Open box Shelly Pro 3EM Switch Add-On

What does "open box" mean?

Open-box products are returned products with opened or damaged packaging, but fully checked from a technical point of view and completely functional. They come with the same warranty as new products.

The Shelly Pro 3EM Switch Add-on is a galvanically isolated expansion module designed specifically to complement the functions of the Shelly Pro 3EM energy meter. By connecting to the proprietary Shelly bus, the add-on adds a controllable dry contact, useful for controlling contactors or other electrical equipment based on the measured consumption data.

Being galvanically isolated, the module can safely control loads separate from the measuring circuit, without the risk of electrical interference between the monitoring side and the switching side. It mounts on a DIN rail, directly next to the Shelly Pro 3EM, and is powered by it.

It is frequently used in energy management applications, such as automatically disconnecting a contactor when consumption exceeds a set threshold, starting a pump or auxiliary equipment depending on the output of a photovoltaic system, or integration into load-shedding scenarios for commercial buildings.

Note: The Shelly Pro 3EM Switch Add-on does not work on its own and requires an installed Shelly Pro 3EM meter, to which it connects physically via the Shelly bus on the DIN rail.

Practical use cases

• Automatically disconnects a contactor when the consumption measured by Shelly Pro 3EM exceeds the set threshold, to avoid overloading the mains connection.
• Switches on a pump or auxiliary equipment when the photovoltaic system produces enough energy, based on the data measured by Pro 3EM.
• Used in load-shedding scenarios in commercial buildings, to disconnect non-essential loads during peak periods.
• Safely controls a load separate from the measuring circuit, thanks to the galvanic isolation between the monitoring side and the switching side.

Technical specifications

For installations where the Shelly Pro 3EM already monitors three-phase consumption, the switching add-on turns the measured data into direct automatic actions on contactors or auxiliary equipment.