Not every average person understands what electrical circuits are. In apartments they are 99% single-phase, where the current flows to the consumer through one wire and returns through the other (zero). A three-phase network is a system for transmitting electric current that flows through three wires and returns one at a time. Here the return wire is not overloaded due to the phase shift of the current. Electricity is generated by a generator driven by an external drive.
An increase in the load in the circuit leads to an increase in the current passing through the generator windings. As a result, the magnetic field resists rotation of the drive shaft to a greater extent. The number of revolutions begins to decrease and commands an increase in drive power, for example by supplying more fuel to the internal combustion engine. The speed is restored and more electricity is generated.
A three-phase system consists of 3 circuits with an EMF of the same frequency and a phase shift of 120°.
Features of connecting power to a private home
Many people believe that a three-phase network in the house increases power consumption. In fact, the limit is set by the electricity supply organization and is determined by the following factors:
- supplier capabilities;
- number of consumers;
- condition of the line and equipment.
To prevent voltage surges and phase imbalance, they should be loaded evenly. The calculation of a three-phase system is approximate, since it is impossible to accurately determine which devices will be connected at a given moment. The presence of pulsed devices currently leads to increased energy consumption during their startup.
The electrical distribution panel for a three-phase connection is larger in size than for a single-phase supply. Options are possible with the installation of a small input panel, and the rest made of plastic for each phase and for outbuildings.
Connection to the main line is carried out using underground and overhead lines. Preference is given to the latter due to the small amount of work, low connection cost and ease of repair.
Nowadays it is convenient to make an air connection using a self-supporting insulated wire (SIP). The minimum cross-section of the aluminum core is 16 mm 2, which is sufficient for a private home.
The SIP is attached to the supports and the wall of the house using anchor brackets with clamps. The connection to the main overhead line and the input cable to the electrical panel of the house is made with branch piercing clamps. The cable is taken with non-combustible insulation (VVGng) and passed through a metal pipe inserted into the wall.
Air connection of three-phase power supply at home
At a distance from the nearest support, it is more necessary to install another pole. This is necessary to reduce loads that lead to sagging or broken wires.
The height of the connection point is 2.75 m and above.
Electrical distribution cabinet
Connection to a three-phase network is made according to the project, where inside the house consumers are divided into groups:
- lighting;
- sockets;
- separate powerful devices.
Some loads can be disconnected for repairs while others are running.
The power of consumers is calculated for each group, where the wire of the required cross-section is selected: 1.5 mm 2 - for lighting, 2.5 mm 2 - for sockets and up to 4 mm 2 - for powerful devices.
The wiring is protected from short circuits and overloads by circuit breakers.
Electric meter
For any connection scheme, a metering device is required. A 3-phase meter can be connected directly to the network (direct connection) or through a voltage transformer (semi-indirect), where the meter readings are multiplied by a coefficient.
It is important to follow the connection order, where odd numbers are power and even numbers are load. The color of the wires is indicated in the description, and the diagram is located on the back cover of the device. The input and corresponding output of a 3-phase meter are indicated by the same color. The most common connection order is when the phases come first and the last wire is zero.
A 3-phase direct connection meter for a home is usually designed for a power of up to 60 kW.
Before choosing a multi-tariff model, you should coordinate the issue with the energy supply company. Modern devices with tarifficators make it possible to calculate electricity charges depending on the time of day, register and record power values over time.
The temperature readings of the devices are selected as widely as possible. On average they range from -20 to +50 °C. The service life of the devices reaches 40 years with a calibration interval of 5-10 years.
The meter is connected after the input three- or four-pole circuit breaker.
Three-phase load
Consumers include electric boilers, asynchronous electric motors and other electrical appliances. The advantage of using them is the uniform distribution of the load in each phase. If a three-phase network contains unevenly connected single-phase powerful loads, this can lead to phase imbalance. At the same time, electronic devices begin to malfunction, and lighting lamps glow dimly.
Connection diagram of a three-phase motor to a three-phase network
The operation of three-phase electric motors is characterized by high performance and efficiency. No additional starting devices are required here. For normal operation, it is important to connect the device correctly and follow all recommendations.
The connection diagram of a three-phase motor to a three-phase network creates a rotating magnetic field with three windings connected in a star or delta.
