Remote dimmering via Powerline
The MP320 hardware makes it possible to control light intensity as well as when to turn lights on/off in different environments.
That is the case of street lighting. The main advantage is that feeder cables already present can be used, also for data communication, and therefore, there is no need to lay new, dedicated cables to control light fixtures.
The dimmer (from the English verb to dim: lower, dim a light) is an electronic regulator used to control the power absorbed by a load (limiting it at will). In Italian it is also known as varialuce.
The control of the power transferred to a load can be based on a rheostat for the regulation of the voltage (which is not very efficient) or the duty cycle of the load can be changed by transferring only part of the voltage sinusoid applied by the electric network (modulation called phase control and sometimes we talk about phasic dimmer).
Another type of control is obtained with the use of a variable autotransformer called variac. The efficiency is good and the disturbances are reduced. Compared to the dimmer has some disadvantages: larger size, difficulty of a remote control and presence of a sliding contact on which is present all the current to be controlled.
The first electronic dimmer was made in 1961 by Joel Spira, founder of Lutron Electronics. Dimmers are used in lighting technology to regulate the light intensity of incandescent or halogen lamps.
There are many types of dimmers from those used in the home for the regulation of a single lamp to those that regulate the light intensity of entire devices such as those present in theaters or other large complexes. The dimmers can be equipped with mechanical or electronic devices that allow their calibration. Since they are very common use, integrated circuits have been made exclusively for this function.
Remote controlled dimmers exist, sometimes regulated through the Digital MultipleX communication protocol (also called DMX). In the most common versions, suitable for the systems of our houses, the command is made by a button, a knob or by simple touch.
Starting from the beginning of the half wave (when the SCR is not active and therefore it is an open circuit) the applied voltage (through the series load with negligible resistance compared to the illustrated control circuit) increases the voltage on the capacitor C by a delay adjustable by the variable resistor R (the zener diode ZD has in this phase a negligible current because its voltage is below the trigger knee). When the voltage on C reaches the value that leads to ZD conduction a current is applied on the gate of the SCR which sends it into conduction (it becomes a short circuit in first approximation, in reality there remains a voltage of about one volt, the main limiting point the efficiency of the circuit). This involves the activation of the load and, through D1, the discharge of C so that the next half-wave is discharged again. The SCR will remain in operation until its current drops to zero at the end of the half-wave. At this point the circuit repeats its cycle at the beginning of the next half-wave.