How to judge the ABc term of three phase electricity, and how to judge the A, B and C phases of thre

Representing the phases of ABC, the rule B lags 120 degrees compared with phase A in the three-phase system, and C lags 120 degrees compared with phase B, so there is a problem of phase order. The three phases a, b, and c are indicated by yellow, green, and red, respectively. There is a phase difference between different phases.

There is also a voltage difference, which cannot be connected together, if the local area such as office buildings introduces three-phase electricity.

However, it is mainly a single-phase electrical appliance in the local area, so you must pay attention to it, do not connect the two fronts casually, and make sure that the same phase is on the line. As for the issue of phase sequence, it depends on the detailed electrical appliances, if it is an electric heating equipment, it is useless, if it is a motor, it is not, and the direction of rotation of the motor is reversed if the phase sequence is wrong.

The phase sequence of ABC, BCA, CAB is the same, while the phase sequence of CBA, ACB, BAC is the opposite of the previous three. The phase sequence can be measured by a phase sequencer, that is, one is assumed to be phase a, and then B and C are determined.

How to determine the a, b, and c phases of three-phase alternating current?

Three-phase alternating current is a form of electricity that we often use in our daily life, and it consists of three phases of voltage, namely the a, b, and c phases. When installing appliances or wiring, it is important to correctly label the a, b, and c of the power supply as opposed to ensuring the proper functioning of the electrical equipment. So, how to determine the a, b, and c phases of three-phase alternating current?

Here are a few ways to do this. 1.The tool method uses a professional power tool or test pen to determine the a, b, and c phases of a three-phase power supply.

Place a power tool or test pen in turn on any two wires of the three-phase power supply and observe whether the tool is operating properly (or if the test pen is on). If the tool is functioning properly, then the wire is phase A. Next, touch the retarding tool to the other two wires and observe again if the tool is functioning properly.

If it is in normal operation, then the wire is phase B. Finally, touch the tool to the last two wires, which are phase C if the tool is functioning properly. 2.

The voltage method uses a digital multimeter or test pen to measure the voltage of the disturbance between three-phase power supplies. First, place a multimeter or test pen between any two wires in the power supply and record the voltage value. Next, move the test pen between the other two wires and record the voltage value.

Finally, move the test pen between the last two combing wires to measure the voltage value. Generally speaking, the wire with the largest voltage value is phase A, followed by phase B, and the smallest is phase C. 3.

Color methodIn China, the cables of commonly used three-phase power supplies are color-marked. Among them, the red wire represents phase A, the yellow wire represents phase B, and the blue wire represents phase C. If you can correctly identify the color of the end wires and connect them correctly to the motor or appliance, then you can easily distinguish the a, b, and c phases of a three-phase power supply.

In short, it is very important to correctly identify A, B, and C of three-phase alternating current relative to our daily life and work. The above methods are just a few of them, and you can choose the appropriate method according to your actual needs.

ABC three-phase electricity refers to three alternating current wires that are 120 degrees apart in phase. There are several ways to distinguish ABC three-phase electricity:

1.Observe the color of the cable: usually, the cable of the phase electricity before the three springs will use different colors of insulating holsters according to the different phases, and the commonly used colors in China are red (R), yellow (Y) and blue (B) bright forests, where red represents phase A, yellow represents phase B, and blue represents phase C.

2.Voltage measurement with a multimeter: A digital multimeter can be used to measure the voltage of a three-phase electricity, and the instrument should be placed in AC voltage measurement mode.

Start by placing the two probes on different phase wires, and if the displayed voltage value is the voltage value labeled "Phase Voltage", this value should be recorded as a UAB. Then, place the probe between the first and third wires, and similarly obtain the voltage value, denoted as UAC. Finally, place the probe between the second and third wires, and record the resulting voltage, which is called UBC.

If the three values are UAB, UAC, and UBC, it means that this is ABC three-phase electricity.

3.Distinguish by markings or labels: Near the wires of a cable or appliance, there may be markings or labels on the wires to help identify where the buyer or user should connect the wires.