Each method has its own advantages and disadvantages. The star circuit allows the engine to start smoothly, but its power is reduced by up to 30%. This loss is absent in the delta circuit, but the current load is significantly greater at start-up.
The motors have a connection box where the winding terminals are located. If there are three of them, then the circuit is connected only by a star. With six terminals, the motor can be connected in any way.
Power consumption
It is important for the home owner to know how much energy is consumed. This is easy to calculate for all electrical appliances. Adding up all the powers and dividing the result by 1000, we get the total consumption, for example 10 kW. For household electrical appliances, one phase is sufficient. However, current consumption increases significantly in a private home where there is powerful equipment. One device can have 4-5 kW.
It is important to plan the power consumption of a three-phase network at the design stage in order to ensure symmetry in voltages and currents.
A four-wire wire with three phases and a neutral enters the house. The voltage of the electrical network is Between the phases and the neutral wire, electrical appliances are connected to In addition, there may be a three-phase load.
The power calculation of a three-phase network is carried out in parts. First, it is advisable to calculate purely three-phase loads, for example a 15 kW electric boiler and a 3 kW asynchronous electric motor. The total power will be P = 15 + 3 = 18 kW. In this case, current I = Px1000/(√3xUxcosϕ) flows in the phase wire. For household electrical networks cosϕ = 0.95. Substituting numerical values into the formula, we obtain the current value I = 28.79 A.
Now you need to define single-phase loads. Let them be P A = 1.9 kW, P B = 1.8 kW, P C = 2.2 kW for the phases. The mixed load is determined by summation and is 23.9 kW. The maximum current will be I = 10.53 A (phase C). Adding it to the current from the three-phase load, we get I C = 39.32 A. The currents in the remaining phases will be I B = 37.4 kW, I A = 37.88 A.
When calculating the power of a three-phase network, it is convenient to use power tables taking into account the type of connection.
Using them it is convenient to select circuit breakers and determine wiring cross-sections.
Conclusion
With proper design and maintenance, a three-phase network is ideal for a private home. It allows you to evenly distribute the load across phases and connect additional power from electrical consumers, if the wiring cross-section allows.
So, why do some electrical panels receive a voltage of 380 V, and some - 220? Why do some consumers have three-phase voltage, while others have single-phase? There was a time when I asked myself these questions and looked for answers to them. Now I’ll tell you in a popular way, without the formulas and diagrams that textbooks abound.
In other words. If one phase approaches the consumer, then the consumer is called single-phase, and its supply voltage will be 220 V (phase). If they talk about three-phase voltage, then we are always talking about a voltage of 380 V (linear). Who cares? More details below.
How are three phases different from one?
In both types of power there is a working neutral conductor (ZERO). I'm talking about protective grounding, this is a broad topic. In relation to zero in all three phases - the voltage is 220 Volts. But in relation to these three phases to each other, they have 380 Volts.
Voltages in a three-phase system
This happens because the voltages (with an active load, and the current) on the three phase wires differ by a third of the cycle, i.e. at 120°.
You can read more in the electrical engineering textbook - about voltage and current in a three-phase network, and also see vector diagrams.
It turns out that if we have three-phase voltage, then we have three phase voltages of 220 V each. And single-phase consumers (and there are almost 100% of them in our homes) can be connected to any phase and zero. You just need to do this in such a way that the consumption in each phase is approximately the same, otherwise phase imbalance is possible.
In addition, it will be difficult for the overly loaded phase and it will be offensive that others are “resting”)
Advantages and disadvantages
Both power systems have their pros and cons, which change places or become insignificant when the power passes the 10 kW threshold. I'll try to list.
Single-phase network 220 V, advantages
- Simplicity
- Cheapness
- Below dangerous voltage
Single-phase network 220 V, cons
- Limited consumer power
Three-phase network 380 V, advantages
- Power is limited only by wire cross-section
- Savings with three-phase consumption
- Power supply for industrial equipment
- Possibility of switching a single-phase load to a “good” phase in case of deterioration in quality or power failure
Three-phase network 380 V, cons
- More expensive equipment
- More dangerous voltage
- Limits the maximum power of single-phase loads
When is it 380 and when is it 220?
