15 kW 3 phase how many amperes machine

Long gone are the days of ceramic plugs that were screwed into home electrical panels. Currently, various types of circuit breakers that perform protective functions are widely used. These devices are very effective against short circuits and overloads. Many consumers have not yet fully mastered these devices, so the question often arises which machine should be installed at 15 kW. The reliable and durable operation of electrical networks completely depends on the choice of machine.

Which machine is suitable for 15 kW

The purpose of a 3-phase machine is protection against overcurrents and overloads. The 15 kW modification operates on a network with a voltage of 380 V, that is, you will need a 25 A device for input. When choosing, you need to take into account that in conditions of short circuits, the current strength increases and can cause a fire in the electrical wiring.

When selecting a 15 kW machine model for a three-phase load, you will need to take into account the parameters of the permissible voltage and current during a short circuit. It is worth focusing on the calculated current indicators of the cable with the minimum cross-section that protects the switch and the rated current of the receiver.

When calculating the input switching machine according to power parameters in a 380 V network, the following are taken into account:

electrical power – actual and additional;
cable loading intensity;
availability of free capacity in the design indicator of a residential building;
remoteness of outbuildings and non-residential premises from the cable entry point.

In a 15 kilowatt network with additional power, an ASU device is installed.

Sequence of correct installation of an electrical panel

To ensure that the electrical panel in your home is installed correctly, you should use only high-quality electrical products, as well as consumables. Only after installation is completed, operating voltage is supplied to the panel.

The correct assembly of a three-phase electrical panel has the following sequence:

Installation of an introductory machine. The device rating must cover the maximum power consumption. Since 3 phases will be brought into the house, the voltage between them will be 380 V, it is necessary to install a three-pole circuit breaker. To save money, it is not recommended to install 3 single-pole circuit breakers and connect them with a special strip. The input machine is installed in the upper left corner of the shield and is marked accordingly.
After the introductory machine, it is necessary to install an RCD. The rating of the device must correspond to the rating of the input switch. You should also pay attention to the cut-off current - the lower this indicator, the faster the RCD will turn off the network. There are differential circuit breakers that include protective functions against short circuits and shutdown the network when a leakage current occurs (RCD and standard switch). It is easier to use such a product, but its cost is quite high.
To the right of the RCD, at a short distance, a zero bus is mounted. Modern busbars provide a plastic dielectric between the copper strip and the shield body. This is done so that if the zero burns out and a phase gets on it, the electrical panel does not end up under life-threatening voltage.
Measuring instruments and voltage relays can also be placed on the strip with the input circuit breaker, RCD and zero bus. If you install a voltmeter and an ammeter in a three-phase network, then you must select products that display both linear and phase loads. And also capable of showing data on each phase separately.
The lower DIN rail contains automatic switches for power and lighting lines. In order not to get confused and not constantly look at the rating of the machines, lighting line products should be located at a short distance from the power switches.

After assembling the shield, you can mount it to the wall and connect the wires from consumers to the machines. An example of an electrical panel diagram, the number of machines can vary depending on the wishes of the owner.

If the electricity metering panel with a voltage of 380 V is not located on the street, then it is first installed in front of the input machine. But installing a device to monitor electricity consumption in the house is inconvenient, so inspectors (to save time and the absence of owners) must take readings on the street.

Functions of three-phase machines

Before choosing an automatic switch, you should understand its functionality. Users are often mistaken into thinking that the device protects household appliances. The machine does not respond to its electrical indicators, only triggering in the event of a short circuit or overload. The three-phase functions include:

simultaneous maintenance of several single-phase circuit zones;
preventing the formation of overcurrents on the line;
joint work with AC rectifiers;
protection of high-power equipment;
increased power due to the installation of a special converter;
fast response in short circuit mode on a line with a large number of consumers;
the ability to turn off manually using a switch or switch;
Compatible with optional safety terminals.

Without a automatic device, the risk of cable fire increases.

