1. Signal lines and power lines must be separated: when using analogue signals for remote control of the frequency converter, in order to reduce the interference of the analogue from the frequency converter and other equipment, please separate the signal lines controlling the frequency converter from the strong power circuit (main circuit and down-control circuit). The distance should be at least 30 cm. Even inside the control cabinet, it is important to maintain this wiring specification. The maximum length of the control loop between this signal and the frequency converter must not exceed 50m.
2. The signal line and the power line must be placed separately inside separate metal pipes or metal hoses: the signal line connecting the PLC and the inverter is extremely susceptible to interference from the inverter and external equipment if it is not placed inside a metal pipe; at the same time, as the inverter has no built-in reactor, the input and output level power lines of the inverter will produce extremely strong interference to the outside, so the metal pipe or metal hose where the signal line is placed The metal tube or metal hose for placing the signal lines should always be extended to the control terminals of the inverter to ensure that the signal lines are completely separated from the power lines.
1) The analogue control signal line should be a double stranded shielded wire of 0.75 mm2. When wiring, care must be taken to keep the cable stripping as short as possible (about 5-7 mm) and to wrap the shielding layer after stripping with insulating tape to prevent interference from being introduced by the shielding line in contact with other equipment.
2) In order to improve the simplicity and reliability of the wiring, it is recommended to use crimp bar terminals on the signal lines.
3) Operation of the frequency converter and setting of relevant parameters: The frequency converter has many setting parameters, each of which has a certain selection range.
3. Control mode: i.e. speed control, pitch control, PID control or other modes. After taking the control mode, generally according to the control accuracy, need to carry out static or dynamic identification.
4. Minimum operating frequency: that is, the minimum speed of motor operation, the motor running at low speed, its heat dissipation performance is very poor, the motor running at low speed for a long time, will lead to motor burn. Also at low speed, the current in its cable will increase, which will also cause the cable to heat up.
5. Maximum operating frequency: general frequency converter maximum frequency to 60 Hz, some even to 400 Hz, high frequency will make the motor high-speed operation, which for ordinary motors, its bearings can not be long over the fixed speed operation, to consider whether the rotor can withstand such centrifugal force.
6. Carrier frequency: the higher the carrier frequency setting, the greater the high harmonic component, which is closely related to the length of the cable, the motor heat, cable heat inverter heat and other factors.
7. Motor parameters: the inverter sets the power, current, voltage, speed and maximum frequency of the motor in the parameters, which can be obtained directly from the motor nameplate.
8. Frequency hopping: at a certain frequency point, there is a possibility of resonance, especially when the whole installation is relatively high; when controlling the compressor, it is important to avoid the wheezing point of the compressor.