So why do we have a voltage of 220 V in our apartments and not 380? The fact is that, as a rule, consumers with a power of less than 10 kW are connected to one phase. This means that one phase and a neutral (zero) conductor are introduced into the house. This is exactly what happens in 99% of apartments and houses.
Single-phase electrical panel in the house. The right machine is introductory, then through the rooms. Who can find mistakes in the photo? Although, this shield is one big mistake...
However, if you plan to consume power more than 10 kW, then a three-phase input is better. And if you have equipment with three-phase power supply (containing), then I strongly recommend introducing a three-phase input into the house with a linear voltage of 380 V. This will save on wire cross-section, on safety, and on electricity.
Despite the fact that there are ways to connect a three-phase load to a single-phase network, such modifications sharply reduce the efficiency of motors, and sometimes, all other things being equal, you can pay 2 times more for 220 V than for 380.
Single-phase voltage is used in the private sector, where power consumption, as a rule, does not exceed 10 kW. In this case, a cable with wires with a cross section of 4-6 mm² is used at the input. The current consumption is limited by the input circuit breaker, the rated protection current of which is no more than 40 A.
I’ve already talked about choosing a circuit breaker. And about the choice of wire cross-section -. There are also heated discussions of issues.
But if the consumer’s power is 15 kW or higher, then three-phase power must be used. Even if there are no three-phase consumers in this building, for example, electric motors. In this case, the power is divided into phases, and the electrical equipment (input cable, switching) does not bear the same load as if the same power was taken from one phase.
For example, 15 kW is about 70A for one phase; you need a copper wire with a cross-section of at least 10 mm². The cost of a cable with such cores will be significant. But I have never seen single-phase (single-pole) circuit breakers with a current greater than 63 A on a DIN rail.
Therefore, in offices, stores, and especially in enterprises, only three-phase power is used. And, accordingly, three-phase meters, which come in direct connection and transformer connection (with current transformers).
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And at the input (in front of the counter) there are approximately the following “boxes”:
Three-phase input. Introductory machine in front of the counter.
A significant disadvantage of three-phase input and (noted above) – limitation on the power of single-phase loads. For example, the allocated power of three-phase voltage is 15 kW. This means that for each phase - a maximum of 5 kW. This means that the maximum current in each phase is no more than 22 A (practically 25). And you have to spin, distributing the load.
I hope it is now clear what three-phase voltage 380 V and single-phase voltage 220 V are?
Star and Delta circuits in a three-phase network
There are various variations for connecting a load with an operating voltage of 220 and 380 Volts to a three-phase network. These patterns are called “Star” and “Triangle”.
When the load is designed for a voltage of 220V, it is connected to a three-phase network according to the “Star” circuit, that is, to phase voltage. In this case, all load groups are distributed so that the powers in the phases are approximately equal. The zeros of all groups are connected together and connected to the neutral wire of the three-phase input.
All our apartments and houses with single-phase input are connected to “Zvezda”; another example is the connection of heating elements in powerful and.
When the load has a voltage of 380V, it is switched on according to the “Triangle” circuit, that is, to linear voltage. This phase distribution is most typical for electric motors and other loads where all three parts of the load belong to a single device.
Power distribution system
Initially, the voltage is always three-phase. By “initially” I mean a generator at a power plant (thermal, gas, nuclear), from which a voltage of many thousands of volts is supplied to step-down transformers, which form several voltage stages. The last transformer lowers the voltage to a level of 0.4 kV and supplies it to end consumers - you and me, apartment buildings and the private residential sector.
Next, the voltage is supplied to the second stage transformer TP2, at the output of which the end-user voltage is 0.4 kV (380V). The power of transformers TP2 is from hundreds to thousands of kW. From TP2, voltage is supplied to us - to several apartment buildings, to the private sector, etc.
The circuit is simplified, there may be several steps, the voltage and power may be different, but the essence does not change. There is only one final voltage of consumers - 380 V.
Photo
Finally, a few more photos with comments.
Electrical panel with three-phase input, but all consumers are single-phase.
Friends, that’s all for today, good luck to everyone!
I look forward to your feedback and questions in the comments!
