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