21 problems that should be noted when using the inverter (I)

Inappropriate use of the inverter, not only can not play its excellent functions, but also may damage the inverter and its equipment, or cause interference, so the following matters should be noted during the use:

1. The inverter must be selected correctly.

2. Read the product manual carefully and wire, install and use it according to the requirements of the manual.

3. The inverter device should be grounded reliably, and the RF interference should be suppressed to prevent the inverter from causing electric shock due to leakage.

4. When the inverter is used to control the motor speed, the temperature rise and noise of the motor will be higher than when using the grid (power frequency); when running at low speed, due to the low speed of the motor blades, attention should be paid to ventilation cooling and proper load reduction. The motor temperature rise exceeds the allowable value.

5. The impedance of the power supply line should not be too small. The inverter is connected to the voltage grid. When the capacity of the distribution transformer is greater than 500KVA or the capacity of the distribution transformer is greater than 10 times the capacity of the inverter, or when the inverter is connected close to the distribution transformer, due to the loop impedance Small, the input moment will cause a large surge to the inverter, which will damage the rectifier components of the inverter. When the line impedance is too small, an AC reactor should be installed between the grid and the inverter.

6. When the three-phase voltage unbalance rate of the power grid is greater than 3%, the peak value of the input current of the inverter is very large, which will cause the inverter and the connection to overheat or damage the electronic components. At this time, an AC reactor is also required. Especially when the transformer is V-shaped, it is more serious. In addition to installing a reactor on the AC side, it is necessary to install a DC reactor on the DC side.

7. It is not possible to install an oversized capacitor on the incoming side because of increasing the power factor. It is also impossible to install a capacitor between the motor and the inverter. Otherwise, the line impedance will drop and overcurrent will be generated to damage the inverter.

8. The output side of the inverter cannot be shunted in parallel. It is also not possible to parallel capacitors in order to reduce the higher harmonics of the inverter output voltage. Otherwise, the inverter may be damaged to reduce harmonics. A reactor can be connected in series.

9. Starting and stopping the motor with inverter speed regulation, can not directly operate with circuit breaker and contactor, and use the control terminal of the inverter to operate, otherwise the inverter will run out of control and may cause serious consequences.

10. It is generally not advisable to install an AC contactor between the inverter and the motor to avoid overvoltage caused by the interruption and damage the inverter. If it needs to be installed, the output contactor should be closed before the inverter runs.