Operating principle and purpose of the circuit breaker

The three-phase circuit breaker is activated in case of a line fault using an electromagnetic switch. The principle of operation of the element is to heat the bimetallic plate at the moment the current rating increases and the voltage is turned off.

The fuse prevents short circuits and overcurrents with values higher than the calculated values from affecting the wiring. Without it, the cable cores heat up to the melting point, which leads to the ignition of the insulating layer. For this reason, it is important to know whether the network can handle the voltage.

Correspondence of wires to load

The problem is typical for old buildings, in which new machines, a meter, and an RCD are installed on the existing line. The machines are selected according to the overall power of the equipment, but sometimes they do not work - the cable smokes or burns.

For example, the cores of an old cable with a cross-section of 1.5 mm2 have a current limit of 19 A. If equipment with a total current of 22.7 A is turned on at a time, only a 25 Ampere modification will provide protection.

The wires will heat up, but the switch will remain turned on until the insulation melts. A fire can be prevented by completely replacing the wiring with a copper cable with a cross-section of 2.5 mm2.

Protecting the weakest section of cable wiring

Based on clause 3.1.4 of the PUE, the task of the automatic device is to prevent overload on the weakest link of the electrical circuit. Its rated current is selected based on the current of the connected household appliances.

If the machine is selected incorrectly, the unprotected area will cause a fire.

Principles for calculating the machine according to the cable cross-section

Calculations for a 3-phase automatic circuit breaker are carried out based on the cable cross-section. For a 25 A model, you will need to refer to the table.

Wire cross-section, mm2	Permissible load current based on cable material
Wire cross-section, mm2	Copper	Aluminum
0,75	11	8
1	15	11
1,5	17	13
2,5	25	19
4	35	28

The 25 Ampere modification can be used to protect wiring or installed at the input.

For example, a copper wire with a cross-section of 1.5 mm2 with a permissible load current of 19 A is used for wiring. To prevent the cable from heating up, you will need to select a lower value - 16 A.

Selection of automatic switch by power

Calculating the total power of household appliances will help you select a protective switch. You will need to look at the value in the device passport. For example, in the kitchen the following are plugged into the socket:

coffee maker – 1000 W;
electric oven – 2000 W;
microwave oven – 2000 W;
electric kettle – 1000 W;
refrigerator – 500 W.

Summing up the indicators, we get 6500 W or 6.5 kilowatts. Next, you will need to refer to the table of machines depending on the connection power.

Single-phase connection 220 V	Three-phase connection		Machine power
Single-phase connection 220 V	Delta circuit 380 V	Star circuit, 220 V	Machine power
3.5 kW	18.2 kW	10.6 kW	16 A
4.4 kW	22.8 kW	13.2 kW	20 A
5.5 kW	28.5 kW	16.5 kW	25 A
7 kW	36.5 kW	21.1 kW	32 A
8.8 kW	45.6 kW	26.4 kW	40 A

Based on the standard voltage wiring table, you can select a 32 A device that is suitable for a total power of 7 kW.

If you plan to connect additional equipment, an increase factor is used. The average value of 1.5 is multiplied by the power obtained from the calculations. A reduction factor is applied if it is impossible to operate several electrical appliances at the same time. It is equal to 1 or minus 1.

What elements does an electrical panel consist of?

It is necessary to purchase the components of the electrical panel immediately, so as not to subsequently waste time and not travel to the electrical store several times a day. The power of the shield is determined, it is 15 kW, which means that the maximum power consumption will not exceed 15 kW/h.

Electrical panel of a private house, list of elements:

