Three-phase asynchronous motor winding short circuit

Due to poor welding or use corrosive flux,have not cleared after welding,it may cause a pot of welding or loose;Subjected to mechanical stress or collision coil short circuit,also can make the wire burned,short circuit and earth fault in a couple of wire and burn a single or a few wire short circuit,several other wire due to the increase of current temperature rise,cause heating winding and open circuit.Generally fall into one phase winding end disconnection,turn-to-turn short circuit,parallel branch circuit,wire and burn more of a single circuit,rotor broken cage.Fault phenomenon: 1.The motor can't start,unbalanced three phase current,there are abnormal noise or vibration,temperature rise more than permitted or smoke.2.Reasons: (1) during overhaul and maintenance touch off or manufacturing quality problems.,(2) winding each element (phase) group and the 5kw permanent magnet generator winding and fixture wire connection head welding,sealing off long running overheating.(3) by the mechanical force and electromagnetic force make winding damage or pulled apart or cause drag mark.(4) or interphase short circuit and grounding caused winding coils badly burned or fuse,etc.

3.Check the method: (1) the method of observation.Breakpoint most occurred in winding ends,look have without touch fold,joint the presence of desoldering.(2) a multimeter.Using resistance,to "Y" type of connection to connect a table bar in the center of the "Y" shape,the other in turn in the head end of the electric motors price three-phase winding,infinite phase has a breakpoint;"Delta" connection type of short connection,measuring winding in each group respectively,infinity to breaking point.(3) test lamp.Method with former,such as bright a photograph for open circuit.(4) megohmmeter.Resistance tends to infinity (that is,not as a zero value) is the cut-off point.(5) current meter method.Motor at runtime,use current meter to measure three phase current,if the imbalance of three phase current and short-circuit phenomenon,and no is a phase winding is part of the current small short circuit fault.(6) bridge method.A phase when the motor is bigger than the other two phase resistance,resistance show that the phase winding part of open circuit fault;(7) the current balance method.For "Y" type of connection,but after the three-phase winding parallel,alternating current into the low voltage large current,if the current in the three-phase winding is greater than 10%,one end of the small current for the circuit;For "delta" connection type,the stator winding of a contact apart first,then by interlinked into low voltage high current,wholesalemotor.blogspot.com one of the small current for open circuit.(8) broken cage detector test.Check,if the broken rotor cage millivoltmeter readings should be reduced.

4.Open circuit processing method: (1) open circuit in the end,the connection after welded,set of insulating tube,with insulation material and good binding,dry again.(2) the winding due to interturn,interphase short circuit and grounding,etc and cause severe charred generally should change new windings.(3) to the breaking point in the slot,belong to a few breakpoints for single phase asynchronous motor emergency treatment,the grouping elimination method is adopted to find the breakpoint,and broken in winding connection and the insulation used after qualified.(4) can be used for broken squirrel-cage rotor cage welding,cold connection or change the original repair.

Cascade speed regulation method

Cascade speed regulation refers to the motor rotor winding circuit in series motor vehicle spare partswith adjustable additional potential to change the slip of the motor,to achieve the purpose of speed control.Most of the slip power is absorbed by series of additional potential to recycle produce additional device,the absorption of 12 volt electric motor returning the slip power grid or conversion of energy use.According to the slip power utilization way,cascade speed regulation can be divided wholesalemotor.blogspot.com into motor cascade speed regulation,mechanical cascade speed regulation and thyristor cascade speed regulation form,adopts thyristor cascade speed regulation electrical motor.

 Its characteristic is: to speed the slip loss in the process of feedback to the grid or production machinery,high efficiency;Installed capacity is proportional to the speed range,the investment province,apply to speed range in production machinery from 70% to 90% of the rated speed;Speed regulating device failure can switch to run at full speed,avoid production;Thyristor cascade speed regulating power factor is low,the influence on harmonic.This method is suitable for the fan,water pump and the rolling mill,mine hoist,the extrusion machine use.

The classification of ac contactor purposes

Contactor is a kind of automation control of electrical appliances.Contactor is mainly used for frequent connected or mini electric motor diplomatic relations,dc,has a large capacity of control,remote operation,relay can realize timing operation and interlock control,all kinds of quantitative control and the pressure loss and under-voltage electric motors 12 volt protection,widely used in automatic control circuit,the main control object is motor,can also be used to control other electric power load,such as electric heaters,lighting,electric welder,capacitor Banks,etc.Contactor can be divided by accused of current type ac contactor and dc contactor.Here introduces the commonly used ac contactor.Communication ac electric

motor can be divided into the electromagnetic contactor and vacuum type two kinds.

