core. Length of the iron including vents but excluding the finger plates.
Core Slot Depth Under Wedge – Slot depth below wedge, space available for bottom coil, top coil and fillers.
Core Slot Width – Distance of slot measured between one core tooth and the next adjacent core tooth.
Corona – A discharge of electricity due to ionization of air appearing on the surface of a conductor when the potential gradient exceeds a certain value.
Corona Protection – Conductive tape or conductive paint intended to equalize voltage stress between the iron core and the coil thus preventing corona discharge from occurring.
Current – The movement of electrons through a conductor, measured in amperes.
Delta Connection – Three phase winding connection in which the phases are connected in series to form a closed circuit. Triangular like terminal connection in a three-phase system. Three-phase winding in which the ends of a given phase are each connected to the end of another different phase.
Edge Wound – Coil wound on the edge (on the width) of the rectangular shaped conductor rather than on the flat side (on the thickness) of the rectangular shaped conductor. The conductor is typically ribbon like (very wide as compared to its thickness).
Finger Plates – Plates of heavy metal that apply pressure to the stator laminations.
Formed Wound Coil – A coil wound and shaped before being placed in the stator or armature of a motor or generator.
Frequency (f) – The number of complete cycles in one second of alternating current or voltage waves expressed in hertz.
Hertz (Hz.) – A unit of frequency equal to one cycle per second.
Horse Power (hp.) – Unit of power, or capacity of mechanism to do work. One horse power equals 746 watts.
Kilovolt-Ampere (KVA) – Apparent power in an ac circuit containing reactance. Voltage multiplied by amperes without consideration of phase.
Kilowatt (Kw.) – A unit of electrical power. Output rating of motor. 1,000 watts.
Lap Winding – A winding in which all coils have the same span.
Left Hand Coil – Facing the coil connection side of the unit the top coil side is on your left.
Magnetic Induction – Also called magnetic flux density. The flux per unit area perpendicular to the direction of the flux.
Motor – A rotating machine that converts electrical power into mechanical power.
Phase (Φ) – The number of separate voltage waves in an alternating current supply.
Right Hand Coil – Facing the coil connection side of the unit the top coil side is on your right.
R.P.M. – Revolutions per minute.
Rotor – The rotating element of any motor or generator.
RTD – Resistance temperature detector.
Skewed Slot – Core slots which are not parallel with the shaft.
Stator – The stationary part of a rotating electric machine.
Support Ring – Ring which purpose is to mechanically support the coil extensions.
Total (Overall) Core Slot Depth – Distance from the top of the core tooth to the bottom of the slot.
Total Wires in Parallel (Wires in Hand) – Total conductor strands for each coil turn, the wires brought out together in one single coil lead.
Transposition – The inversion of the conductor at one or more places typically in the end portion of a coil. A transposition reduces losses and heat due to circulating currents that result in non-uniform current distribution in a conductor.
Turns per Coil – The number of times the conductor is looped into a coil. (Wires in cross section / wires in parallel {in hand}).
Voltage – (E.) electromotive force. Effective difference of potential between any two conductors. Electric pressure that exists between two points. The force which causes current to flow through an electrical conductor.
Watt (W.) – Unit of electric power required to do work at a rate of 1 joule per second. There are 746 watts in 1 horsepower.
Winding – A conductive path inductively coupled to a magnetic core.
WYE Connection – Y shaped winding connection also called a star connection. Three-phase winding in which one end of each phase is connected together to make a “star” point. The other ends are connected to the power source.