Simple three-phase power grid measurement interface circuit diagram

Three-phase alternating current is a form of transmission of electrical energy, referred to as three-phase power. Three-phase AC power supply is a power supply composed of three AC potentials with the same frequency, equal amplitude, and phase differences of 120° from each other. Three-phase alternating current has many uses. Most AC power equipment in industry, such as motors, use three-phase alternating current, which is the often mentioned three-phase four-wire system. In daily life, single-phase power supply is mostly used, also called lighting power. When lighting electricity is used for power supply, one of the three-phase electricity is used to power electrical equipment, such as household appliances, and the other line is the fourth line of the three-phase four-wire, which is the neutral line. The neutral line is drawn from the neutral point of the three-phase electricity.

The figure below shows a simple three-phase power grid measurement interface circuit, which is mainly composed of 8031, SN74LS74, LM339 and other components.