Choice ab. Car battery: chosen by the expert “Behind the wheel. Why do car batteries produce the declared current for such a short time when tested?

The most preferred types of rechargeable batteries (AB) for use at energy facilities are lead-acid batteries closed type with liquid electrolyte.

Overview of battery types

Depending on the design of the positive electrode, the following types of batteries are distinguished:
OGi, OSP, VARTA BLOCK - with a spreadable positive electrode.
This type of battery has the most wide application in the designs of stationary lead batteries.
A rod lattice plate made of lead alloy with low antimony content is used as a positive electrode (current conductor).
Electrode paste is placed in the grid, which is obtained by mixing lead powder and sulfuric acid.
With rock battery life of this type is 15-20 years.
They are used for mixed types of loads - cyclic and jolting.

OpzS, OCSM - with armored (tubular) positive electrode.
The electrode is made in the form of a rod with branches.
A perforated cover made of acid-resistant dielectric, which is filled with active mass (electrode paste) of the positive electrode, is put on the rod.
The cover ensures contact of the active mass with the current conductor and prevents its removal from the surface of the electrode.
The service life of this type of battery is 20 years.
P are used for cyclic loads

GroE – with surface positive electrode (PLANTE).
And have the lowest internal resistance of all the types considered.
And x electrodes are made of refined lead and are a lamella with a very high effective surface area.
The low internal resistance of GroE batteries determines a stable level of discharge voltage, especially at high load currents.
The service life of batteries of this type is 25 years.
P are used when high level shock loads.

The negative electrodes of all batteries are made using spreadable technology.

At less critical facilities, lead-acid batteries of the sealed type are often used according to the technology type AGM, they are also called maintenance-free batteries.

AGM type technology - batteries with liquid electrolyte absorbed into a fiberglass separator.
Since the separator is not completely saturated with the solution, the free volume is used for recombination of gases, so the battery does not require topping up water during its service life.
Positive and negative plates AGM batteries- namazny type.

System loads direct current energy facilities

DC system loads can be divided into the following types:

- corresponds to the current consumed from the buses of the DC system in normal mode and remains unchanged throughout emergency mode.
In normal mode, the constant load is taken over by chargers.
The constant load includes control, blocking, alarm and relay protection devices, and a constantly switched-on part of the emergency lighting.

- corresponds to the current of consumers connected to the battery when the alternating current and characterizes the established emergency mode;
The temporary load includes emergency lighting, electric motors of emergency oil pumps of the lubrication system, sealing and regulation, and a communication converter unit.

- lasting several seconds, it is characterized by consumption from battery current in transient emergency mode.
Short-term loads include starting electric motors, turning on and off switch drives.

The duration of the emergency mode (disappearance of alternating current) is taken according to the design specifications.

If not present in the task, it is assumed to be equal to:
- for thermal power plants included in the system- 30 min;
- for isolated power plants- 1 hour;
-for electrical substations- 2 hours.

Calculation and selection of batteries for power plants

As a rule, several batteries are installed in power plants.

The quantity depends on the power of the turbine units and the type of thermal circuit.

At CHP plants with cross-connections in the thermal part with a power of up to 200 MW, one battery is installed, and with a power of more than 200 MW - two of the same capacity.

At CHP plants with block thermal power supply circuits, for each of the two blocks serviced from one block panel, installation, as a rule, of one battery is provided.

For units with a capacity of 300 MW and above, in cases where the use of one battery for two units is impossible due to the conditions for choosing DC switching equipment, it is allowed to install a separate battery for each unit.

As an example, let’s consider the choice of a battery for a block heat and power plant with units with a capacity of 300 MW.

We perform calculations for the AB of one of the CHP units.

And similar data on DC system loads in emergency mode: - 50A;
-converter communication unit No. 1- 35A, starting current - 175A;
-converter communication unit No. 2- 25A, starting current - 150A;
-emergency lighting- 100A;
- seal system oil pump No. 1- 30A, starting current - 90A;
- seal system oil pump No. 2- 115A, starting current - 345A;
-lubrication system oil pump No. 1- 65A, starting current - 195A;
-lubrication system oil pump No. 2- 65A, starting current - 195A;
- starting current 400A.

-discharge time - 30 min;
- 485A;
-maximum peak current- 400A;
- 885A.

The voltage on the busbars of the DC switchboard (DCB) during operation should be maintained 5% higher than the rated voltage, i.e. 220*0.05+220=231V.

Typically, power plants accept 1-2 more elements, i.e. 105-106 elements.

This increase is required to compensate for the voltage drop in cable lines and taking into account the need to maintain the standard voltage level for loads, especially with high inrush currents.
The final number of elements is determined by calculations of the voltage drop in the DC network.