Three ways to judge:

The first method: look at the color of the line; The colors of A, B, and C of three-phase alternating current are yellow, green, and red, respectively.

The second method: look at the location; The order of the three-phase A, B, and C is arranged horizontally from left to right, from back to front, and the top and bottom are arranged upper, middle and lower.

The third method: use the phase sequence table to detect, this is the ash often drop simple, the three clips are clamped on the three live wires, and you can know it at a glance at the indicator light.

A combination of three symmetrical sinusoidal alternating currents with a phase difference of 120° to each other. It is generated by three sets of symmetrical windings of a three-phase generator, and each winding together with its external circuit is called a phase, which is denoted as a, b, and c respectively. Their combination is called three-phase system, and they are often supplied with three-phase three-wire system and three-phase four-wire system, that is, triangular connection and star connection.

The main advantages of the three-phase system are: saving wires in power transmission; It can generate a rotating magnetic field, and creates conditions for the development and application of asynchronous motors with simple structure and convenient use. The three-phase system does not exclude the supply of power to single-phase loads.

Therefore, three-phase alternating current has gained the most widespread application.

The arrangement of the phase wires of the three-phase alternating current power supply system is in phase order, and the voltage lag is 120 degrees; Because it is a three-phase system, each phase is represented by A, B, and C respectively, which has the difference between phase A, phase B, and phase C. In this power supply system there is also a neutral wire, which is denoted by O. The current power supply system below 10kV in our country adopts the above power supply form, that is, the three-phase four-wire system, which is used in industry, agriculture, mining, etc.

The voltage of each phase to the neutral is 220V. [For example, A is relative to the neutral wire O] and the voltage between the phase wires is 380V [if A is relative to the voltage of phase C] In the actual power supply, the neutral wire O is often connected with the earth [grounding electrode], and the neutral wire at this time is also called the neutral line, which is represented by N. In addition to maintaining the function of forming a loop with the phase wire, it also has the function of leakage protection for the equipment, which effectively prevents the personal electric shock caused by the leakage of the equipment, which is the so-called TN-C system.

In general, phase A is yellow; phase b is green; Phase C is red.

Phase A, phase B, and phase C in the power line are actually artificially defined, and the difference in phasor is 120 degrees from each other. In the case where it is necessary to distinguish between ABC three-phase, there are generally several methods:

In the power system, the phase of the incoming call is calibrated, that is, to tell you which line is A, which line is B, which line is C, according to the phase color mark: phase A is yellow; phase b is green; Phase C is red. Or directly indicate the ABC phase.

When two systems of the same voltage level and the same frequency, but from different power sources are in parallel, the equipotential method is used: the potential difference between the two power supplies is measured, and the A phase of the two power supplies is connected to the two power supplies at both ends of the voltmeter (or voltage transformer), and the voltage of the two B and C phases is measured, if the three voltages are zero, it means that the phase sequence of A, B and C of the two power supplies is the same. It can be run in parallel.

On the user side, it is not necessary to calibrate the ABC phase when using electrical appliances, because there are no requirements for phase sequences for other electrical appliances except for motors, which are affected by the direction of rotation due to phase sequence.

There are three ways to judge:

The first pot: look at the line color; The colors of A, B, and C of three-phase alternating current are yellow, green, and red, respectively.

The second pot: look at the location; The order of the three-phase A, B, and C is arranged horizontally from left to right, from back to front, and the top and bottom are arranged upper, middle and lower.

The third pot method: use the phase sequence table to detect, this is the ash often drop simple, the three clips are clamped on the three live wires, and you will know how simple it is when you look at the indicator light, right?

The a, b, and c phases of three-phase alternating current are arbitrarily determined, and if the motor used is not turned correctly, the two wires can be swapped arbitrarily.

The voltage of the three live wires of three-phase electricity is the same, but the instantaneous voltage is different.

Three-phase AC power supply is a power supply composed of three alternating currents with the same frequency, equal amplitude, and 120° difference in phase.