How to Set up Emergency Stop with Limit Switch and VFD?

In this tutorial, we will guide you step by step through the process of setting up and operating a limit switch for the emergency stop (E-stop) with the VFD GK3000 from ATO. Additionally, we’ll use a motor to demonstrate the functionality of this emergency stop mechanism. All the components discussed in this tutorial, including the VFD and limit switch, are available on ATO.com.

Wiring the Components

To integrate the limit switch with the VFD GK3000, you need to wire it in series with the VFD’s emergency stop input terminal, which is terminal X3. The other side of the limit switch should be connected to the COM terminal, as shown in the circuit diagram provided in the tutorial.

When the limit switch is triggered (engaged), the variable frequency drive will detect the input and immediately stop its output. This triggers a shutdown of the motor, halting its operation for safety.

Parameter Settings Overview

Here are the key parameters you’ll need to set on the VFD to ensure proper operation:

• P0.01 = 1 (Digital frequency setting with power-off memory)
• P0.03 = 0 (Operation via control panel)
• P0.12 = 5 (Acceleration time of 5 seconds)
• P0.13 = 5 (Deceleration time of 5 seconds)
• P3.02 = 47 (Assigning the emergency stop function to input terminal X3)

Make sure to take note of these settings and save them to your device for future reference. These parameters ensure the VFD works as expected in coordination with the limit switch for emergency stop functionality.

Configuring the Parameters

First, power up the VFD and enter the parameter settings by pressing the Menu key. Set P0.01 = 1 to enable digital frequency control with power-off memory, ensuring the VFD retains its last frequency setting even after a power loss. Confirm the setting by pressing Enter, then move on to P0.03 and set it to 0. This will enable operation through the VFD’s control panel, allowing you to control the VFD directly.

Next, configure the acceleration time by setting P0.12 = 5 seconds and the deceleration time by setting P0.13 = 5 seconds. These values control how quickly the motor accelerates and decelerates during normal operation. Once these are set, return to the previous menu level, and navigate to the P3 parameter group and set P3.02 = 47 to assign the emergency stop function to input terminal X3. After confirming the settings, press ESC twice to exit the menu and return to the normal run mode.

Actual Operation and Testing

With the components properly wired and the parameters configured, you can now perform a test run to see the system in action.

Start the VFD: Press the green FWD (forward) button on the VFD control panel to start the induction motor. The VFD should begin outputting power, causing the motor to run and reach the desired frequency (in this case, 50 Hz), which corresponds to the motor’s operating speed.

Trigger the Limit Switch: Physically engage the limit switch by pressing or triggering it manually. Once the limit switch is triggered, the VFD will immediately halt its output.

Observe the Deceleration: After the VFD halts its output, the motor will gradually decelerate over the programmed deceleration time, eventually coming to a complete stop. This is the emergency stop function in action, ensuring the motor safely comes to a halt.

Conclusion

This integration between the industrial limit switch and the VFD GK3000 provides a reliable emergency stop mechanism, adding a layer of safety to your system. In the event of an emergency or critical situation, the limit switch immediately triggers the VFD to stop its output, allowing the motor to decelerate smoothly and safely.

We hope this tutorial has helped you understand the setup and operation of the emergency stop function using a limit switch with the VFD GK3000. If you want to learn more, you can watch the following video.