3.3.7 Zero-Crossing Detector Circuit

Phase identification is an important feature of devices that are connected to Smart Grid networks, such as smart meters. A typical implementation is based on measuring the time difference between a specific PLC frame reception and the last zero crossing event of the mains single-phase to which the device is connected.

Important: The phase identification feature is mandatory for G3-PLC and PRIME1.4, but not for PRIME1.3.

Figure 3-15 shows the Zero-Crossing Detection circuit used in the PL360G55CF-EK board, which features detection of rising edges of the mains voltage. The output signal of the detection circuit “VZ CROSS” is connected to VZ pin of PL360 and a synchronization algorithm is applied in order to obtain an accurate measurement of the time between PLC frame reception and zero crossing events.

Figure 3-15. Zero-Crossing Detection Circuit

Notice: Designs that do not require galvanic isolation can use a simpler Zero-Crossing Detector circuit, such as a Zener diode, instead of the previous circuit.