Electric energy meter. The meter is the first element that must be installed in the panel. The best solution would be to purchase an electronic device designed to connect three phases. Such measuring instruments have high accuracy and a long service life. All information is displayed on a digital screen. Electronic meters can be programmed to operate in several tariffs.
Electrical shield. Now in stores there are a large number of electrical panels of various sizes and designed for a certain number of elements. The price of the product varies depending on the presence of a DIN rail, a built-in lock, as well as an inspection window (especially for taking readings from the meter). You should pay attention to protection from dust and moisture, its level should be at least IP 54. Dimensions - 445 × 400 × 150, and a wall thickness of 1 mm.
Input circuit breaker. You should purchase a three-pole machine, because the voltage supplied to the house will be 380 V, which means the presence of three phases.
Residual current device (RCD). It is required to be installed, since it is a protective element when a dangerous potential appears on the body of an electrical device.
Circuit breakers. The amperage should be selected based on the consumer load, which will be discussed below.
Voltage relay. Protects household electrical appliances from power surges. Many users install a relay, but it is not a required element. Also now widely used is the surge protection device (SPD). For example, when lightning strikes an overhead power line, the voltage in the house will reach high limits, which will be destructive for all equipment. The SPD will turn off the network in time, but, like the voltage relay, it is not installed often.
Read also: What are ampere hours and miliamp hours in a battery?
Measuring instruments. They are also an optional element of the electrical panel. Measuring instruments include ammeters and voltmeters, often combined into one product.

Selecting a machine depending on the load power

For apartments and houses with new electrical wiring, the choice of machine is made based on the calculated load current.

A three-phase type device can be calculated by the rated load current or by the response speed in conditions of exceeding the current value. For calculations, you need to add up the power of all consumers and calculate the current passing through the line. Work is performed according to the formula:

P – total power of all household appliances;
U – network voltage.

For example, the power is 7.2 kW, calculated using the formula 7200/220 = 32.72 A. The table shows ratings of 16, 20, 32, 25 and 40 A. The value is 32.72 A, taking into account the operation of the device at a value of 1 ,13 times more than the nominal value, multiply: 32x1.13=36.1 A. The table shows that it is better to install a 40 A model.

Methods for selecting a difavtomat

For example, consider a kitchen where a large amount of equipment is connected. First, you need to set the total power rating for a room with a refrigerator (500 W), microwave (1000 W), kettle (1500 W) and hood (100 W). The total power indicator is 3.1 kW. Based on it, various methods are used to select a 3-phase machine.

Table method

Based on the device table, a single-phase or three-phase device is selected based on the connection power. But the value in the calculations may not coincide with the tabular data. For a 3.1 kW network section, you will need a 16 A model - the closest value is 3.5 kW.

Graphical method

The selection technology is no different from the tabular one - you will need to find a schedule on the Internet. In the figure, the switches with their current load are shown horizontally, and the power consumption in one section of the circuit is shown vertically.

To establish the power of the device, you will need to draw a line horizontally to the point with the rated current. A total network load of 3.1 kW corresponds to a 16 A switch.

Formula for calculating the power of electric current

According to Ohm's law, current (I) is proportional to voltage (U) and inversely proportional to resistance (R), and power (P) is calculated as the product of voltage and current. Based on this, the current in the network section is calculated: I = P/U.

In real conditions, one more component is added to the formula and the formula for a single-phase network takes the form:

I = P/(U*cos φ),

and for a three-phase network: I = P/(1.73*U*cos φ),

where U for a three-phase network is assumed to be 380 V, cos φ is the power factor, reflecting the ratio of the active and reactive components of the load resistance.

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For modern power supplies, the reactive component is insignificant; the value of cos φ can be taken equal to 0.95. The exception is powerful transformers (for example, welding machines) and electric motors; they have high inductive reactance. In networks where it is planned to connect such devices, the maximum current should be calculated using a cos φ coefficient of 0.8, or the current should be calculated using the standard method, and then a multiplying factor of 0.95/0.8 = 1.19 should be applied.

Substituting the effective voltage values of 220 V/380 V and a power factor of 0.95, we obtain I = P/209 for a single-phase network and I = P/624 for a three-phase network, that is, in a three-phase network with the same load, the current is three times less. There is no paradox here, since three-phase wiring provides three phase wires, and with a uniform load on each phase it is divided into three. Since the voltage between each phase and working neutral wires is 220 V, the formula can be rewritten in another form, so it is more clear: I = P/(3*220*cos φ).