Combination switch with low voltage circuit breaker recognition application

Appliances that can signal or request according to the outside world, manually or automatically switched on or off circuit, the circuit parameter, intermittent or continuous change to switch circuit or single phase induction motor non-electric object, control, protection, detection and adjustment of electrical devices or equipment. Low voltage electrical appliances are usually refers to working in the rated ac voltage up to 1200 v or dc voltage below 1500 v circuit of electrical appliances. Low voltage apparatus single phase generator according to the basic use commonly divided into two categories, distribution appliances and control electronics. Distribution appliances mainly include the combination switch, low voltage circuit breaker, fuse, transformer; Control appliances including contactor, relay and the main electrical appliances (including the button, trip switch, switch). 

Low voltage electrical classification method: according to www.dongfeng-motor.com the operation mode can be divided into manual and automatic electrical appliances; According to the principle of work is divided into electromagnetic appliances and non-electricity control electronics; According to a non-contact divided into contact electrical appliances, non-contact electric and hybrid electric appliance; According to the electrical configuration is divided into a single electrical appliances and complete set www.facebook.com/dongfeng.motors of electrical appliances; Industrial electrical appliances, chemical by using occasions are divided into general electric, mine electrical, traction electric appliance, aviation, Marine, electrical appliances, etc. Combination, combination switch. Switch is often used as a switch, but also in the electrical control circuit used as isolating switch, not frequently switched on and points out the role of electrical control circuit.

The choice of single-phase capacitor electric mechanical and electrical capacity

The choice of single-phase capacitor small electric fan motor electric mechanical and electrical capacity Most of single-phase motor capacitor,such acmotor2.blogspot.com as washing machines,electric fans,submersible pump,small woodworking planer,etc.But due to capacitor spoiled or improper selection capacity,Motor running temperature,noise,power consumption increases,the speed is reduced,the phenomenon such as torque decreases,here the selection of electrical and mechanical capacity of the capacitor motor approach to electricity Work friends can do a introduction,for your reference. Calculation method 1:Single-phase capacitor electric mechanical and electrical capacity depends on the size of the deputy winding current.

Because of different sizes,single phase motor power to consider when choosing capacitance rev Dynamic torque,speed,temperature,noise and loss should be within the normal range.So first of all should from the nameplate detect single-phase motor power,calculate the primary winding of the electricity Flow,and then according to the primary winding current (0.5 0.7) times to perkins diesel generator setcalculate the current value of each winding current,according to the formula C = IC * 10 divided by 2 PI fVo.The formula of the I I = P = V is obtained. 2: the selection of capacitor Single-phase capacitor motor should first choose oil-immersed capacitor,pressure value should be above 400 v.Second optional www.facebook.com/guohong.trading ac

electrolytic capacitor,its small size,low prices,but life Life is a bit short.

Three-phase asynchronous motor speed and voltage have a relationship

Simple from the formula,the rotational speed of rotating speed and voltage are theoretically

acmotortrading.blogspot.com has nothing to do,in fact change the applied voltage is affect the speed of the motor.The following description can electric motors 12 volt help understand the asynchronous motor revolutions formula n = 60 f/p * (1-s) p-logarithm,s-slip Speed regulation method 1.Change the frequency of the power supply (2) pole change motor logarithmic 5kw permanent magnet generator 3.Change the slip.Slip changes can be made of the following measures to achieve 1.2.Change the applied voltage in mini electric motor the rotor circuit introduction plus resistance (3) the introduction of additional potential in the rotor circuit.

The difference between the current transformer and voltage transformer

current transformer secondary short circuit,but will not open; Can open circuit voltage transformer secondary,but shall not be short circuit;2) relative to the secondary side of the load,a mini electric motor small internal resistance and voltage transformer can be ignored,can think of the voltage transformer is a voltage source; While current transformer of a resistance is very big,so that can be thought of as a current source internal resistance is infinite.3) voltage transformer normal work of magnetic flux density is close to saturation value,magnetic flux wholesalemotor.blogspot.com density decreased when fault.

Current transformer magnetic flux electric motors 12 volt density is very low in normal working conditions,and short circuit due to the primary side become large short-circuit current,the magnetic flux density increases greatly,sometimes even more than saturated value. Current transformer in electric power

system is an important part of a device,the principle of which is according to the principle of

electromagnetic induction and manufacturing. It's a little coil number of turns,5kw permanent magnet generator usually adopt single-turn coil,namely a copper or a copper platoon. Take mainly secondary coil measuring instrument or relay coil. Current transformer secondary side can not open,when the secondary side open,a side is mainly used for excitation current,this will be induced in the secondary side of high voltage,so as to endanger the safety of the secondary equipment and personal can also cause a current transformer burned.