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Motor Testing
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
Locked rotor tests are used to determine the starting torque and current of electric motors, which are the two main indicators for assessing motor performance. In this testing method, the testing motor is loaded to the maximum limits by applying maximum current to a hysteresis or powder brake type of a dynamometer or by mechanically holding the rotor shaft from turning and energizing the stator. The voltage supplied to the stator is reduced to prevent stator winding overheating. At the rotor-locking condition, the motor operation parameters such as torque, current, and voltage are measured and displayed. Sometimes, the locked rotor test is also called stalled torque test or blocked rotor test.
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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
blocked-rotor test an induction motor test conducted with the shaft held so it cannot rotate. Typically about 25% of rated voltage is applied, often at reduced frequency and the current is measured. The results are used to determine the winding impedances referred to the stator. blocking state entered if a new user finds all channels or access mechanisms busy and hence is denied service. Generally accompanied by a busy signal. The call blocking probability may be given by the Erlang B or Erlang C formula. See also adequate service, multiple access interference. blocking artifact the visibility in an image of rectangular subimages or blocks after certain types
The Squirrel-Cage Induction Motor Model and Its Parameter Identification Via Steady and Dynamic Tests
Published in Electric Power Components and Systems, 2018
Onofre A. Morfín, Carlos E. Castañeda, Riemann Ruiz-Cruz, Fredy A. Valenzuela, Miguel A. Murillo, Abel E. Quezada, Nahitt Padilla
For the purposes of this research, parameter identification of the squirrel-cage induction motor model is made with off-line dynamics and steady-state tests via an acquisition board to determine both electrical and mechanical parameters. The measurement of the DC resistance of the stator winding, no-load test, and blocked-rotor test is applied to induction motor to identify the equivalent circuit model. In addition, we have made the synchronous velocity test to obtain a good approximation of the core loss and calculate the friction loss from the rotational loss. In each one of the tests mentioned, voltage and current measurements of all phases are taken for including any electric unbalance in the stator winding; while, the average power is calculated with very good accuracy by filtering the instantaneous three-phase power. A dynamic test is made when the motor is turned-off and a vector of the velocity fall is captured to obtain an approximate value of the inertial moment Jm using the friction coefficient Bm which is obtained from the consumed power before de-energizing the motor.
Teaching Synchronization of Synchronous Generator Using Virtual Laboratory
Published in IETE Journal of Education, 2023
Arif Iqbal, Girish Kumar Singh
With the creation of virtual tests, physical and economic limits in the teaching–learning process are overcome to some extent. A very less literature is available that suggests to incorporate the simulation tools in teaching–learning process of undergraduate electrical machinery courses. In Ref. [4], a method to conduct different tests of a single-phase power transformer was described, which includes open-circuit test, short circuit test, load test, and short-heat run test. Virtual testing (no-load and blocked-rotor test) was investigated on a three-phase induction motor [5], and circle diagram was developed [6]. Concept of web-based virtual laboratory was used to perform experiment on synchronous machine, highlighting a controlled operation in motoring mode, and some tests (no-load test and blocked-rotor test) in generating mode [7]. But an extensive exploration of synchronous machine in an interconnected system, using user-friendly simulation tools for an improved teaching–learning process, has not been reported so far. Therefore, the major contribution of this paper is to teach the synchronization of synchronous generator with running alternator using a virtually developed simulation model on MATLAB/Simulink platform. The concept of virtual laboratory has been further extended to motivate the students for further research work, for which the performance improvement has been shown in synchronization processes of test machine by using a closed loop speed control scheme of prime mover. Implementation of a closed loop control scheme on virtual platform will be certainly beneficial for further learning, particularly for final year students and young researchers.
MATLAB Simulation of Circle Diagram in Three Phase Induction Motor
Published in IETE Journal of Education, 2022
For blocked rotor test, we define Is = Short circuit current or full load current at blocked rotor condition,Vs = Line voltage (reduced value) during blocked rotor,Ws = Short circuit power input during blocked rotor test,and cos Φs = power factor at the short circuit