1. How to connect the power cord of the frequency converter
If you want to figure out how to connect the power cord of the frequency converter, you must first understand what the frequency converter is. A motor speed regulating device that outputs different voltages and frequencies to change the speed of the motor. From this role, it is a variable AC power supply that can receive command-controlled high-power power supplies, and high-power power supplies , are essentially a kind of power transformation technology, and they all need to supply high-power input power, so they need a so-called main loop circuit. So how to connect the power line of the inverter?
1. The power supply should be connected to the input terminals R, S, and T of the inverter, and must not be connected to the output terminals (U, V, W) of the inverter, otherwise the inverter will be damaged.
2. Do not connect anything other than the recommended braking resistor option between terminals + and PR, or absolutely do not short-circuit.
3. Electromagnetic wave interference. The input/output (main circuit) of the frequency converter contains harmonic components, which may interfere with communication equipment near the frequency converter. Therefore, install the optional radio noise filter FR-BIF or FRBSF01 or FR-BLF line noise filter to minimize interference.
4. When wiring over long distances, due to the influence of the charging current of the parasitic capacitance of the wiring, the rapid response current will The limiting function is reduced, and the instrument connected to the secondary side malfunctions and causes a malfunction. Therefore, the maximum wiring length must be less than the specified value. If the wiring length has to be exceeded, please set Pr. 156 is set to 1.
5. Do not install power capacitors, surge suppressors and radio noise filters on the output side of the inverter. Otherwise, it will cause the inverter to malfunction or the capacitor and surge suppressor to be damaged.
6. In order to keep the voltage drop within 2%, appropriate types of wires should be used for wiring. When the wiring distance between the inverter and the motor is long, especially in the case of low-frequency output, the voltage of the main circuit cable will drop, causing the motor’s torque to drop.
7. After operation, changing the wiring must be done after the power is cut off for more than 10 minutes and the voltage is checked with a multimeter. For a period of time after a power outage, dangerous high-voltage electricity remains on the capacitor.
2. What are the precautions for wiring the power cord of the inverter?
1. The wiring principles of different brands and models of inverters are similar, and the wiring of the inverter needs to be strictly followed. Drawings or instructions for wiring.
2. ChangeA high-frequency switching state will occur during the operation of the inverter, and its leakage inductance may induce dangerous voltages on the heat sink or chassis. In order to prevent electric shock, the E terminal of the inverter box needs to be grounded.
3. It is best to connect an air switch to the input end of the frequency converter. The protection current value cannot be too large for short circuit protection.
4. The control line should be as short as possible. If the control line is too long, it will easily cause the control board to malfunction due to electromagnetic wave interference, which will affect the normal operation of the inverter to a certain extent.
5. In order to prevent electromagnetic interference, it is best to use shielded cables for the input lines, output lines, and control lines of the inverter. The shielding layer should be well grounded. If necessary, a filter can be added.
6. The most important thing: the neutral line N must not be grounded! Because when the inverter drives the motor to a braking state, the motor is similar to a generator at this moment, and the electric energy will be “blocked” by the inverter’s internal rectifier module on the main circuit board. Under normal wiring conditions, the inverter will perform protection and voltage reduction, but If the neutral wire N is directly connected to the ground, a loop will be formed and a large current will be generated, exceeding the withstand voltage of the circuit board, and the module will explode.
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