Design load, online calculator, converter

What are the dangers of exceeding the permitted power?

Currently, when it detects that the maximum load has been exceeded, the electric company introduces a consumption limitation mode. The basis for this is a violation of the obligations specified in the energy supply agreement. As a rule, limiting consumption is turning off the electric current. The algorithm for sending such a notification is shown in the figure.

Example of a consumer notice

After 10 days after sending the notice, the company disconnects the power supply. To avoid this, the consumer must eliminate the violation within ten days, and then contact the service provider to draw up the appropriate report. Electricity supply will be restored after the electric company pays the penalty in accordance with the contract.

More serious consequences may arise if, in addition to violating the amount of allocated energy, an accusation of uncontrolled electricity consumption is brought forward. The basis for this will be the removal of seals from the input machine. You can get more detailed information about the consequences of uncontrolled electricity consumption, electricity metering rules, etc. on our website.

Seal on the introductory machine (marked in red)

Design power for industrial facilities

The design capacity of an industrial enterprise depends on:

type of product;
technologies used;
expected maximum load during the year;
type of products;
type of equipment and the degree of its adaptation to technology.

There are many calculation methods, all of them must have common properties:

ease of calculation;
versatility in determining loads for different levels of energy consumption and distribution;
accuracy of results;
ease of determining the indicators on which the method is based.

The main indicators are calculated using the same formulas, but with different correction factors.

For three-phase electric motors, the installed power is:

Р = Рн/(η x cos φ), where:

Рн – nominal power indicator from the data sheet;
η – efficiency of the electric motor;
cos φ – power coefficient.

An increase in the allocated power, according to technical conditions, must be agreed upon with the energy supply organization. For this purpose, recalculations are carried out for input cables and protection devices based on the new installed power. But the decision to allocate depends on the availability of free capacity.

What it is

During capital construction during the USSR, for example in Khrushchev buildings, i.e. In most of the residential premises that are still in use today, even at the design stage, the allocated power was 1.5 kW per apartment. Later, the established electricity rate increased to 3 kW, as it became necessary to increase it due to the increased “gluttony” of consumers. Practice shows that 10-16 Ampere plugs were usually installed in electrical panels and meters, so that the maximum current consumed by an apartment was limited to a total electrical power of 3 kW for apartments with a gas stove. For apartments where an electric stove is installed, 7 kW is allocated. In new buildings, the allocated power can reach up to 15 kW. This scatter is due to the fact that during the construction of old houses (60s, 70s) there simply were not such powerful consumers and as many household appliances as there are now.

The allocated power is the maximum amount of electricity consumed at one point in time.

In addition, in order to enter the established limit, sometimes you need to enter not just 1 phase, as often happens, but as many as 3 phases. This is necessary for connecting modern household appliances, such as powerful electric boilers and electric stoves. This is especially true in commercial premises and industries of any scale, where a lot of electricity is needed (up to 30 kW and above).

Example

. To heat a country house that is not equipped with gas equipment, solid fuel and electric boilers are installed, the latter are safer and more convenient. For heating a house with an area of 100 sq.m. you need a boiler with a power of about 7-10 kW, an electric stove consumes another 3-5 kW. In total, it is necessary to increase the established electricity limit to a minimum of 15 kW and supply electricity in three phases.

To find out the allocated power for a private house or apartment, you need to contact the operating organization (in Moscow and the region - this is Mosenergosbyt OJSC). The help contains information about the allocated and average power consumption. It will be needed if you are preparing documents for an increase; this will be discussed in detail below.

Rules and regulations

Seal on the introductory machine

Electrification of residential, administrative, and industrial facilities is carried out on the basis of the specifications of the provider organization. One of the clauses of the contract specifies how much power will be allocated to the consumer network. The basis for declaring power and forming technical specifications are calculations.

Electrical connection to residential and public buildings is carried out in accordance with SP 31-110-2003 and temporary instructions RM 2696-01. The documents state that the allocated electrical power for houses that consume electricity of the 1st category is not standardized. Objects are connected based on requests.

Housing stock of the 2nd category has two electrification standards:

from 5 to 7 kilowatts is the norm for a private house or apartment where gas stoves are installed;
from 8 to 11 kW - for objects where there is an electric stove.

The least amount of power falls on a small-sized apartment and a house built under the social housing program.

Currently, the standards from 2006 are in effect. In buildings before this period, the power output is much lower.

Estimated power of residential buildings

The installed power in a residential building is determined based on the sum of the consumer rated powers of all electrical appliances and installations, and the calculated power - taking into account the expected simultaneous switching factor.

Each subscriber has a delineation act, which records the installed and calculated power. These values are different for houses and apartments. Houses and some apartments are usually supplied with three phases, which allows increasing the consumption (calculated) indicator. Single-phase input significantly limits consumption. The load is controlled by protective equipment designed to handle the maximum possible currents.