Application of element switch

Element switch is a device for continuous switching of battery elements in emergency mode to maintain the required voltage level on the power supply buses, and in the battery recharging mode.
In emergency mode, when the battery is gradually discharged and the voltage decreases, the number of elements is added by switching the discharge brush towards increasing the number of connected elements.
In the additional charging mode, when it is necessary to apply increased voltage to each battery cell, the number of battery cells is switched downward using the charging brush to maintain the power supply on the busbars given level voltage.
When using an elemental switch, the total number of elements is usually taken to be 130, so that at the end of the emergency mode, with a voltage on the battery element equal to 1.8 V/el, the voltage on the battery is 1.8x130 = 234V.

Application of DC voltage stabilization device

A device of this type, for example UTSP, is a transistor converter DC voltage to a constantly elevated level.
In emergency mode, when the battery is gradually discharged, the voltage at the device output is maintained constant at the set level.

The battery capacity is selected in the following order:

1. The steady current at the end of the emergency mode is determined taking into account the reduction in battery capacity according to the expression

Ist1 = Ist/(0.8xKt);

g de Iust, A - steady current of emergency mode;
0.8 - battery capacity coefficient (at the end of its service life the capacity will be 80%);
K t - temperature coefficient depending on the minimum possible temperature in the room.

For our example, we obtain Iset1 = 485/(0.8x1) = 606.3 A.

2. The equivalent load time is determined taking into account the current surge at the end of the emergency mode according to the expression

T 1=(Iust1xTavar)/It1;

g de Tavar, min - duration of emergency mode;

I t1=It/0.8 A - maximum inrush current at the end of the emergency mode, taking into account the established one and taking into account the decrease in battery capacity towards the end of its service life;
g de It, A - maximum inrush current at the end of the emergency mode, taking into account the established one;
0.8 - battery capacity coefficient;

E equivalent time T1=(606.3x30)/1106.3=16.4 min;

I t1=It/0.8 A=885/0.8=1106.3A

Next, you need to take the discharge characteristics of pre-selected types of batteries and see what capacity the battery needs to be taken so that it can withstand a current of 1106.3 A for 16.4 minutes at a voltage of 1.8 V/cell.
For example, these are 13 GROE 1300 or 22 OGI 1600 LA batteries.

Calculation and selection of battery for substations

Substations usually have one or two batteries installed.
D For substations with higher voltage 220-750 kV and substation 110 kV with more than three circuit breakers in the switchgear high voltage two batteries are installed.
For substations with a voltage of 35 kV and substations with a voltage of 110 kV with three or less circuit breakers, one battery is installed in the high voltage switchgear.
Each battery is selected taking into account the full DC load at the substation.
As an example, let’s consider the choice of battery for a 110 kV substation.

And similar data on DC system loads in emergency mode: - 10A;
-emergency lighting- 20A;
- switch drive outdoor switchgear-110 kV- starting current 100A.

Let's leave the emergency schedule

And the sales indicators of the emergency mode schedule:
-discharge time - 180 min;
- steady-state emergency discharge current- 30A;
-maximum peak current- 100A;
-maximum peak current taking into account steady-state- 130A.

Selecting the number of battery cells

The voltage on the switchboard buses in operating mode is 5% higher than the nominal - 231V.
Charging mode 2.23V/cell - 231/2.23 = 104 cells.
Next, you need to calculate the voltage drop in the DC network and, if necessary, add 1-2 elements.
If the voltage level turns out to be insufficient, then you should use a circuit that separates the power buses (PS) and control buses (CC).
In this case, the switch drives are connected to the ShP buses, which are connected to the entire battery, and the remaining loads are connected to the ShU buses, which are connected to 104 battery elements.
Recently, there has been a tendency to reduce the starting currents of switch drives, therefore, when designing new substations, it is sufficient to use a battery consisting of 104 elements.

Selecting battery capacity

The procedure for selecting battery capacity is exactly the same as for power plants.

1. Determine the steady current at the end of the emergency mode, taking into account the reduction in battery capacity

I mouth1 = 30/(0.8x1)=37.5 A;

2. Determine the equivalent load time taking into account the current surge at the end of the emergency mode

T 1=(37.5x180)/162.5=41.5 min;

I t1=It/0.8 A=130/0.8=162.5A

A peak current of 162.5A for 41.5 minutes at a voltage of 1.8 V/el can be produced by a 11GROE275 or 5OGI325 LA battery.

When selecting a battery to create a partition power supply project power facilities, it is important to take into account the relevance of data on the discharge characteristics of batteries.

X characteristics are updated quite often, so before you start calculating and selecting a battery, contact the manufacturer for the current discharge characteristics of the battery.

P.S. Copying article materials is possible only if there is an active link to the source!!!