Content:The operation of three-phase electric motors is considered to be much more efficient and productive than single-phase motors designed for 220 V. Therefore, if there are three phases, it is recommended to connect the appropriate three-phase equipment. As a result, connecting a three-phase motor to a three-phase network ensures not only economical, but also stable operation of the device. The connection diagram does not require the addition of any starting devices, since immediately after starting the engine, a magnetic field is formed in its stator windings. The main condition for the normal operation of such devices is the correct connection and compliance with all recommendations.
Connection diagrams
The magnetic field created by the three windings ensures the rotation of the electric motor rotor. Thus, electrical energy is converted into mechanical energy.
The connection can be made in two main ways - star or triangle. Each of them has its own advantages and disadvantages. The star circuit provides a smoother start of the unit, however, the engine power drops by about 30% of the rated value. In this case, the delta connection has certain advantages, since there is no loss of power. However, this also has its own peculiarity associated with the current load, which increases sharply during startup. This condition has a negative impact on the insulation of wires. The insulation may be broken and the motor may fail completely.
Particular attention should be paid to European equipment equipped with electric motors designed for voltages of 400/690 V. They are recommended for connection to our 380 volt networks only using the delta method. If connected with a star, such motors immediately burn out under load. This method is applicable only to domestic three-phase electric motors.
Modern units have a connection box into which the ends of the windings are led out. Their number can be three or six. In the first case, the connection diagram is initially assumed to be a star method. In the second case, the electric motor can be connected to a three-phase network in both ways. That is, with a star circuit, the three ends located at the beginning of the windings are connected into a common twist. The opposite ends are connected to the phases of the 380 V network from which power is supplied. With the triangle option, all ends of the windings are connected in series to each other. The phases are connected to three points at which the ends of the windings are connected to each other.
Using a star-delta circuit
A combined connection diagram known as “star-delta” is used relatively rarely. It allows for a smooth start with a star circuit, and during the main operation a triangle is turned on, providing maximum power to the unit.
This connection diagram is quite complex, requiring the use of three windings installed in the connections at once. The first MP is connected to the network and with the ends of the windings. MP-2 and MP-3 are connected to opposite ends of the windings. The delta connection is made to the second starter, and the star connection is made to the third. Simultaneous activation of the second and third starters is strictly prohibited. This will cause a short circuit between the phases connected to them. To prevent such situations, an interlock is installed between these starters. When one MP turns on, the contacts of the other open.
The entire system operates according to the following principle: simultaneously with MP-1 being turned on, MP-3, connected by a star, is turned on. After a smooth start of the engine, after a certain period of time set by the relay, the transition to normal operating mode occurs. Next, MP-3 is turned off and MP-2 is turned on according to a triangle diagram.
Three-phase motor with magnetic starter
Connecting a three-phase motor using a magnetic starter is carried out in the same way as through a circuit breaker. This circuit is simply supplemented with an on/off block with corresponding START and STOP buttons.
One normally closed phase connected to the motor is connected to the START button. When pressed, the contacts close, after which current flows to the motor. However, it should be noted that if the START button is released, the contacts will be open and no power will be supplied. To prevent this, the magnetic starter is equipped with another additional contact connector, the so-called self-retaining contact. It functions as a locking element and prevents the circuit from breaking when the START button is turned off. The circuit can only be completely disconnected using the STOP button.
Thus, connecting a three-phase motor to a three-phase network can be done in various ways. Each of them is selected in accordance with the unit model and specific operating conditions.
In the household, sometimes there is a need to run a 3-phase asynchronous electric motor (AM). If you have a 3-phase network, this is not difficult. In the absence of a 3-phase network, the engine can be started from a single-phase network by adding capacitors to the circuit.
Structurally, the IM consists of a stationary part - the stator, and a moving part - the rotor. Windings are placed in slots on the stator. The stator winding is a three-phase winding, the conductors of which are evenly distributed around the circumference of the stator and laid in phases in slots with an angular distance of 120 el. degrees. The ends and beginnings of the windings are led out into the junction box. The windings form pairs of poles. The rated rotor speed of the motor depends on the number of pole pairs. Most general industrial motors have 1-3 pairs of poles, less often 4. IMs with a large number of pole pairs have low efficiency, larger dimensions, and therefore are rarely used. The more pole pairs, the lower the motor rotor speed. General industrial motors are produced with a number of standard rotor speeds: 300, 1000, 1500, 3000 rpm.