If there is no power plant in the house or apartment, the calculated energy is determined by the formula:

P1 = Pmax + M x Rchel, where:

Pmax is the power of the largest receiver installed in the apartment,
M – number of inhabitants,
Rchel – estimated power per person (for example, 1 kW);

Important! This formula does not take into account heating of residential premises

The estimated power of the power supply cable for an apartment building is made taking into account the number of apartments:

Р = Р1 x nxk + Ra + Рл, where:

n – number of apartments,
k – simultaneity coefficient (it ranges from 0.6 to 0.8),
Ra – installed power of administrative electrical receivers,
RL – elevators.

If there is no data, then Pa is taken equal to 0.5 kW, Rl = 20 kW.

With electric heating, Po = P + K1 x ΣRkv, where:

P – design power without electric heating,
K1 – coefficient of simultaneity of heat load in n apartments,
Rkv – heating energy in one apartment, kW.

Important! Accurate determination of the estimated power required for space heating requires detailed calculations, which are carried out jointly with builders and building designers. In residential buildings with predominant heating elements cos φ = 1

The calculated power indicator for a group of buildings is determined by the empirical formula:

Рз = 0.95 x kx ΣР, where Р is energy for one building.

Install the PZR corresponding to the permitted power

If the permitted power

is limited or the home is oversaturated with electrical receivers - household electrical appliances, electronics, lighting devices - and there is a possibility of power consumption exceeding its value, then instead of the input circuit breaker it is necessary to install a
PZR
(protective relay device), consisting of an electronic unit, a current relay, a magnetic starter and circuit breaker.

When the load current of the internal network reaches a threshold value corresponding to the permitted power

, the current relay is triggered and switches the internal network to periodic power supply mode: the network is connected to voltage for 5 seconds, then a pause of 180 seconds follows, during which there is no voltage in the network.

This mode lasts until the subscriber takes measures to reduce current consumption.

PZR

multifunctional. In addition to limiting the load current, it protects the internal network from short circuit currents, insulation leakage currents, and overvoltage.

Calculation of required power

This calculation will be needed to understand whether the amount of allocated electrical power for an apartment or house will be sufficient. To do this, you will need to calculate the maximum load by summing up the corresponding parameters of all consumer electrical installations. Moreover, it is necessary to take into account all household electrical appliances that can be turned on at the same time.

As a rule, all the necessary information is indicated on a sticker affixed to the equipment body or is given in the documentation. If the sticker has become unreadable and the technical data sheet has been lost, you can use the table that shows the typical active power of household equipment.

Table of approximate power consumption of various household appliances

Having calculated the total consumption, do not rush to consider the work completed; it is necessary to add a reserve, taking into account a possible increase in load over time. As a rule, the size of the reserve is set at 20-30% of the calculated parameters.

By adding these two values, we get a result that can be compared with the allowed power. If it turns out to be less than the calculated load, it makes sense to think about applying for an additional 1 kW or 3 kW. Details about adding additional kilowatts will be discussed below.

Calculation of maximum input power

Electrical load is understood as the amount of electric current flowing in the network when an electrical receiver or group of electrical receivers is turned on.

Based on electrical loads, conductors are selected (design, cross-section) at all stages of generation, conversion, transmission and consumer use of electrical energy and its distribution. There are 3 methods for determining the electrical loads of objects:

1 Method for constructing a daily graph of electrical loads;

2 Method of ordered diagrams or method of effective number of electrical receivers;

3 Analytical method

To calculate the load at the entrance to the dairy block building, the method of constructing a daily graph of electrical loads is used. Since it is possible to install a clear time cycle of technological equipment at the facility.

To construct a load graph, auxiliary table No. 7 is compiled.

Table No. 7. - Auxiliary table for constructing a load graph.

Technological operation	power, kWt	Operation duration
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24
1 Milk pump	2,2
2 Vacuum - pump	8
3 Cooler	18,74
4 Separator	2,2
5 Heater	12
6 Lighting	1,74

A daily load schedule is drawn up (Figure 1).

Figure 1 - Graph of electrical loads.

The graph shows that the maximum active power is:

The installed power is determined by summing up all the loads present at the facility:

, (32)

where is the power of the i-th load, kW.

Electricity consumption per day is determined through the geometric area of the graph:

(33)

Average power consumption per day:

(34)

The average value of the power factor of the loads involved in the formation of the maximum load:

(35)

The total power at the input is determined:

(36)

Input current at maximum load:

(37)

Based on the operating current, we determine the cross-section of the input cable based on the conditions.

Iadd? Iр, (38)

Iadd = 65A? Iр = 52.65A.

We accept for installation a cable at the AVBBShv 5*25 input.

Document overview

The Procedure for forming a consolidated forecast balance of production and supply of electricity (capacity) within the Unified Energy System of Russia by region has been re-approved.