Produced in accordance with the DC load schedule. Figure 13.1 shows a graph of DC load for 3x63 MW. This graph shows the following values:

I1 - permanently switched on load (control, blocking, alarm and relay protection devices, permanently switched on part of the emergency lighting);
. I2 - current consumed by electromagnetic drives of 6 kV switches;
. I3 - backup converter unit of communication devices;
. I4 - emergency lighting;
. I5start - starting engines emergency oil pumps (AMP) generator shaft seals;

I5 - working engine AMN generator shaft seals;. I6start - starting the AMN engines to lubricate the turbine bearings;
. I6 - worker of AMN engines for lubrication of turbine bearings;
. I7 - current consumed by the electromagnetic drives of the 220 kV circuit breaker;
. Ist - steady (half-hour) emergency mode;
. Imax - maximum jolt at the end of the discharge.

Domestic power plants usually use SK type batteries (stationary for short-term discharge), produced in 46 standard versions with a capacity of 18...5328 Ah. The characteristics of SK-1 batteries are presented in Table 13.1.

The discharge currents and capacities of other batteries (SK-2, SK-3, ..., SK-46) are determined by multiplying the corresponding value for SK-1 by the type number. For example, the SK-14 battery has a one-hour discharge capacity of 14·18.5 = 259 A. The steady-state value of a fully charged SK battery with an open circuit is 2.05 V.
For thermal power plants, a battery circuit with an elemental switch operating in constant recharge mode has been adopted.
The number of elements connected to the buses in the constant recharge mode is determined by the formula:

where Iset is the load of a steady-state (half-hour) emergency discharge, A;
1.05 - safety factor;
j- permissible load emergency discharge, A/N, reduced to the first battery number, depending on the electrolyte temperature (Fig. 13.2).
The resulting number is rounded to the next higher standard number.

determined by the curve corresponding to the temperature of the batteries, the deviation on the batteries as a percentage (Fig. 13.3). The found value is compared with acceptable values deviations according to Table 13.2, taking into account the drop in connecting cables

Let us demonstrate the application of the described methodology using the example of choosing a battery for 3x63 MW. The calculation of the battery load is summarized in Table 13.3, the load graph is shown in Fig. 13.1. Table 13.3 does not contain I2 consumption electromagnetic drives switches 6 kV, because this load occurs at the beginning of the discharge and disappears completely after operation

the specified switches.

Sources uninterruptible power supply are a guarantee of the operation of any household appliance, despite a possible power outage. Therefore, UPS are in great demand, especially in rural areas, where power outages have long become the norm. The most important element Emergency power systems are batteries for UPS.

As experts say, batteries are good and bad, but this is a rather subjective assessment. What parameters can actually be indicators of quality?

Here are some of them:

First of all, the number of charge-discharge cycles is assessed. The battery life, and therefore the operation, depends on this;
The next quality indicator is loss of charge or self-discharge. Some types of batteries can hold a charge for a long time, and some discharge quite quickly;
When choosing a battery, you should also pay attention to the temperature range at which the manufacturer guarantees the functionality of the product without deteriorating its characteristics.

Selecting a battery for a UPS

The battery for uninterruptible power supply is selected according to electrical characteristics and designs. Electrical parameters practically do not depend on the design of the product and are the same for different types rechargeable batteries.

The main electrical characteristics include the following parameters:

Battery capacity in A/h;
Rated voltage;
Number of charge-discharge cycles;
Maximum depth of discharge;
Self-discharge;
Internal resistance;
Charging current;
Working temperature.

How to determine the required capacity?

One of the main parameters by which a battery is selected is its capacity. The time during which Appliances will be provided electrical energy in case of main network outage. The unit A/h (ampere/hour) is used to indicate the battery capacity. It indicates how much current will be supplied to the load per unit time.

So, a battery with a capacity of 50 A/h can provide a current of 50 amperes for one hour or 5 amperes for 10 hours. The most widely used batteries are those with a capacity of 50 to 200 A/h.

To determine the uninterruptible power supply time, you should use a simple formula:

Q=(P*t)/V*k

Where:

Q – battery capacity;
P – known load power in watts;
t – required reservation time;
V – rated battery voltage;
K – capacity utilization factor.

Example: there is an active load of 140 W, which must operate without interruption when the voltage is turned off, for 5 hours. The battery supply voltage is 12 V, and the capacity utilization factor is usually 0.6-0.8.

Substitute the values into the formula:

(140*5)/12*0.7=83.3 A/h

We find that the battery capacity to provide voltage to this load for 5 hours should be 83.3 A/h. Thus, we select the battery with the closest nominal value of 100 A/h.

Other selection criteria

Voltage and number of cycles. The battery for an uninterruptible power supply can have a standard voltage corresponding to 12, 24 or 48 volts. The number of charge-discharge cycles is, as a rule, the service life of a particular battery.

Their number can vary from 200 to 1000, depending on the battery design. In this case, the maximum permissible full discharge is taken into account. If the battery is discharged to some intermediate value, then the number of cycles increases noticeably.

