Three phase network: a power calculation, wiring diagram

Not every people understand that such a circuit. In apartments they are 99% single phase, where the current is delivered to the consumer via one wire and returns on the other (zero). Three-phase network is a system of transmission of electric current flowing in the three wires with the return one. Here the reverse wire is not overloaded due to the shift of the current phase. The electricity produced by a generator driven in rotation by an external drive.

Increasing the load in the circuit leads to increase the strength of the current passing through windings of the generator. In the result, the magnetic field largely resists the rotation of the drive shaft. The number of revolutions begins to decline, and the speed controller gives the command to increase the drive power, for example by feeding a larger amount of fuel to the internal combustion engine. The number of revolutions is recovered, and generated more electricity.

A three-phase system is a 3 circuit EMF of the same frequency and a phase shift of 120°.

Features connect power to private house

Many believe that a three-phase network in the house increases the power consumption. In fact, the limit is set by the electricity supplying organization and is determined by factors:

• The capabilities of the provider;
• Number of consumers
• The line status and equipment.

To prevent power surges and misalignment of the phases should be evenly loaded. Calculation of three-phase system is approximate, because it is impossible to determine which devices are currently connected. The presence of pulsed devices currently leads to increased energy consumption during their start-up.

The power Distribution Board with three phase connection is taken larger than for single-phase power. Possible options for installing a small introductory panel and the other plastic on each phase and on the outbuildings.

Connection to the trunk is implemented via the underground way and air lines. Preference is given last due to its small size, low cost and ease of repair.

Now the air connection is easy to do with the help of self-supporting insulated wire (SIW). The minimum section of aluminum conductors is 16 mm², which are with large stock, enough for a private house.

SIP is mounted on the supports and the wall by means of anchor brackets with clamps. The connection to the main air line and cable entry in the electrical panel is piercing branch clamps. Taken the cable with combustible insulation (VVGng) and is conducted through a metal pipe inserted in the wall.

Air connection, three-phase power-house

When the distance from the nearest support of more than 15 m is necessary to install another pole. This is necessary to reduce loads, leading to a sagging or broken wire.

The height of the point of attachment is 2.75 m and above.

Power distribution Cabinet

Connecting to three-phase network is made on the project, where inside the house is the division of consumers into groups

• Lighting;
• Socket;
• Separate powerful devices.

Some of the load can be disabled for repair while running the other.

Power users is calculated for each group by selecting the required wire cross-section: 1.5 mm² - for lighting, 2.5 mm² - K sockets and up to 4 mm² - to a powerful instrument.

The Wiring is protected against short circuit and overload by circuit breakers.

Electric meter

Regardless of the connection required device energy consumption. 3-phase meter may be connected directly to the network (direct activation) or via a voltage transformer (polyominoes), where the readings are multiplied by a coefficient.

It is Important to observe the connection procedure, where the odd numbers – food, and even – the load. The color of the wires indicated in the description, and the diagram is on the back cover of the device. Input and corresponding output 3-phase meter are indicated by the same color. The most common procedure for accession, when the first phase and the last wire – zero.

3-phase meter direct connection for the home are usually designed to power up to 60 kW.

Before selecting a multirate model should agree with the energy supply company. Modern devices with fixers enable to calculate a fee forelectricity depending on the time of day, to register and record the power values in time.

Temperature performance of the devices are selected as wide as possible. On average, they range from -20 to +50 °C. the Period of operation of the devices is 40 years old with a calibration interval of 5-10 years.

The Counter is connected after the introductory three - or four-pole circuit breaker.

Three-phase load

The consumers are the boilers, motors and other electrical appliances. The advantage of using them is the even distribution of the load on each phase. If three phase network contains unevenly connected to single-phase powerful load, it can lead to imbalance. When electronic devices start to malfunction, and the lights dimly glow.

Wiring Diagram three phase motor to three-phase mains

Working three-phase motors features high performance and efficiency. It does not require the presence of additional launchers. For normal operation it is important to properly connect the device and follow all recommendations.

Wiring Diagram three phase motor to three phase networks creates the rotating magnetic field three windings, connected in star or triangle.

Each method has its advantages and disadvantages. The star schema allows you to smoothly start the engine, but its capacity is reduced to 30 %. This loss is not in the schema of the triangle, but the start-up current load is much greater.

The engine has a box connection where the leads of the windings. If the three of them, the diagram connects only star. In the presence of six findings, the motor can be connected in any way.

Power consumption

For the home owner it is important to know how much energy is consumed. It is easy to calculate all the appliances. Adding all the power, and dividing the result by 1000, to get the total consumption, for example, 10 kW. Appliance a single phase. However, the current consumption increases significantly in a private house, where there is a powerful technique. One device can have 4-5 kW.

It is Important to plan the power consumption of three-phase network at the design stage to ensure symmetry on voltages and currents.

In the house comes the four-core wire on the three phases and neutral. The mains voltage is 380/220 V. Between the phases and the neutral conductor connect the appliance to 220 V. in addition, there may be three-phase load.

Power Calculation three-phase network is in parts. First, it is advisable to calculate the pure three-phase load, e.g. an electric boiler 15 kW induction motor 3 kW. The total power will be P = 15 + 3 = 18 kW. In phase wire when the same current flows I = Px1000/(√3xUxcosϕ). For household electricity cosϕ = 0,95. Substituting in the formula numeric values will get the value of current I = and 28.79 A.

You will Now define a single-phase load. Let the phases they will be P_A = 1.9 kW, P_B = 1.8 kW, P_C = 2.2 kW. Mixed load is determined by summing and is 23.9 kW. The maximum current will be I = of 10.53 And (phase C). Folded it with the current from three-phase load, get the I_C = 39,32 A. the Currents in the remaining phases will be I_B = 37,4 kW, I_A = 37,88 A.

In the calculations of three phase power network, easy to use tables capacity based on connection type.

According to him whether to pick up the appliance and determine the section of the transaction.

Conclusion

With proper design and maintenance of three-phase network is perfect for private homes. It allows you to evenly distribute the load over the phases and connect the additional power of electrical load, permitting the cross section of the transaction.