Shelly devices are commonly used for switching various electrical loads, including inductive loads. However, when inductive loads are switched through Shelly devices, there is a possibility of unintended reboots occurring. This technical documentation aims to provide guidelines for preventing such reboots by installing RC snubbers on the affected channels.
2.Understanding the Issue:
2.1 Inductive Loads: Inductive loads, such as motors, transformers, fans and solenoids, generate a back electromotive force (EMF) when current through them is interrupted. This back EMF can cause voltage spikes and transients that may negatively affect the Shelly devices, leading to unexpected reboots.
2.2 Unintended Reboots: Unintended reboots occur when the Shelly device's power supply is momentarily disrupted due to the voltage spikes induced by inductive loads. This disruption causes the device to lose power temporarily, leading to a reboot and potential disruption of the intended operation.
3.Solution: RC Snubber Installation: To mitigate the unintended reboots caused by inductive loads, it is crucial to install RC snubbers on each channel where such loads are switched through the Shelly device. An RC snubber is a passive circuit that suppresses voltage spikes and transients, protecting the Shelly device from the adverse effects of inductive loads.
4.RC Snubber Installation Guidelines: Follow the steps below to install RC snubbers effectively and prevent unintentional reboots caused by inductive loads:
4.1 Identify Affected Channels: Identify the specific channels of the Shelly device that control the switching of inductive loads. It is essential to focus on these channels to install the RC snubbers accurately.
4.2 Installation Process: Follow these steps to install the RC snubbers effectively:
Disconnect the power supply to the Shelly device and ensure all connections are safely de-energized.
Identify the terminals or connectors associated with the affected channels.
Cut the wires leading to the terminals/ connectors using wire cutters/strippers, ensuring you have enough wire length to work with.
Connect the RC snubber components (resistor and capacitor) in series or parallel, depending on the circuit design. (MAKE SURE THAT RC SNUBBER IS INSTALLED NEXT TO THE INDUCTIVE LOAD, NOT SHELLY DEVICE)
Solder the connections between the RC snubber and the wires if necessary.
Insulate the connections using heat shrink tubing or electrical tape to prevent accidental contact or short circuits.
Reconnect the modified wires to the terminals/connectors on the Shelly device, ensuring correct polarity and secure connections.
Double-check all the connections and ensure that the RC snubbers are firmly installed.
Restore the power supply to the Shelly device and verify that it functions correctly without any unintended reboots.
Testing and Maintenance: After installing the RC snubbers, it is essential to perform thorough testing to verify the effectiveness of the solution. Additionally, regular maintenance and inspection of the RC snubbers and associated connections are recommended to ensure continued protection against unintended reboot.