Polyphase circuits involve multiple alternating current (AC) voltages or currents that are out of phase with each other. These circuits are commonly used in power distribution systems and electric machinery. The names of the phases in a polyphase circuit typically follow a specific convention based on their angular displacement or time relationship. The most common types of polyphase systems are three-phase systems and two-phase systems.
Three-Phase System:
In a three-phase system, there are three AC voltage or current waveforms, each phase being 120 degrees out of phase with the others. The naming convention for the phases is as follows:
Phase A: This is the first phase. It is often called the "A" phase and is typically represented as the reference phase.
Phase B: This is the second phase and is 120 degrees ahead of Phase A. It is often referred to as the "B" phase.
Phase C: This is the third phase and is 240 degrees ahead of Phase A. It is often called the "C" phase.
These phase names are used in industrial and power systems to identify the different phases of the system.
Two-Phase System:
In a two-phase system, there are two AC voltage or current waveforms. The naming convention for the phases can vary based on the specific configuration, but the common naming convention for a "quadrapolar" system is:
Phase 1: Also known as the "A" phase or "R" phase, this is one of the two phases.
Phase 2: Also known as the "B" phase or "S" phase, this is the second phase. It is generally 90 degrees out of phase with Phase 1.
It's worth noting that two-phase systems are less common than three-phase systems and are often used in specialized applications.
In both cases, the naming convention is essential for proper identification and understanding of the phase relationships in the circuit. These conventions help engineers, electricians, and technicians work with the circuits effectively, especially in power distribution, electric motor control, and other applications that involve polyphase systems.