The rotor of the IM is a shaft on which there is a short-circuited winding. In low- and medium-power motors, the winding is usually made by pouring molten aluminum alloy into the grooves of the rotor core. Together with the rods, short-circuited rings and end blades are cast, which ventilate the machine. In high-power machines, the winding is made of copper rods, the ends of which are connected to short-circuited rings by welding.
When the IM is turned on in a 3-phase network, current begins to flow through the windings in turn at different times. In one period of time, the current passes along the pole of phase A, in another along the pole of phase B, in the third along the pole of phase C. Passing through the poles of the windings, the current alternately creates a rotating magnetic field that interacts with the rotor winding and causes it to rotate, as if pushing it in different planes at different times.
If you turn on the IM in a 1-phase network, the torque will be created by only one winding. Such a moment will act on the rotor in one plane. This moment is not enough to move and rotate the rotor. To create a phase shift of the pole current relative to the supply phase, phase-shifting capacitors are used in Fig. 1.
Capacitors can be used of any type, except electrolytic. Capacitors such as MBGO, MBG4, K75-12, K78-17 are well suited. Some capacitor data is shown in Table 1.
If it is necessary to gain a certain capacitance, then the capacitors should be connected in parallel.
The main electrical characteristics of the IM are given in the data sheet, Fig. 2.
Fig.2
From the passport it is clear that the motor is three-phase, with a power of 0.25 kW, 1370 rpm, it is possible to change the winding connection diagram. The connection diagram for the windings is “triangle” at a voltage of 220V, “star” at a voltage of 380V, respectively, the current is 2.0/1.16A.
The star connection diagram is shown in Fig. 3. With this connection, a voltage is supplied to the electric motor windings between points AB (linear voltage U l) that is times greater than the voltage between points AO (phase voltage U f).
Fig.3 Star connection diagram.
Thus, the linear voltage is several times greater than the phase voltage: . In this case, the phase current I f is equal to the linear current I l.
Let's look at the triangle connection diagram in Fig. 4:
Fig.4 Delta connection diagram
With such a connection, the linear voltage U L is equal to the phase voltage U f., and the current in the line I l is times greater than the phase current I f:.
Thus, if the IM is designed for a voltage of 220/380 V, then to connect it to a phase voltage of 220 V, a “triangle” connection diagram for the stator windings is used. And for connection to a linear voltage of 380 V - a star connection.
To start this IM from a single-phase network with a voltage of 220V, we should turn on the windings according to the “delta” circuit, Fig. 5.
Fig.5 Connection diagram of the EM windings according to the “triangle” diagram
The connection diagram of the windings in the output box is shown in Fig. 6
Fig.6 Connection in the ED output box according to the “triangle” diagram
To connect an electric motor according to the “star” circuit, it is necessary to connect two phase windings directly to a single-phase network, and the third through a working capacitor C p to any of the network wires in Fig. 6.
The connection in the terminal box for the star circuit is shown in Fig. 7.
Fig. 7 Connection diagram of the EM windings according to the “star” scheme
The connection diagram of the windings in the output box is shown in Fig. 8
Fig.8 Connection in the ED output box according to the “star” scheme
The capacity of the working capacitor C p for these circuits is calculated by the formula:
,
where I n - rated current, U n - rated operating voltage.
In our case, to switch on the “triangle” circuit, the capacitance of the working capacitor is C p = 25 µF.
The operating voltage of the capacitor must be 1.15 times the rated voltage of the supply network.
To start an IM of small power, a working capacitor is usually sufficient, but with a power of more than 1.5 kW, the engine either does not start or picks up speed very slowly, so it is necessary to also use a starting capacitor C p. The capacity of the starting capacitor should be 2.5-3 times greater than the capacity of the working capacitor capacitor.
The connection diagram of the electric motor windings connected in a delta pattern using starting capacitors C p is shown in Fig. 9.
Fig. 9 Connection diagram of the EM windings according to the “triangle” diagram using starting condensates
The connection diagram of the star motor windings using starting capacitors is shown in Fig. 10.
Fig. 10 Connection diagram of the EM windings according to the “star” circuit using starting capacitors.
