The control of the frequency converter is only the basic logic of starting, stopping, forward rotation, reverse rotation and speed regulation. These logics basically require the level state to be valid, not the rising edge, so the push button switch is used to control the frequency conversion. When using the device, it is usually necessary to use a self-protection push button switch to complete it. If it is not self-protection, an additional intermediate relay is required for self-protection.

Economical frequency converter: 1. Single switch start and stop

The frequency converter can only be started to a high level through the RUN terminal. When the switch is closed, it is equivalent to the RUN terminal becoming a low level, and the frequency converter stops running.

In this case, a self-protection push button switch can be used to meet the start and stop control of the frequency converter. An additional switch can be used for fault reset. When a fault occurs, press the reset switch to clear the frequency converter fault. Since there is no separate potentiometer setting, the frequency can be set through the operation panel at this time.

Of course, the above logic can also be completed by a logic controller such as a PLC.

Economical frequency converter: 2. Double switch to achieve forward and reverse start and stop

In some cases, the forward and reverse rotation of the frequency converter must be controlled. Although the AC asynchronous motor can reverse any two-phase line at the output end of the inverter, the operation is troublesome and laborious, and the inverter starts directly through the reverse rotation. Control function.

For example, if a switch is connected to the forward rotation terminal of the inverter (some are FWD, here is DI1), the inverter will rotate forward at this time. Of course, the switch must be a maintenance type. When the switch is disconnected, the inverter will stop directly.

Similarly, when another switch is connected to the reverse terminal of the inverter (some are REV, here is DI2), the inverter will still run, and the switch must also be maintained. After the switch is disconnected, the inverter will stop running.

If there is no external potentiometer, the frequency value of the inverter can also be given through the panel.

Economical frequency converter: 3. Switch controls start and stop

Another controls speed setting

As mentioned above, one switch controls the start and stop of the frequency converter. The other switch can actually be used to set the speed. A simple one, such as jog control. Some frequency converters, especially those in Europe, can be used internally. Through the parameter setting multi-function terminal, the switch can be set to jog mode, so that the frequency converter can be controlled to work in the jog state through the switch. In the jog state, the frequency converter usually runs at 5%. Of course, this value is also acceptable. Modify separately through the panel.

You can also use the multi-speed function port or UP/DOWN to set it, and its essence is the same as the jog mode. No matter which method is used to control the frequency converter through the switch, its essence is to provide a certain high and low level to the I/O port of the frequency converter. If the frequency converter does not work, you only need to measure the corresponding I/O port with a multimeter to determine whether the signal level is normal, and you can know whether the line connection is correct.