Performance estimation method for in-service single-phase induction motors
This paper proposes a performance estimation method for single-phase induction motors in the field at any operating load using a set of data from in-service measurement. This paper describes the use of the improved equivalent circuit models based on double-revolving-field theory which a core loss element is properly added in order to provide more accurate results. The appropriate values for the model parameters can be evaluated by the use of measured data coupled with the genetic algorithms. The estimated performance result of several motors are presented and then compared to the measured values obtained from load tests, and clearly illustrate that agreement between the proposed method and the actual one is good.
A study of methods to measure the parameters of single-phase induction motors
Two methods for the experimental determination of single-phase induction motor parameters are studied. The one is a relatively complicated method based on single-phase measurements. The other utilizes a two-phase based strategy. An investigation was done to evaluate the accuracy with which the performance of a machine can be predicted using experimentally determined numerical values for the machine parameters, calculated from these two methods. Comparing the two sets of calculated performance values, shows that the two-phase method gives a better correlation with the measured values than the single-phase method. >
Experimental study on ground vibration of blasting the boulder with tandem shaped charging warhead
Hazardous effects of blasting the boulder with the new breaking-blasting equipment-tandem shaped charging warhead are mainly air shock wave, seismic wave and blast slung shot. Blast-induced ground vibration is one of the inevitable effects and may cause substantial damage to nearby structures. Started from the formation process and mechanism of ground vibration to study the seismic wave, the research attained curve of vibration velocity of monitoring points by TC-4850 and carried out differential and fast Fourier transform analysis of the curve. And the results concluded that blasting vibration with tandem shaped charging warhead mainly comes from prime charge; the attenuation law can be predicted by Sadev’s Formula. Explosion vibration frequency range is 20-150 Hz, while with the increase of distance from the blasting center, blasting vibration intensity attenuates rapidly, vibration duration increases and vibration frequency gradually reduces. Compared with general rock blasting, its attenuation rate of blasting vibration is faster with higher frequency and smaller impact on buildings, but the harm effects should not be ignored for the special application environment.