Discharge depth. Any battery has important parameter- this is the maximum permissible depth discharge. Not a single battery allows a complete, so-called zero, discharge without damage to its design. The battery passport always indicates the permissible and recommended discharge level.

Some models are very critical to the depth of discharge. Exceeding this value for acid batteries with lead electrodes can lead to full exit products out of order. Modern nickel-cadmium batteries are less susceptible to this defect.

Self-discharge. The battery for the UPS, which is installed in, is not subject to self-discharge, since it is always connected to charger. The concept of self-discharge refers to the loss of part of the battery charge as a result of long-term storage.

Lead acid batteries can lose up to 50% of their capacity when stored under normal conditions (+20°C) for a year. It is very important when choosing and purchasing a battery to pay attention to the manufacturing date. If the battery was manufactured 3-4 years ago and was stored in a warehouse all this time, it is not worth purchasing it.

Such a parameter as the internal resistance of the battery is sometimes mentioned in technical articles, but detailed information there is little information about this parameter. This value may or may not be indicated in the documentation for the battery. The internal resistance of a battery is the total resistance of the electrolyte, plates, contacts and everything else. This parameter is not a constant value and may change during battery discharge. It is impossible to influence this parameter, so when choosing a battery for a backup power source, it is best not to pay attention to it. The only criterion here can be only one - the lower the internal resistance of the battery, the better, since less energy will be spent on internal losses.

Charge current. The battery charge current is indicated in the documentation for the backup power source. Typically, the charging current should be approximately 10% of the battery capacity. A current of 5 amperes is suitable for charging 50 A/h batteries, but they can charge batteries up to 100 A/h. Since 100 A/h batteries are used most often in backup power supplies, the optimal charging current there will be a current of 10 amperes.

Operating temperature. The operating temperature can be very important for the battery power supply. It has a particularly negative impact on work elevated temperature. When working in difficult conditions The battery discharges much faster, and its service life is noticeably reduced. Full time job at temperatures elevated to +30°C it can reduce battery life by 25-30%.

Uninterruptible power supply devices have space for installation standard battery, but some UPSs allow the connection of additional batteries to increase operating life external devices when the main network is disconnected.

Types of batteries

UPS batteries can be the most different designs. Some have been known for several decades, some were developed relatively recently, but have already gained great popularity due to their high technical characteristics.

Batteries can be divided into several groups:

Batteries with acid electrolyte and lead electrodes;
Batteries with gel electrolyte;
AGM batteries;
Ni-Cd batteries;
Li-ion, Li-PO batteries.

Batteries with liquid electrolyte

They are an unsealed container with lead electrodes. A solution of sulfuric acid is used as an electrolyte. Batteries emit hydrogen and sulfuric acid fumes, which limits their use in domestic premises.

Such batteries can be used as additional batteries if they can be placed in separate ventilated rooms. The batteries are characterized by low cost, reliability and a large number of charge-discharge cycles

Gel batteries

This design is further development acid batteries. Thanks to the addition of a silicon-based thickener, the liquid electrolyte turns into a jelly-like mass. Gel batteries for UPS are completely sealed, do not emit toxic substances and are very reliable. They have a large capacity and a large number of discharge-charge cycles. GEL batteries are very critical to deep discharge, and are more expensive than batteries with liquid electrolyte.

Batteries with AGM technology

The result of further modernization gel batteries was the emergence of AGM power supplies. They are considered modern and promising models. In these batteries, the liquid component is absorbed by a special porous material. The batteries can be used in any position. They have very little internal resistance.

AGM batteries for UPS are characterized by high capacity, reliability and long service life. Such sources are most often used in backup power supplies.

Nickel-cadmium batteries

These types of batteries are characterized by a large number of charging cycles and high specific capacity. They have low self-discharge and can be used in wide range temperatures These batteries are compact and have low self-discharge.

Their use is limited by the high price and the use of cadmium compounds in the design, which are very toxic, which complicates not only their operation, but also their disposal.

Batteries with Li-electrodes

Lithium-ion and lithium-polymer batteries, with development innovative technologies are becoming more widespread. These batteries are compact sizes have large capacity and can provide energy to a high-power consumer.

Lithium batteries do not lose capacity during operation and have very low self-discharge. The disadvantages are their high price and a small operating temperature range.

Battery from the company "Energy"

Famous Russian company"Energy" producing electrical devices and systems, produces both backup power supplies and batteries for them. A 12 volt UPS battery with a capacity of 100 A/h can be considered the most popular.

The Energy 12-100 battery is made using the most modern AGM technology. It allows a large number of discharge-charge cycles, has minimal self-discharge and is designed for a 12-year service life.

The battery for a 12V UPS will last a long time subject to elementary rules operation: