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It is also known as short-circuit test (because it is the mechanical analogy of a transformer short-circuit test), [1] locked rotor test or stalled torque test. [2] From this test, short-circuit current at normal voltage , power factor on short circuit, total leakage reactance , and starting torque of the motor can be found.
9 starting voltage tap connections allowing for ± 5% variation of starting torque around NEMA recommended taps at 50%, 65% and 80%. This allows the selection of motor starting torque to be closely matched with the driven load requirements. Selection is by means of the connection links between the winding sections.
is the motor torque constant (SI unit, newton–metre per ampere, N·m/A), see below If two motors with the same K v {\displaystyle K_{\text{v}}} and torque work in tandem, with rigidly connected shafts, the K v {\displaystyle K_{\text{v}}} of the system is still the same assuming a parallel electrical connection.
By adjusting the shape of the bars in the rotor, the speed-torque characteristics of the motor can be changed, to minimize starting current or to maximize low-speed torque, for example. Squirrel-cage induction motors are very prevalent in industry, in sizes from below 1 kilowatt (1.3 hp) up to tens of megawatts (tens-of-thousand horsepower).
A motor soft starter is a device used with AC electrical motors to temporarily reduce the load and torque in the powertrain and electric current surge of the motor during start-up. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power cables and electrical distribution network ...
This imparts sufficient rotational field energy to start the motor. These motors are typically used in applications such as desk fans and record players, as the required starting torque is low, and the low efficiency is tolerable relative to the reduced cost of the motor and starting method compared to other AC motor designs.
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Torsion of a square section bar Example of torsion mechanics. In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. [1] [2] Torsion could be defined as strain [3] [4] or angular deformation, [5] and is measured by the angle a chosen section is rotated from its equilibrium position. [6]