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Nuances to consider

No one can know exactly what household appliances will be in a house or apartment. For this reason you should:

increase the total calculated power of a three-phase automatic circuit breaker by 50%, or apply an increase factor of 1.5;
a reduction factor is taken into account when there are not enough sockets in the room to simultaneously connect equipment;
to simplify calculations, the load should be divided into groups;
powerful devices should be connected separately, taking into account the low-power load;
to calculate a low-power load, you will need to divide the power by the voltage;
wiring is the main factor that is taken into account when choosing a 3-phase automatic switch; old aluminum wires can withstand 10 A, but if taken for 16 A sockets, they can melt;
in domestic conditions, models with current ratings of 6, 16, 25, 32 and 40 A are most often used.

When purchasing a three-phase differential circuit breaker, you need to take into account that the main markings are on the case or in the passport. Using formulas and tables will help you choose a model in accordance with the wiring in the apartment and the power of household appliances.

Basic functions of machines

Before choosing an automatic protective device, you need to understand the principles of its operation and capabilities. Many people consider the main function of the machine to be the protection of household appliances. However, this judgment is absolutely wrong. The machine does not react in any way to devices connected to the network; it is triggered only during short circuits or overloads. These critical conditions lead to a sharp increase in current strength, causing overheating and even fire of cables.

A special increase in current strength is observed during a short circuit. At this moment, its value increases to several thousand amperes and the cables are simply not able to withstand such a load, especially if its cross-section is 2.5 mm2. With such a cross-section, an instant fire occurs in the wire.

Therefore, a lot depends on the correct choice of machine. Accurate calculations, including power calculations, make it possible to reliably protect the electrical network.

Machine calculation parameters

Each circuit breaker primarily protects the wiring connected downstream of it. Basic calculations of these devices are carried out based on the rated load current. Power calculations are carried out in the case when the entire length of the wire is designed to carry the load, in accordance with the rated current.

The final choice of rated current for the machine depends on the cross-section of the wire. Only after this can the load value be calculated. The maximum current allowed for a wire with a certain cross-section must be greater than the rated current indicated on the machine. Thus, when choosing a protective device, the minimum wire cross-section present in the electrical network is used.

When consumers have a question about which machine should be installed at 15 kW, the table also takes into account the three-phase electrical network. There is a methodology for such calculations. In these cases, the rated power of a three-phase circuit breaker is determined as the sum of the powers of all electrical appliances planned to be connected through the circuit breaker.

How to connect three phases

Of course, before moving on to the technical side of the issue and directly to the connection, you need to contact the company that is the electricity supplier in this particular region. To do this, the customer must clearly understand and agree on the following points:

Network power.
Meter type and tariff. This can be a multi-tariff meter or a single-tariff one.
Number of phases (in this case 3).
Connection diagram.
Organization of grounding, which is extremely necessary to protect people from electric current in the event of breakdown or deterioration of insulation resistance.

Important! Self-connection to power grids is prohibited by law! The procedure for connecting and organizing power supply must be performed by highly qualified personnel. In order to connect a private house to a three-phase network, it must be completely de-energized, and doing this without an energy service is also prohibited.

Suppliers adhere to clear requirements and rules. Therefore, if the distance from a private house to 380 Volt networks, most often passing through poles, is more than 300 meters within the city (500 outside the city), then in order to conduct electricity you will also have to pay for the installation of a support.

The next key issue in connecting a home to a 380 Volt network will be the power that the consumer will take from the network.

Of course, it is better to organize power supply with a power reserve, especially since the increase in the number of devices that operate on this type of energy is still obvious. However, the cost of this system will be higher.

The list of documents required to connect 380 Volts (in addition to the application itself) includes:

Identification.
Law-abiding taxpayer identification number.
Title documentation for residential or non-residential premises (in case of connecting a garage).
Approved complete residential plan (if available).

A copy is made of these documents and submitted to the company's electricity supplier. However, verification with the originals is also required.

