The classification of electrical fault

According to the composition characteristics of electrical devices,from looking for electrical fault,from the viewpoint of the common electrical fault can be divided into three categories: 1.The power failure: lack of power,voltage,frequency deviation,the polarity of by phase line and neutral line and reverse,the lack of a power supply,phase sequence change,ac/dc mixed.2.The circuit fault: break,electric vehicle motor short circuit,short,grounding,connection error.3.The equipment and component failure: overheating burned,can not run,electrical breakdown,performance becomes worse.According to the fault phenomena analysis the cause of the problem,the key is to find electrical fault.Is based on the analysis of the basic theory of electrician,is for the electrical device structure,principle,performance,fully understand,ac electric motor is with the combination of the actual fault.


The causes of an electrical fault may be a lot of,it is important to find out the main reason in many reasons,and use approach to troubleshooting.For example,a three- phase cage asynchronous motor fault functioning,whatever the case,is the most concentrated performance motor does not work,but is not necessarily in the motor fault,and may be a power failure,may also be the failure of circuit or equipment and components.That is to say,the same failure form,failure of a variety of reasons.In these reasons,which is what reasons make the motor can't work,even after a deeper and more detailed analysis.For example: if the motor is used for acmotortrading.blogspot.com the first time,it should check power supply,circuit,the motor and load analysis; If the motor is used for the first time after repair,it should start from the motor itself check analysis; If the motor is running for a period of time suddenly can't run,it should check points off power supply and control components.Through the above process,then determine the specific cause of motor fault.

Ac motor

To realize the mechanical energy and electrical energy transformation of mini electric motor mechanical communication. Ac motor is the most commonly used motor. Due to the status of the motor can pass, the same motor as a generator and motor. Ac motor according to the varieties could be divided into two types: synchronous motor and induction motor. Synchronous motor rotor rotational speed n s the same as the rotating magnetic field rotation speed, is called the synchronous speed. N s and pick up the frequency of the alternating current polarity logarithmic relationship between p and f motor for n s = f/p. In China, the power frequency 50 hz, so two pole motor synchronous speed is 3000 RPM, quadrupole motor synchronous speed is 1500 RPM, and so on. The speed of the rotor asynchronous motor is wholesalemotor.blogspot.com always less than or more than the speed of the rotating magnetic field, the difference between the two (called slip) usually within 10%. 

The speed of the ac motor (either synchronous or asynchronous) the restriction of the power frequency, and speed control is difficult. Ac motor generally adopts three-phase system, because of the three-phase ac motor compared with the single phase motor, no matter in such aspects as performance index, raw material use and price has obvious advantages. Large capacity synchronous motor are turning pole type, namely the rotor magnetic pole, is produced by passing a dc excitation winding, and synchronous machine very logarithm is the logarithmic rotor magnetic pole. Eight pole motor rotor is eight pole, 2 p = 8, namely the motor with 4 poles. Steam turbine generator is non-salient pole Dongfeng Electric type motor, more commonly a logarithmic rarely, generally for 1, 2, and n = 60 f/p, so his speed is high, up to 3000 RPM (frequency), and the number of considerable ac electric motor hydro-generator, for salient pole rotor structure, the process is more complex, because the number of his lot, so he has a very low speed, maybe only a few turns per second.

Brushless synchronous generator is how to generate electricity?

Three-phase brushless synchronous generator excitation system are connected by a coaxial communication issue of ac exciter,after rotating rectifier rectifier for direct current (dc), Then sent to the generator exciting winding. Ac exciter is rotating armature type of three-phase medium frequency generator,the gasoline generator spare partsfrequency of three phase generator generator frequency three times Left and right sides,which can wholesalemotor.blogspot.com improve the excitation response speed. Exciting winding is stationary,controlled by the automatic voltage regulator AVR excitation. Rotating rectifier Have high reliability,using the three-phase half wave bridge rectifier and three-phase full-wave bridge rectifier,firmly fixed on the rotor,with the current measurement And fault indicating device.

How to change the direction of rotation of three-phase motor

Direction of the rotation of the rotor of the motor is determined by the direction of rotation of the

asynchronous motor stator rotating magnetic field established,and the direction of

the rotating electricalmotor1.blogspot.com magnetic field with the three phase

current phase sequence.This www.facebook.com/guohong.trading changed the current

phase sequence that change the direction of the rotating magnetic field,synchronous

motorwhich changed the direction of rotation of the motor.