Starting capacitors C p are connected in parallel to the working capacitors using the KN button for a time of 2-3 s. In this case, the rotation speed of the electric motor rotor should reach 0.7…0.8 of the rated rotation speed.
To start the IM using starting capacitors, it is convenient to use the button Fig. 11.
Fig.11
Structurally, the button is a three-pole switch, one pair of contacts of which closes when the button is pressed. When released, the contacts open, and the remaining pair of contacts remains on until the stop button is pressed. The middle pair of contacts performs the function of a KN button (Fig. 9, Fig. 10), through which starting capacitors are connected, the other two pairs act as a switch.
It may turn out that in the connection box of the electric motor the ends of the phase windings are made inside the motor. Then the IM can only be connected according to the diagrams in Fig. 7, Fig. 10, depending on power.
There is also a diagram for connecting the stator windings of a three-phase electric motor - partial star Fig. 12. Making a connection according to this diagram is possible if the beginnings and ends of the stator phase windings are brought out into the junction box.
Fig.12
It is advisable to connect an electric motor according to this scheme when it is necessary to create a starting torque exceeding the nominal one. This need arises in drives of mechanisms with difficult starting conditions, when starting mechanisms under load. It should be noted that the resulting current in the supply wires exceeds the rated current by 70-75%. This must be taken into account when choosing the wire cross-section for connecting the electric motor.
Capacitance of the working capacitor C p for the circuit in Fig. 12 is calculated by the formula:
.
The capacitance of starting capacitors should be 2.5-3 times greater than the capacitance C r. The operating voltage of the capacitors in both circuits should be 2.2 times the rated voltage.
Typically, the terminals of the stator windings of electric motors are marked with metal or cardboard tags indicating the beginnings and ends of the windings. If for some reason there are no tags, proceed as follows. First, the belonging of the wires to the individual phases of the stator winding is determined. To do this, take any of the 6 external terminals of the electric motor and connect it to any power source, and connect the second terminal of the source to the control light and, with the second wire from the lamp, alternately touch the remaining 5 terminals of the stator winding until the light comes on. When the light comes on, it means that the 2 terminals belong to the same phase. Conventionally, let's mark the beginning of the first wire C1 with tags, and its end - C4. Similarly, we will find the beginning and end of the second winding and designate them C2 and C5, and the beginning and end of the third - C3 and C6.
The next and main stage will be to determine the beginning and end of the stator windings. To do this, we will use the selection method, which is used for electric motors with a power of up to 5 kW. Let's connect all the beginnings of the phase windings of the electric motors according to the previously connected tags to one point (using a star circuit) and connect the electric motor to a single-phase network using capacitors.
If the engine immediately picks up the rated speed without a strong hum, this means that all the beginnings or all ends of the winding have hit the common point. If, when turned on, the engine hums strongly and the rotor cannot reach the rated speed, then terminals C1 and C4 in the first winding should be swapped. If this does not help, the ends of the first winding must be returned to their original position and now the terminals C2 and C5 are swapped. Do the same; for the third pair if the engine continues to hum.
When determining the beginnings and ends of windings, strictly adhere to safety regulations. In particular, when touching the stator winding clamps, hold the wires only by the insulated part. This must also be done because the electric motor has a common steel magnetic core and a large voltage may appear at the terminals of other windings.
To change the direction of rotation of the rotor of an IM connected to a single-phase network according to the “triangle” circuit (see Fig. 5), it is enough to connect the third phase winding of the stator (W) through a capacitor to the terminal of the second phase winding of the stator (V).
To change the direction of rotation of an IM connected to a single-phase network according to the “star” circuit (see Fig. 7), you need to connect the third phase winding of the stator (W) through a capacitor to the terminal of the second winding (V).
When checking the technical condition of electric motors, you can often notice with disappointment that after prolonged operation, extraneous noise and vibration appear, and the rotor is difficult to turn manually. The reason for this may be the poor condition of the bearings: the treadmills are covered with rust, deep scratches and dents, individual balls and the cage are damaged. In all cases, it is necessary to inspect the electric motor and eliminate any existing faults. In case of minor damage, it is enough to wash the bearings with gasoline and lubricate them.
For single-family houses it is better without division!Why, wrote in the topic .
