The operation of any electronic device requires a power supply. A common option for powering many devices in the house - DC power supplies.
DC power supplies are classified according to the following criteria:
● by the principle of operation: transformer and switch-mode;● by output voltage: depending on the nominal supply voltage of the connected consumer (3.3 V, 5V, 12V, 24V, 48V and others);● by output current: depending on the power consumption of the connected consumer;● by type of stabilization: stabilized and unstabilized;● by types of protection: may contain functions of protection against short circuits at the output, protection against overheating, protection against overload, protection against interference in the network;● by design: built-in - are part of the circuit of a particular electronic device, and external - a device in a separate case. Most often, external power supplies are metal and plastic (with the possibility of mounting on a DIN-rail) 

The i3 Engineering Smart Home system also requires the use of power supplies. In addition to sensors, primary transducers and actuators, a DC power supply is also required by the controller.
Atom series controllers are designed to connect power from 9V to 48V. Such a fairly wide range of supply voltage is convenient primarily by the ability to connect to the controller different values of the output voltage of power supplies (with voltages of 12V, 24V, 36V and 48V). Meanwhile, it should be noted that the best option for powering Atom series controllers will be a power supply with 24V DC output.
Much of the sensors, analogue converters, servos, provides for power this is the voltage value. Adjustable air damper drives and analogue pressure sensors in the ventilation system, blinds and curtains drives, adjustable thermal heads of radiators - all these are examples of components of the Smart Home system that are powered mainly by 24V. Another example of using this voltage value in a Smart Home system is powering LED strips.

Compared to power supplies with an output voltage of 12V, 24V units have a number of advantages:
● twice less current consumption, and hence the possibility of laying cables of smaller cross-section, as well as much lower heat loss;● twice as much power can be connected to the output with dimming capabilities of the Atom controller to control the LED strip (because this output is limited by the load current, not the power as a whole)

Choosing the power supply

When installing the power supply should take into account the tendency of its elements to heat. In the vast majority of modern power supplies there is protection against overheating: when overheated, the voltage at the output of the power supply drops to zero, and is restored only after overheating.