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Breakdown torque happens when ′ / and such that / and thus, with constant voltage input, a low-slip induction motor's percent-rated maximum torque is about half its percent-rated LRC. The relative stator to rotor leakage reactance of standard Design B cage induction motors is [ 57 ]
If two motors with the same and torque work in tandem, with rigidly connected shafts, the of the system is still the same assuming a parallel electrical connection. The K M {\displaystyle K_{\text{M}}} of the combined system increased by 2 {\displaystyle {\sqrt {2}}} , because both the torque and the losses double.
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.
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).
The machine thus starts as an induction motor until it approaches synchronous speed, when the rotor "pulls in" and locks to the stator field. [19] Reluctance motor designs have ratings that range from fractional horsepower (a few watts) to about 22 kW. Small reluctance motors have low torque, and are generally used for instrumentation ...
In the steady state, the electrical torque is equal to the mechanical torque and hence the accelerating power is zero. [1] During this period the rotor moves at synchronous speed ω s in rad/s. The electric torque T e corresponds to the net air-gap power in the machine and thus accounts for the total output power of the generator plus I 2 R ...
As an example, consider the use of a 10 hp, 1760 r/min, 440 V, three-phase induction motor (a.k.a. induction electrical machine in an asynchronous generator regime) as asynchronous generator. The full-load current of the motor is 10 A and the full-load power factor is 0.8. Required capacitance per phase if capacitors are connected in delta:
To obtain very quick torque control response in induction motor, it is required to suppress electromagnetic transients which might be caused by the control. Then it is necessary to investigate the electromagnetic transients of an induction motor. Within the induction motor, the largest inductance is the exciting inductance of exciting reactance.