The conductor passing through the meter cannot be divided and grounded! This is not to mention the stupidity of installing additional buses in the control room N , adding completely unjustified 2-pin connections. There are no cultural words at all about the socket in the control room, so connected. This is not to say that by default there should be no sockets at all on a pole or pipe stand in the control room.
In the most extreme case, as an exception, it is possible to ground after the meter, but only if the neutral pole of the meter is tightly short-circuited and not with the same cross-section as in the photo and only for the control room on a pole or pipe stand.
If there is still a division, then instead of a machine after the meter there must be a VDT, so that there is at least some protection in case of a violation of the integrity of the PE circuit between the control room and the house!
SP 31-110-2003 said:
Poor power supply continuity at home!A. 2.1 Residual current-controlled residual current devices, along with overcurrent protection devices, are the main types of protection against indirect contact, providing automatic power shutdown.
A. 2.2 Overcurrent protection provides protection against indirect contact by disconnecting the damaged section of the circuit in the event of a solid short circuit to the housing. At low fault currents, a decrease in the insulation level, and also when the neutral protective conductor breaks, the RCD is, in fact, the only means of protection.
PUE-7 Russia said:
1.1.17. To indicate the mandatory compliance with the requirements of the PUE, the words "must", "should", "necessary" and derivatives from them. ...What is aggravated by the fact that in most of the scheme is usedworstmethod of using differential protection!7.1.73. When installing an RCD in seriesmustselectivity requirements are met. With two- and multi-stage circuits, the RCD located closer to the power sourcemusthave a setting and response time no less than 3 times greater than that of the RCD located closer to the consumer.
PUE-7 Russia said:
1.1.17. ... The word “allowed” means that this decision is applied as an exception as forced (due to cramped conditions, limited resources of necessary equipment, materials, etc.). ...What is further aggravated by the use where it is usedworstmethod of using differential protection of 1P machine guns, not 2P or 1P+ N machines!Which increases the likelihood, instead of eliminating the accident, of stupid exclusion from the circuit by you or by an equally illiterate electrical/fire safety electrician, for example, as described in the topic thatdangerous, becauseThere will be no protective shutdown at all!7.1.79. … Allowedconnection to one RCD of several group lines through separate circuit breakers (fuses). ...
Where the best method of applying differential protection is applied, group ABs are not positioned correctly relative to group RCCBs!
PUE-7 Russia said:
1.1.17. To indicate the mandatory compliance with the requirements of the PUE, the words “must”, “should”, “necessary” and derivatives from them are used. The words “as a rule” mean that this requirement is predominant, and deviation from it must be justified. ...SP 31-110-2003 said:
This Code of Rules specifies and develops the requirements of regulatory documents, including the series of standards GOST R 50571.1 - GOST R 50571.18 and the new Rules for the Construction of Electrical Installations (PUE seventh edition).A. 1.1 For protection against electric shock, an RCD,usually, mustused in separate group lines. ...
If there are lamps controlled by 2-key switches, some types of dimmers, then you will need another 4x1.5 mm2 cable, and in some cases 5x1.5 mm2.
Partial selectivity is allowed in one panel, but it is better to avoid it, as well as installing a common RCCB not in the control room, but in the house, especially when there is a jamb with 1P circuit breakers atthe worstmethod of applying differential protection.
No, for forced non-emergency de-energization it is possible only with incoming AV and only without load.
The AB rating for the hob is greatly overestimated!
A 10 mA RCCB with such an operating current is difficult to purchase.
Apart from the street, the submersible pump characteristic C of group AB is most likely not needed.
Group circuit breakers on ordinary household sockets with characteristic C should be installed only if necessary, where electrical appliances without a soft start with a power of ≥1000 watts will be connected, for example in a workshop, on the street, as well as on electrical appliances without a soft start with a lower power, if the rating of the machine It is installed in close proximity to the power of the electrical appliance, so that in addition to protecting the wiring, it also protects the electrical appliance itself. Inverter welding machines, refrigerators, air conditioners, especially inverter ones, washing machines, microwave ovens with a regular household plug do not require the installation of a machine with characteristic C.
If the voltage in the network drops below 198 volts, then machines with characteristic C should not be installed.