- Settore: Electrical equipment
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Is arranged for starting by first energising part of the primary winding and subsequently energising the remainder of this winding in one or more steps. The purpose is to reduce the initial value of the starting current drawn or the starting torque developed by the motor. A standard part winding start induction motor is arranged so that one-half of its primary winding can be energised initially and subsequently the remaining half can be energized, both halves then carrying the same current.
Industry:Electrical equipment
A motor with magnets embedded into the rotor assembly, which enable the rotor to align itself with the rotating magnetic field of the stator. These motors have zero slip (constant speed with load) and provide higher torque, efficiency and draw less current than comparable reluctance synchronous motors. See (HYSTERESIS SYNCHRONOUS)
Industry:Electrical equipment
Indicates the space relationships of windings and changing values of the recurring cycles of A.C. 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. The most common power supplies are either single (10) or three phase (with 120 electrical degrees between the 3 phases).
Industry:Electrical equipment
Reconnecting a motor's winding in reverse to apply a reverse braking torque to its normal direction of rotation while running. Although it is an effective dynamic braking means in many applications, plugging produces more heat than other methods and should be used with caution .
Industry:Electrical equipment
A ratio of a one-minute meggar test (see Meggar Test) to ten-minute meggar test. Used to detect contaminants in winding insulation done typically on high voltage, V.P.I. motors which are tested by water immersion.
Industry:Electrical equipment
In an AC motor, refers to the number of magnetic poles in the stator winding. The number of poles is a determinant of the motor's speed.
In a DC motor, refers to the number of magnetic poles in the motor. Creates the magnetic field in which the armature operates. (Speed is not determined by the number of poles).
Industry:Electrical equipment
Two or three-phase induction motors have their windings, one for each phase, evenly divided by the same number of electrical degrees. Reversal of the two-phase motor is accomplished by reversing the current through either winding. Reversal of a three-phase motor is accomplished by interchanging any two of its connexions to the line. Polyphase motors are used where a polyphase (3-phase) power supply is available and is limited primarily to industrial applications.
Starting and reversing torque characteristics of polyphase motors are exceptionally good. This is due to the fact that the different windings are identical and, unlike the capacitor motor, the currents are balanced. They have an ideal phase relation which results in a true rotating field over the full range of operation from locked rotor to full speed.
Industry:Electrical equipment
Identifies the type of power supply providing power to a DC motor. Frequency, voltage, and type of rectifier configuration.
Industry:Electrical equipment
A measurement of the time phase difference between the voltage and current in an AC circuit. It is represented by the cosine of the angle of this phase difference. For an angle of 0 degrees, the power factor is 100% and the volt/amperes of the circuit are equal to the watts. (This is the ideal and an unrealistic situation.) Power factor is the ratio of Real Power-KW to total KVA or the ratio of actual power (watts) to apparent power (volt-amperes).
Industry:Electrical equipment
That winding of a motor, transformer or other electrical device which is connected to the power source.
Industry:Electrical equipment