The objectives of creating a balance are to satisfy the demand for electricity and power, minimize the costs of their production and supply, ensure reliable energy supply, as well as balance the total cost of electricity and power supplied to the wholesale market at regulated prices (tariffs) and sold under regulated sales contracts (supplies) in price and non-price zones.

Balance is needed to achieve 3 goals. The first is the calculation of regulated prices (tariffs) for electricity and power, subject to state regulation, as well as regulated prices (tariffs) for services provided in the wholesale and retail markets. The second is the conclusion by participants of the wholesale market of agreements, on the basis of which the purchase and sale of electricity and (or) capacity is carried out on such a market. The third is the conclusion by producers (suppliers) of purchase and sale (supply) agreements for electricity and capacity with a supplier of last resort in regions united in non-price zones. We are talking about manufacturers (suppliers) who are subject to the legal requirement to sell produced electricity (power) only on the wholesale market and who, before receiving the status of a wholesale market entity, participate in purchase and sale relations on the retail market.

The Procedure for determining the ratio of the total annual forecast volume of electricity consumption by the population and equivalent categories of consumers to the volume of electricity corresponding to the annual average value of the forecast capacity determined in relation to these categories of consumers was also approved.

The ratio is established to determine the planned volumes of consumption by the population for the next regulated period based on the results of control measurements. They are carried out by guaranteeing suppliers, energy supply and sales organizations that supply electricity (power) to the population and equivalent categories of consumers in the year preceding the next regulated period.

The order approving the previous procedure for the formation of a consolidated forecast balance was declared invalid.

To view the current text of the document and obtain complete information about the entry into force, changes and procedure for applying the document, use the search in the Internet version of the GARANT system:

What is dedicated electrical power

If we explain the meaning of this term in simple language, then the allocated (or permitted) power is the maximum permissible load on the consumer’s network. It is established in accordance with current standards and is indicated in the electricity supply contract.

Those who want to understand this issue in detail should have an idea of connected, installed, one-time and permitted capacity. Let's give a brief definition of each of them:

Connected, this term means the total installed power of all electrical receivers powered from the consumer's network.
Installed - rated active power specified in the technical documentation for electrical equipment, that is, that at which consumer devices will operate in normal mode.
One-time – the estimated amount of power consumption of electrical installation equipment for a certain time.
Allocated (allowed) – the maximum one-time power that a consumer can connect to the energy supply company’s network. This parameter is indicated in the specifications for connecting energy-receiving facilities and in the agreement between the consumer and the organization supplying electricity.

Apply priority relay

In conditions where the installed power

household electrical receivers significantly exceed
the permitted power
and the probability of tripping
sectional circuit breakers
increases,
priority relays are used.
This is an electric current relay, the input terminals of which are connected to the supply voltage, and the output terminals are connected to separate sections of the internal electrical network that have different priorities. For example, a section of sockets and a section of electric floor heating. The socket section is given higher priority than the underfloor heating section.

Priority relay

a mode is set in which the total load current in the connected sections reaches a certain value, it is triggered and turns off one or more sections with a lower priority.

After some set time, the relay loses power and sections with lower priority are automatically connected to the power supply. If the nature of the load has not changed, the relay is activated again.

Installed capacity for power plants

For power plants, the installed power is calculated by summing the power ratings of the individual generators and their associated motors. Almost always these values are identical. In cases of discrepancy, the calculation is carried out using a lower power.

As a result, at expensive stations with high fuel economy, the cost of electricity is extremely dependent on the consumption mode. Therefore, for large stations it is beneficial to use the installed capacity for a maximum of hours per year, and for small gas turbine plants with high fuel consumption, it is more expedient to switch them on during peak load hours, when the total operating time on an annual basis is small.

How to find out how much power is allocated

Those who do not know the amount of permitted power for a house or apartment can use the following ways to obtain information:

Get a certificate from the energy supply company. It should be taken into account that such a service is considered paid; for example, at Mosenergosbyt you will have to pay from 1.3 to 3.1 thousand rubles for it, depending on the category of the residential property.
Look for the required parameter in the energy supply contract or technical specifications.
Obtain information empirically by looking at the parameters of the input protective device. The fact is that in most cases, in addition to its direct functions, it plays the role of a power limiter. To set its maximum value, it is enough to find out the operating current of the machine.

Operating current parameters (marked in red)
The figure shows a diffautomatic machine with an operating current of 32 A (Inom). Therefore, the maximum permissible load power can be calculated using the formula: Pmax = U x Inom x 0.8; where U is the rated network voltage. Therefore, 230 x 32 x 0.8 ≈ 5.5 kW.

Of all the options presented, the most reliable is the first, especially since a certificate will still be needed if you plan to increase the allocated power (it is included in the package of necessary documents).

