The sequence of inverter commissioning steps - Sunland inverter

Investigation of the function of the inverter system

Before debugging the inverter, it is necessary to carefully read the instruction manual and related information of the inverter to be debugged to understand the use environment and precautions. Especially before the inverter is energized, it is necessary to carefully investigate and check whether the inverter has obvious signs of problems, such as whether its input and output terminals meet the requirements of the manual. Keep an eye out for new content additions.

Inorganic no-load operation and debugging of the inverter

Inorganic (i.e., not connected to the motor) no-load (i.e., the motor without load) operation and debugging of the inverter, the following three steps are the most basic and important debugging operations:

(1) Ground the grounding terminal of the inverter and connect the power input terminal to the power supply through the leakage maintenance switch;

(2) Check whether the factory display of the inverter display window is normal, if it is incorrect, it should be reset, otherwise the supplier is required to return it;

(3) Understand the operation keys of the inverter.

The general inverter has 6 keys, such as run, stop, prog, data/enter, up▲, and down▼, and the boundaries of the operation keys of different inverters are basically the same. In addition, some inverters also have function keys such as monitor/display, reset, jog, shift, etc., which need to be debugged.

The sequence of inverter commissioning steps - Sunland inverter

The sequence of inverter commissioning steps - Sunland inverter

The inverter is debugged with no-load operation

The following four steps are very important for the commissioning of the inverter with the machine (i.e., connected to the motor) and no-load (i.e., the motor without load).

(1) Set the power of the motor, the number of pole pairs, and check the operating current of the inverter.

(2) Set the maximum output frequency and base frequency of the inverter and set the torque characteristics of the motor. The selection of the voltage/frequency (V/F) operation method includes items such as the highest operating frequency, the basic operating frequency (i.e., the base frequency), and the torque type.

The maximum frequency refers to the highest frequency that the inverter motor system can operate, because the maximum operating frequency of the inverter itself may be relatively high, when the maximum operating frequency allowed by the motor is lower than the maximum operating frequency of the inverter, the frequency of the operation should be set according to the requirements of the motor and its load.

The basic operating frequency of the inverter refers to the dividing line between the constant power control and constant torque control of the motor by the inverter, which should be set according to the rated voltage of the motor. Whereas, the torque type refers to whether the load is a constant torque load or a variable torque load.

In the process of device commissioning, the user can select one of the operation modes according to the V/F operation mode diagram and load characteristics in the inverter instruction manual. The general inverter is equipped with a number of V/F curves for users to choose, and the appropriate V/F curve should be selected according to the load nature.

However, in the case of fan and pump loads, the torque operation code of the inverter should be set to the variable torque and reduced torque operation characteristics. In order to improve the low-speed function of the inverter when starting, so that the output torque of the motor can meet the requirements of production load starting, the starting torque should be adjusted. In the frequency conversion speed regulation system of three-phase asynchronous motor, the control of the rotation distance is more complicated. In the low frequency band, because the effects of resistance and leakage reactance cannot be overlooked, if the v/f is still constant, the magnetic flux will be reduced, and thus the output torque of the motor will be reduced. Therefore, in the low frequency band, the voltage should be properly compensated to increase the torque. Generally, the inverter is manually set and compensated by the user.

(3) Set the inverter to the built-in keyboard operation mode, press the stop button and the run button respectively to investigate whether the motor can stop and start normally.

(4) Set the function of the electronic thermal relay in the inverter according to the introduction in the instruction manual of the inverter.

Because the threshold limit of electronic thermal relay is said to be the ratio of the rated current of the motor and the inverter, it is often expressed as a percentage. When the output current of the inverter exceeds its allowable current, the overcurrent maintenance facility will block the output of the inverter.

Therefore, the maximum threshold value of the inverter's electronic thermal relay cannot exceed the maximum allowable output current of the inverter. At the same time, it should be noted that the overload maintenance setting value of the inverter can also be modified.

The sequence of inverter commissioning steps - Sunland inverter

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