Installation and use of VFD (Variable-frequency Drive)

1. Installation of VFD (Variable-frequency Drive) 1. Installation environment of VFD (Variable-frequency Drive) (1) Ambient temperature -10℃～40℃ (2) Relative humidity of the environment should not exceed 90 (no condensation) ( 3) Other conditions No direct sunlight, no corrosive gas and flammable gas, less dust, and the altitude is lower than 1000m Satisfy the following conditions: Both sides ≥ 100mm Up and down ≥ 150mm (2) The installation of a single VFD (Variable-frequency Drive) in a cabinet should adopt the cooling method outside the cabinet as much as possible (when the environment is relatively clean and less dust); a single VFD (Variable-frequency Drive) Drive) when cooling in the cabinet is used, an exhaust cooling fan should be installed on the top of the cabinet, and it should be installed directly above the VFD (Variable-frequency Drive) as much as possible; Multiple VFDs (Variable-frequency Drive) should be installed side by side as much as possible, such as It must be installed vertically, and a partition should be installed between two VFDs (Variable-frequency Drive). Either way, the VFD (Variable-frequency Drive) should be installed vertically. 2. VFD (Variable-frequency Drive) wiring 1. Main circuit wiring (1) VFD (Variable-frequency Drive) input (R, S, T) output (U, V, W) must not be connected wrongly (2) Main Selection of circuit wire diameter ① The wiring between the power supply and VFD (Variable-frequency Drive) is the same as the wire diameter selection method of the motor with the same capacity ② The connection between the VFD (Variable-frequency Drive) and the motor should consider the line voltage drop △U. General requirements: △ U≤(2～3)Un In the formula: Imn-motor rated current (A) R0-unit length (per meter) wire resistance (mΩ/m), you can check the table below L-wire length (m) Nominal Cross-sectional area / 1.0 1.5 2.5 4.0 6.0 10.0 16.0 25.0 35.0 / (mΩ/m) 17.8 11.9 6.92 4.40 2.92 1.73 1.10 0.69 0.49 (1) Analog control line Shielded wires should be used, and one end of the shield should be connected to the common terminal (COM) of the VFD (Variable-frequency Drive) control circuit, and not connected to the VFD (Variable-frequency Drive) ground terminal (E) or the ground, and the other end should be suspended. (2) It is not allowed to use shielded wires for switch control wires, but two wires of the same signal must be twisted together. 3. Grounding of VFD (Variable-frequency Drive) If multiple VFDs (Variable-frequency Drive) are grounded, each VFD (Variable-frequency Drive) should be connected to the ground respectively. It is not allowed to ground one VFD (Variable-frequency Drive) and Connect the ground terminal of another VFD (Variable-frequency Drive) to ground. 3. Improve the power factor of VFD (Variable-frequency Drive) Add DC reactor and AC reactor. In addition to improving the power factor, it also has the following functions: (1) Suppressing the surge current in the input (2) Weakening the influence caused by the unbalanced power supply voltage Selection of reactance: (1) The voltage drop of the reactor is not greater than the rated voltage 3. (2) When the transformer capacity is greater than 500KVA or the transformer capacity exceeds the VFD (Variable-frequency Drive) capacity by more than 10 times, a reactor should be equipped. 4. Anti-jamming of VFD (Variable-frequency Drive) 1. External interference to VFD (Variable-frequency Drive) mainly comes from the incoming power line. When the power system is put into other devices (such as capacitors) or due to the operation of other devices (such as thyristors and other commutation devices), it is easy to cause distortion of the power supply and damage the switching tube of the VFD (Variable-frequency Drive). Connecting an AC reactor in series with the VFD (Variable-frequency Drive) input circuit can effectively suppress the interference from the incoming line. 2. Interference of VFD (Variable-frequency Drive) to the outside world (1) Propagation method of interference signal Air radiation method uses electromagnetic wave to radiate to the outside. Propagation through the line source network (2) Anti-interference measures ① Interference signals propagated by VFD (Variable-frequency Drive) side induction, through correct wiring and use of shielded wires to weaken the interference signals propagated by the line, can be serialized in the line A small inductance is used to weaken the interference signal transmitted by radiation, and it is weakened by absorption (radio anti-interference filter). A filter reactor is connected in series between the output side of the VFD (Variable-frequency Drive) and the motor, which can not only play a role in anti-interference It can also weaken the additional torque caused by high-order harmonics and improve the operating characteristics of the motor. On the output side of VFD (Variable-frequency Drive), it is absolutely not allowed to use capacitors to absorb harmonic current. ② Instrument side power isolation method The instrument power side is connected to the isolation transformer signal isolation method The signal side is isolated with a photocoupler 5. Measurement of VFD (Variable-frequency Drive) 1. Input voltage at the input side Electromagnetic instruments are suitable, and thermoelectric instruments can also use input power. Electric instruments can be used. It should be noted that power factor meters must not be used to measure power factor on the VFD (Variable-frequency Drive) input side. 2. Output side Output voltage If you use a rectifier meter, if you use an electromagnetic meter, you will measure the fundamental voltage value, which is relatively low. Absolutely no digital instruments. It is advisable to choose an electromagnetic meter for the output current, and the thermoelectric meter can also use an electric meter for the output power. 3. Measurement of insulation resistance All connections are disconnected. To measure the insulation resistance of the VFD (Variable-frequency Drive) main circuit, the input and output terminals of the VFD (Variable-frequency Drive) must be connected together (R, S, T, U, V, W are connected into a line).