Some suppliers may also request additional documents, just in case, you should also take them with you:

Information about power and a list of all available electrical equipment in a private home, garage or country house. Depending on where three-phase electricity needs to be routed. If the connection is made to an area that does not have electrical equipment, then you will have to indicate its estimated types and power.
Information about their maximum power.
Approximate time of commissioning of housing, if it is not yet a residential property.

How to conduct 380 Volts in a private house and what documents are needed

Suitable for electric motors with a rotation speed of up to 3000 rpm and for motors with increased resistance at start-up.

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Which machine is 15 kW 1 phase, 15 kilowatts, how many amperes | Glory to the creators For motors with a power of up to 3 kilowatts and used at home, the price of starting capacitors is high and sometimes comparable to the cost of the motor itself. Ask, I'm in touch!

Basic functions of machines

Therefore, a lot depends on the correct choice of machine. Accurate calculations, including power calculations, make it possible to reliably protect the electrical network.

How to convert watt to ampere

You need to convert watts to amperes in a situation where you need to install a protective device and you need to choose what rated current it should have. It is clear from the operating instructions how many watts a household appliance connected to a single-phase network consumes.

If you connect several devices simultaneously to one protection device, then in order to calculate how many amperes there are in watts, you need to add all the consumption values together. For example, the room uses lighting with 10 pcs LED lamps. 6 W, iron 2 kW and TV 30 W. First, all indicators need to be converted into watts, it turns out:

Now you can convert amperes to watts, to do this we substitute the values in the formula 2090/220 V = 9.5 A ~ 10 A. Answer: current consumption is about 10 A.

You need to know how to convert amps to watts without a calculator. The table shows the correspondence between the rate of electricity consumption and the current strength for single-phase and three-phase networks.

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Installation cost The design of the box, the location of the terminals and their shape may differ, so it is better to select standard models so that, if necessary, you can freely find a replacement. Ask, I'm in touch!

Machine calculation parameters

For example, if the load of each of the three phases is 5 kW, then the operating current is determined by multiplying the sum of the powers of all phases by a factor of 1.52. Thus, it turns out 5x3x1.52 = 22.8 amperes. The rated current of the machine must exceed the operating current. In this regard, the most suitable protective device would be rated 25 A. The most common ratings of circuit breakers are 6, 10, 16, 20, 25, 32, 40, 50, 63, 80 and 100 amperes. At the same time, the compliance of the cable cores with the declared loads is clarified.

This technique can be used only in cases where the load is the same on all three phases. If one of the phases consumes more power than all the others, then the rating of the circuit breaker is calculated based on the power of this particular phase. In this case, only the maximum power value is used, multiplied by a factor of 4.55. These calculations allow you to select a machine not only according to the table, but also according to the most accurate data obtained.

Phase imbalance

In fact, distributing the load across phases in a private house, performed with phase imbalance, does not pose serious problems for equipment. But you are guaranteed to periodically turn off the circuit breaker.

Before distributing the load, it is necessary to understand the structure of the three-pole circuit breaker. Let's consider the situation using the example of the C 25 machine. It consists of 3 single-phase machines, each of which can withstand 25 A. Thus, each phase receives 5 kW of power, which means that connecting a cottage with a power of 15 kW. In this case, the machines can interrupt the power with one switch (lever).

An example of load distribution on a three-phase power supply for a cottage Source mastergrad.com

If you are considering the question of how to distribute the load across phases in a random (chaotic) order, pay attention to the following example:

Phase No. 1 is connected to the lighting of the cottage.
Phase No. 2 supplies power to the 1st floor outlets.
Phase No. 3 powers the outlets on the 2nd floor.

As a result, the following will happen:

On the 2nd floor there are several bedrooms and a bathroom. There are no powerful energy consumers here. As a result, Phase 3 will not operate at full capacity.
A similar situation will occur with phase No. 1. Modern LED lighting consumes little electricity.
The last phase No. 2 will be overloaded, due to the fact that the main, powerful consumers are “hung” on it: a washing machine, a microwave oven, a refrigerator and other equipment located in the premises of the first floor.

Important! As a result, the simultaneous inclusion of several elements of household appliances will overload the machine, which will result in its shutdown.