General converter electrical engineer to teach you the overcurrent

General converter electrical engineer to teach you the overcurrent protection and treatment methods Overcurrent protection function of the frequency converter is a very important role in the frequency converter,the following introduce you to the cause of the over current and processing method Frequency converter in the overcurrent protection object refers to with paroxysmal qualitative,peak current,exceeds the permissible value of frequency converter.As a result of the inverter device overload ability is poor,so frequency converter overcurrent protection is a vital link,so far has been very perfect.(1) the cause of the over current A.over current work The current system appeared in the process of work.The reason for this is roughly from the following aspects: A) motor encounter impact load or drive mechanism to the sudden increase of motor current phenomenon of "stuck".B) inverter output short-circuit,such as the connecting line between the output to the motor motor internal short circuit or short circuit,etc.C) inverter itself is not normal work,such as two of the same bridge arm in inverter bridge inverter device in the process of alternating work abnormal.For example due to environment temperature is too high,or aging,the inverter device itself to change the parameters of the inverter device,cause in the process of alternating,a device has been conducting,and another device but also in the future and shut off,causing the same bridge arm of the upper and lower two parts of "straight",the dc voltage between the positive and negative in the short circuit state.

B.over current acc When the load of the large inertia,and set up time and too short,means in the process of advance,the working efficiency of the converter rise too fast,the synchronous speed of the motor because of the large inertia load and couldn't keep up with,and the result is acc current is too big.induction motor price C.over current slow down When the load of the large inertia,and slow down the time set too short,can also cause overcurrent.Because of the slow down,the time is too short,synchronous speed drops rapidly,due to the load and the motor rotor inertia is big,still maintain a high speed,then the same can be the speed of the rotor winding cutting lines of magnetic force is too big and over current generation.(2).Treatment methods A -.When starting A liter of tripping speed,this is very serious phenomenon over current,major inspection (1).Working machinery have stuck (2).Load side if there is any short circuit,check over the ground by megohmmeter for short motor fan circuit (3).The inverter power module if there is any damage (4).The starting torque of the motor is too small,the drag system turns up B.starting without tripping immediately,and tripping in the operation process,the main check: (1).Set up time is too short,longer acceleration time (2).Deceleration time setting is too short,longer deceleration time (3).Torque compensation (u/f ratio) set too big,cause the low frequency time load current is too large (4).Improper electronic thermal relay setting,current action set is too small,misoperation caused by frequency converter

The analysis of the causes of leakage of transformer oil - seal structure

I plant oil leakage current transformer are mainly concentrated in four period of current transformer installed in the switching station,four period of current transformer is hunan liling cichang the mid - 90 - products,has been running more than eight years.Current transformer porcelain jacket with expander and motor magnet tank adopts hanging flange connection,this structure has to be eliminated,manufacturers are now used for pressure coil flange connection,compared with the hanging type connection,pressure coil flange connection has the advantage that can make the flange surface stress more evenly.

Manufacturers motor run capacitor of technical improvement,also can prove the existence of hanging join some shortcomings. Current transformer primary winding through the upper porcelain set of four terminals,derivation from the scene of the collapse of the transformer terminals can be found electricalmotor1.blogspot.com at a time,a terminal nanjing cichang the production of transformer and porcelain set of seal,the internal and external two flat pad.And a terminal liling,cichang production of transformer seal only outside a plane pad.Sealing structure differences make liling,cichang transformer produced a joint terminal sealing surface oil leakage occurred frequently.But now the liling manufacturer has also made the improvement to this sealing structure,in electrical motor a terminal seal face to add a seam allowance,o-rings seals,how to be in one step.

Motor vibration

Motor through a transmission mechanism is connected to a machine.motor vibration can ac

electric motor result in mechanical vibration.mechanical vibration also can make the motor vibration.motor and mechanical transmission part release to start the motor.if eliminate vibration is a mechanical failure.or is the motor vibration.vibration reasons:the diesel generator motor seat is not firm.mechanical part of the motor and the driven generator rotor and stator shaft are different.the motor rotor imbalance.motor shaft bending.belt wheel spindle eccentricity.squirrel cage several breaks.bearing damage.unbalanced electromagnetic system.www.dongfeng-motor.com electric JiSao chamber.

Permanent magnet synchronous motor in the elevator of the security and reliability of the development and application

Permanent magnet synchronous motor in elevator design,production,development and utilization,are increased highland elevator traction system security and reliability.When traction and braking failure or other failure cause the elevator upward slide line direction,and speed,it has safety protection,meet the technical standards of GB7588-2003 (elevator manufacture and install security specification 9.10 capsules upgoing overspeed protection device requirements.The use of permanent magnet wholesalemotor.blogspot.com synchronous traction motor of elevator,lost in the TV and remove the dot will grow motor armature winding short section (or short after concatenated adjustable resistor),when a speeding (regardless of upward and downward) failure,speed control system detected signals,immediately cut off power supply circuit of controller,and the motor armature winding short answer (or short after series adjustable resistor).

At this point,the stillness of the winding cutting rotating magnetic fields produced by permanent magnet and the induction electromotive force,caused by the armature winding in closed loop current,the current in the magnetic field under the action of torque,attempt to drive the armature low speed permanent magnet generator winding with magnetic rotation; at the same time,the torque is the moment of the effect on the rotor magnetic pole,trying to make the rotor end with the armature winding of the stator,is a braking torque.The process is similar to dc motor braking energy,against falling so as to realize the speed (brake torque can be adjusted through the resistor the slide speed controllable).

Interaction between permanent magnet and closure of the armature winding,this generates parking autistic non-contact two-way protection,greatly increase the safety and reliability of the elevator,especially reduced all kinds of high-speed elevator safety clamp cheese block caused by high temperature damage in high speed motion security risks.generator stator Because the gearless traction machine of coaxial traction wheel and motor,traction wheel and brake wheel parts,usually as a result,by

adopting the technology of gearless permanent magnet synchronous motor,don't set up overspeed

protection system,in the elevator in the acceptance inspection,of course,also can make the request.In

addition,the synchronous motor can be done by the armature winding for dc load zero speed parking,in order to be truly need not brake of mechanical braking,parking realizes the electrical zero speed.Can help to prevent slide due to brake failure of failure,to three phase induction motor further improve the reliability of the system.