The signal line and the power line must be separated. When using the analog signal for remote control of the inverter, in order to reduce the interference of the analog quantity from the inverter and other equipment, please control the signal line and the strong circuit of the inverter (main circuit). And the sequence loop) separate the lines. The distance should be more than 30cm. Even in the control cabinet, it is necessary to maintain such wiring specifications. The control loop between this signal and the frequency converter must not exceed 50m. Suizhou simi intelligent technology development co., LTD , https://www.msmsmart.com
The signal line and the power line must be placed inside different metal pipes or metal hoses separately: if the signal line connecting the plc and the inverter is not placed in the metal pipe, it is highly susceptible to interference from the inverter and external equipment; There is no built-in reactor, so the input and output stage power lines of the inverter will have strong interference to the outside. Therefore, the metal tube or metal hose for placing the signal line should be extended to the control terminal of the inverter to ensure the signal line. Completely separated from the power line.
1) The analog control signal line should use double stranded shielded wire with a wire size of 0.75mm2. When wiring, be sure to note that the cable stripping should be as short as possible (5-7mm), and the shield after stripping should be wrapped with insulating tape to prevent the shield from coming into contact with other equipment to introduce interference.
2) In order to improve the simplicity and reliability of the wiring, it is recommended to use the crimping bar terminal on the signal line.
The operation of the inverter and the setting of related parameters:
There are many setting parameters of the inverter, and each parameter has a certain range of selection. In use, it is often encountered that the inverter cannot work normally due to improper setting of individual parameters.
Control mode: speed control, torque control, PID control or other means. After taking the control method, it is generally necessary to perform static or dynamic identification according to the control accuracy.
The lowest operating frequency: that is, the minimum running speed of the motor. When the motor runs at low speed, its heat dissipation performance is very poor. When the motor runs at low speed for a long time, the motor will burn out. At low speeds, the current in the cable also increases, which can also cause the cable to heat up.
The highest operating frequency: the general frequency of the inverter reaches 60Hz, and some even reach 400Hz. The high frequency will make the motor run at high speed. For ordinary motors, the bearings can't run for a long time at super rated speed. Can the rotor of the motor be able to run? Withstand such centrifugal force.
Carrier frequency: The higher the carrier frequency setting, the higher the higher harmonic component, which is closely related to the length of the cable, the heating of the motor, and the heating of the cable heating inverter.
Motor parameters: The inverter sets the power, current, voltage, speed and maximum frequency of the motor in the parameters. These parameters can be directly obtained from the motor nameplate.
Frequency hopping: At a certain frequency point, resonance may occur, especially when the whole device is relatively high; when controlling the compressor, avoid the surge point of the compressor.
Common fault analysis:
1) Overcurrent fault: Overcurrent fault can be divided into acceleration, deceleration, and constant speed overcurrent. It may be caused by the acceleration/deceleration time of the inverter being too short, the load is abrupt, the load is not evenly distributed, and the output is short-circuited. At this time, it is generally possible to extend the acceleration/deceleration time, reduce the sudden change of the load, apply the energy-consuming braking element, carry out the load distribution design, and inspect the line. If the load inverter is disconnected or the overcurrent fault occurs, the inverter inverter circuit has been looped and the inverter needs to be replaced.
2) Overload fault: Overload fault includes inverter overload and motor overload. It may be caused by the acceleration time being too short, the grid voltage being too low, and the load being too heavy. Generally, the acceleration time can be extended, the braking time can be extended, the grid voltage can be checked, and the like. If the load is too heavy, the selected motor and inverter cannot be dragged by the load, or it may be caused by poor mechanical lubrication. If the former, the high-power motor and inverter must be replaced; if the latter, the production machinery should be inspected.
3) Undervoltage: It indicates that there is a problem with the input part of the inverter power supply, and it needs to be checked before it can run.