CNIf you want to figure out how to wire the inverter, you must first understand what the inverter is. The inverter is a motor speed control device. It will output different voltages and frequencies to change the speed of the motor. From this function, it It is a variable AC power supply, which can receive command-controlled high-power power supply, and the high-power power supply is essentially a kind of power transformation technology, which needs to supply high-power input power supply, so the so-called main circuit circuit is required; What kind of voltage and frequency the power supply should output is controlled by people or other equipment commanded by people, which requires a control loop circuit.
The structure of the frequency converter is to first rectify the power frequency power supply into DC, and then invert it into a variable voltage and frequency power supply to drive the motor. Any frequency converter is the same, as long as it is connected to the main circuit and the control circuit.
Inverter wiring method
1. Wiring of the main circuit
1. The power supply should be connected to the R, S, T terminals of the inverter input terminals, and must not be connected to the inverter output terminals (U, V, W), otherwise the inverter will be damaged. After wiring, the bits and pieces of wires need to be cleaned up, as they may cause abnormalities, malfunctions and failures, and the inverter must always be kept clean. When punching holes on the console, be careful not to let debris and powder enter the inverter;
2. Between terminals + and PR, do not connect anything other than the recommended brake resistor option, or do not short circuit;
3. Electromagnetic wave interference, the input/output (main circuit) of the frequency converter contains harmonic components, which may interfere with the 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 the interference;
4. In the case of long-distance wiring, due to the influence of the charging current of the parasitic capacitance of the wiring, the fast response current limiting function will be reduced, and the instrument connected to the secondary side will malfunction and malfunction. Therefore, the wiring length should be smaller than the specified value. As a last resort, if the wiring length exceeds the limit, 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. Failure to do so will result in failure of the inverter or damage to capacitors and surge suppressors;
6. In order to keep the voltage drop within 2%, wires of appropriate type 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 torque of the motor will drop due to the voltage drop of the main circuit cable.
7. After running, the operation of changing the wiring must be carried out after the power is cut off for more than 10 minutes and the voltage is checked with a multimeter. Dangerous high voltages remain on capacitors for some time after a power outage.
2. Wiring of the control circuit
The control circuit of the frequency converter can be roughly divided into two types: analog and digital.
1. The wiring of the control circuit terminals should use shielded wires or twisted pairs, and must be wired separately from the main circuit and strong current circuit (including 200V relay program circuit);
2. Since the frequency input signal of the control circuit is a small current, in the case of contact input, in order to prevent poor contact, the small signal contact should use two parallel nodes or use twin contacts;
3. The wiring of the control circuit generally uses cables of 0.3 to 0.75 square meters.
3. Ground wiring
1. Due to the leakage current in the frequency converter, in order to prevent electric shock, the frequency converter and the motor must be grounded;
2. Special ground terminal for inverter grounding. To connect the ground wire, use a tin-plated crimp terminal. When tightening the screws, be careful not to damage the turnbuckle;
3. No lead in tin plating;
4. The grounding cable should be as thick as possible, and must be equal to or greater than the specified standard. The grounding point should be as close to the inverter as possible. The shorter the grounding wire, the better.
4. Precautions for inverter wiring.
1. The wiring principles of different brands and models of inverters are similar, and the wiring needs to be strictly in accordance with the wiring drawings or instructions of the inverter;
2. There will be a high-frequency switching state during the operation of the inverter, and its leakage inductance may induce dangerous voltage on the cooling plate or the casing. In order to prevent electric shock, the E terminal of the inverter box needs to be grounded;
3. An air switch should be connected to the input end of the frequency converter as much as possible, and the protection current value should not be too large, and short-circuit protection should be carried out;
4. The control circuit should be as short as possible. If the control circuit is too long, it will easily cause the control board to be interfered by electromagnetic waves and cause malfunction, which will affect the normal operation of the inverter to a certain extent;
5. In order to prevent electromagnetic interference, the input line, output line, and control line of the inverter should use shielded cables as much as possible, and the shielding layer should be grounded well, and filters can also be added if necessary;
6. The neutral line N must not be grounded! ! Because when the motor driven by the frequency converter is in the braking state, the motor is similar to a generator at this moment, and the electric energy will be "blocked" to the main circuit board by the internal rectification module of the frequency converter. Under normal wiring conditions, the frequency converter will perform protection and step-down, but If the neutral line N is directly grounded, a loop will be formed and a large current will be generated, exceeding the withstand voltage of the circuit board, and the module will burst!
