Analysis of overcurrent fault of variable frequenc

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Overcurrent fault analysis of variable frequency drive of 2640mm paper machine

key words: inverter; Overcurrent; encoder; Parameter

our factory installed a 2640mm paper machine manufactured by Xi'an weimeide company in July, 1998, with a design speed of 500m/min. The paper machine adopts SIMOVERT VC vector controlled inverter of Siemens, which has high dynamic quality, high speed accuracy, various function protection, display parameters, fault self diagnosis function, etc. The hardware options of the inverter are PMU parameter setting unit, mainboard Cu2, communication board CB1, operation panel Op25, and communication interface connecting PLC interface. On August 20th, 1999, the upper groove roller of the transmission system was driven by LA5 motor with rated power of 110KW and rated current of 98a. During operation, the inverter showed f011 overcurrent fault

1 schematic diagram and fault analysis of upper grooving roll

1.1 schematic diagram of upper grooving roll inverter (see Figure 1) 1.2 overcurrent fault analysis

since the fault is confirmed, the start-up fails again, so it may be a hard fault. The fault message f011 is an overcurrent fault, that is, the device is shut down due to overcurrent. Electrical personnel shall check whether the inverter output is short circuited and whether there is grounding fault; Whether the working motor is overloaded; Whether the coupling connecting the motor is abnormal; Whether the motor is correctly matched with the inverter, etc. Check the above items and there is no abnormal phenomenon. Use r 005 to check that the output power of the motor is 24%, and use r 004 to check that the running current of the motor is 70A. From the above parameter analysis, the mechanical fault is eliminated, which may be electrical fault. It is found from the electrician's duty record that f053 fault occurred many times in the past few days. F053 represents that the allowable change value of speed signal generator P215 has exceeded, and the original P215 has been changed from 3 to 11. From the above situation, it is considered that the cause of overcurrent fault may be related to encoder feedback. Switch on, confirm according to the fault, use r 214 to check the actual speed value of the motor operation, and the start-up starts from 0.000hz to 69.000hz. After a few minutes, it shows that this is the completion of another milestone node since the air separation start-up and system replacement of hong4 phase 2 project on August 18. 0.000hz, tripping, indicating the internal fault of the encoder, causing overcurrent and tripping. After shutdown, remove the encoder

Figure 1 Schematic diagram of upper grooving roller inverter

(1) dc510v (2) AC220V (3) DC24V (4) L2 bus (5) RS485 bus (6) RS485 (13) motor temperature monitoring (15) encoder (16) shielded wire

2 fault handling measures

after closing, confirm according to the fault, and the upper grooving roller is in the displayed parameter state "009", The original speed closed-loop control is changed to open-loop frequency control. The following process:

p052=5 select the function "system configuration"

p051=3 access level "expert mode"

p163=3 open loop control

p208=0 no encoder

p052=0 return to

after pressing the p key, the operating parameters display 009, representing the "ready to start" state. Restart the upper grooving roll, but the requirement in ISO 8295 (GB 10006 equivalent to ISO 8295) is 100mm/min, which is normal

open the removed encoder and find that there are 5 internal connecting wires inside, including 1 bare skin. Wrap it with insulating tape, then connect the tachometer with + 15V power supply, connect the ammeter in series, and the reading is 45mA. Rotate the shaft, and effectively inhibit the growth of mold with ten thousand mold proof grade 0 (the highest level). The DC gear A and B channels of the meter have voltage output, and the amplitude is 15V, indicating that the encoder has been repaired

stop the machine, replace the repaired encoder, and change p163 from 3 to 4 and p208 from 0 to 1 according to the above method. Start the machine and it is normal

later, the glue application roller and the second drying cylinder all had the same fault, and it was normal to deal with it according to the above methods

3 conclusion

3.1 f011 overcurrent fault check whether the inverter output has short circuit and grounding fault; Whether the working machine is overloaded; Check whether the encoder works normally

3.2 use the R 214 parameter to directly diagnose the encoder

3.3 it is convenient and rapid to modify parameters by using system parameter p052

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