How to avoid frequency converter from load shock

- Dec 27, 2019-

Shut down, decelerate too fast, very easy to damage frequency converter, so what is the specific reason?

For the instantaneous power failure restart with large inertia load, the starting mode should also be set reasonably. First, the motor should be stopped and then started. When the inverter is in the state of stop, the motor should be set as: speed tracking starting mode.Mechanical braking and any external electrical braking are strictly prohibited in the mechanical equipment using the frequency converter, otherwise the frequency converter will be damaged.

In order to ensure safe operation of the frequency converter and avoid the impact of load on the frequency converter, the following points must be done:

(1) make sure that the frequency converter has sufficient acceleration and deceleration time as far as possible;When shutdown or decelerate, oneself have soft shut off function.Increase the acceleration and deceleration time as much as possible within the range allowed by the equipment.

(2) for the instantaneous power failure restart with large inertia load, the appropriate starting mode should be set, which should be: first braking and then starting; while for the inverter in the state of stop, the motor with positive or reverse small inertia load (such as small fan) should be set as: speed tracking starting mode.

(3) mechanical braking and any external electrical braking are strictly prohibited in the mechanical equipment where the frequency converter is applied, otherwise the frequency converter will be damaged.

(4) are strictly prohibited in the operation, disconnect or connect the output lines, in the operation of the switch must be connected or disconnected (e.g., contactor), must be strictly in accordance with the following steps: first, through the control loop makes the inverter output, make the motor to stop running, and switching inverter output line switch, after waiting for output line switch to connect, to restart inverter, into the normal operation.

(5) the connection between the inverter and the motor shall not be too long, less than 100 meters as far as possible, and the cross-sectional area shall not be too large.Otherwise, the parasitic capacitance of the cable is too large, which increases the ground leakage current, and the power switching device will produce too large peak current at the moment of breaking, which is easy to damage the power inverter module, making the inverter protection action unusable.If the connection is too long, an output reactor can be installed on the output side to compensate.