Calculations based on the operating current of the input circuit breaker should not be trusted too much. Some models of modern electronic meters have a built-in load relay. In such cases, the rated current of the machine may be overestimated.

Install sectional circuit breakers that provide current selectivity protection

In order not to lead to the disconnection of the entire facility from the power supply due to an overload of a particular section, for example, a section of sockets when several sufficiently powerful electrical receivers are turned on at the same time, sectional circuit breakers

They are installed after the PZR

and protect the section circuits from short circuit currents and overloads.
Each sectional circuit breaker protects one specific section. The current settings of the thermal relays built into them are selected in such a way that if any section is overloaded, the sectional machine protecting it will turn off earlier, without leading to the operation of the PZR.
Protection by sectional circuit breakers

effective, but not very convenient.

Firstly, the load in several sections may not reach the maximum value at which the sectional machine would operate, but in total it may be large enough for the PZR to operate.

Secondly, to restore the protective functions of a triggered machine, you need to manually transfer it from non-working to working state - the lever from position “0” (or “off”) to position “1” (or “on”).

Clock for calculating the actual power value in the retail market

How to measure power consumption and check the meter How to measure power consumption and check the meter Knowing the power is required in many cases. For example: To calculate the required cross-sections of the electrical wiring cable. To determine electricity consumption, power consumption. Let's take a closer look at power consumption. Nowadays there are a lot of household appliances. The approximate operating time in hours and monthly electricity consumption are indicated. Of course, the data is averaged, you can create a similar table for your equipment. Calculate using new data. How can you measure power at home? The most common method is using an electricity meter.

DESIGN AND PRINCIPLE OF OPERATION OF EPU

Uninterrupted power supply of stationary communication equipment requires direct current electrical energy with rated voltages of 24, 48 and 60 V. This energy is provided by power supply units produced by various domestic and foreign companies. One of them is the German company Voigt&Haeffner (V&H), which produces units for various capacities.

The work presents a medium-power electronic control unit of the SVS-G48/75-8GRS type with a rated voltage of 48 V and a rated current of 75 A. It is developed on the basis of a modular architecture that allows you to increase the power and develop the operational capabilities of the installation. The equipment is located in two cabinets. In the top are the main elements of the installation, in the bottom are the batteries. The placement of installation elements is shown in Fig. 1.

Main EPU devices and their designations:

Rice. 1. Placement of elements

The block diagram of the installation is shown in Fig.

Conditions for transferring maximum power from the energy source to the receiver

Overhead Line > AC Circuits. Theory.

Conditions for transferring maximum power from an energy source to a receiver Let's imagine an energy source with EMF E and internal resistance by an equivalent circuit (Fig. 3.22). Let's find out what the resistance Z=r + jx of the receiver should be so that the active power transmitted to it is maximum. Receiver power Obviously, for any r, the power reaches its greatest value at . In this case, taking the derivative with respect to r from the resulting expression and equating it to zero, we find that P has the greatest value at . Thus, the receiver receives the greatest active power from the source if its complex resistance is conjugate with the complex internal resistance of the source: Under this condition and efficiency In electric power plants, the maximum power transmission mode is unprofitable due to significant energy losses. In various types of automation, electronics and communications devices, the signal powers are very low, so it is often necessary to specially create conditions for transmitting the maximum possible power to the receiver. A decrease in efficiency often does not matter at all, since the transmitted energy is small. Matching the resistances of the receiver and the power source in accordance with (3.50) can also be achieved by adding elements with reactance to the circuit (see example 4.6). Sometimes the resistance of the receiver can be changed without arbitrarily, but only with maintaining the relationship between active and reactance, i.e. at . An analysis, which is not given here, shows that in this case the power P is maximum if the impedances of the receiver and the source () are equal to each other, while matching the impedances of the receiver and the power source can be achieved by turning on the receiver through a transformer. In the general case of a receiver - a branched passive circuit - Z is its input impedance.

Use latching relays

Locking relay

(a current relay is used as a blocking relay) makes it impossible to simultaneously turn on two sections or separate high-power electrical receivers, depending on the connection point of the relay coil and its opening contact.

The section or that receiver (No. 1) is turned on, in the circuit of which the relay coil is installed, and the section or that receiver (No. 2), in the circuit of which its opening contact is located, is turned off.

If the blocking relay

has an adjustable setting, then the section or receiver No. 2 is switched off when the current in the section or receiver No. 1 reaches the specified value. Section or receiver No. 2 is connected to voltage when the current in section or receiver No. 1 decreases to the set value multiplied by the relay return coefficient, without a time delay.

When using one relay, the effect is similar to that which occurs when using a priority relay: the section or electrical receiver in whose circuit the relay coil is connected will have a higher priority.

If you install blocking relays in both sections or in the power circuit of two receivers in a cross circuit, then the one that was turned on first will remain working.