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– the number of discrete outputs to indicate overloads in power circuits of the device – one;

– the number of switched phases – three;

– reversible phases – B and C.

2.2. Arranged on the device front panel are the OPERATION (green- Сcolor) and OVERLOAD (red-color) light-emitting diodes, the RESET button, as well as the CONTROL, 380 V INPUT and 380 V OUTPUT termi-

nal connectors.

2.3. Electrical parameters and characteristics

и2.3.3. Starting time – not more than 10 s.

2.3.1. The device derives the supply from an external DC power

source of (24±0.24) V.

2.3.2. Power consumption of the device via the +24 V circuit is not

more than 180 mA.

2.3.4. As to its level of protection from electric shock, the device belongs to protection class I in compliance with the requirements of GOST 12.2.007.0.

2.3.5. The insulation voltage across the power circuits, control cir-

cuits and the +24 V circuit of the device withstands a test voltage of 1500 VAC 50 Hz without breakdown and surface flashover in normal climatic conditions.

2.3.6. Insulation resistance of the power circuits relative to the con-

trol circuits and the +24 V circuit is not less than 20 megohms in normal climatic conditions.

бА

2.4. The device is rated for continuous operation.

2.5. The parameters of the device discrete inputs are as follows:

Д

–open (closed) contacts of a system connected to the device correspond to the logical zero (unit) at the "Open", "Close" inputs;

–the logicalzero voltage at the "Interlock"input is equal from 0 to 1V;

–the open state of contacts of the system connected to the device corresponds to the logical unit at the "Interlock" input;И

– the minimum duration of the logical unit or zero is equal to 0.1 s;

– the current value in the "Open", "Close" and "Interlock" circuits ranges from 15 to 24 mA.

2.6. The limit parameters of the device keys are as follows:

–a root-mean-square value of the power key switching voltage is not more than 420 V 50 Hz;

–an amplitude value of the power key switching current is not more than 10 A;

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–the overload key switching voltage is not more than ±36 V;

–the overload key switching current is not more than 0.5 A.

2.7.The device ensures protection against overloads and short circuits in phases B and C.

2.8.The electrical drive supply circuit protection actuating current value is equal to (10±1.5) A.

2.9.Reliability

2.9.1.Mean-cycles-between-failures of the device are not less than

40,000 h.

2.9.2.Service life of the device makes up 10 years.С

и3. Overall Dimensions and Mass

3.1. Overall dimensions of the device are given in Figure V.2.1. 3.2. The device mass is not more than 1.8 kg.

бАLEAD-ACID BATTERY

Lead-acid batteries, invented in 1859 by French physicist Gaston Planté, are the oldest type of galvanic cell battery. Despite having the second lowest energy-to-weight ratio (next to the nickel-iron battery) and a correspondingly low energy-to-volume ratio, their ability to supply high surge currents means that the cells maintain a relatively large power-to- weight ratio. This, along with their low cost, makes them ideal for use in cars, as they aptly provide the highДcurrent required by automobile starter motors. They are also used in vehicles such as forklifts, in which the low energy-to-weight ratio may in fact be considered a benefit since the battery can be used as a counterweight.

Lead-acid car batteries for a 12-volt systemИconsist of six cells of 2.1 V nominal voltage. Each cell contains (in the charged state) electrodes of lead metal (Pb) and lead (IV) oxide (PbO2) in an electrolyte of about 37% (5.99 Molar) w/w sulfuric acid (H2SO4). In the discharged state both electrodes turn into lead(II) sulfate (PbSO4) and the electrolyte loses its dissolved sulfuric acid and becomes primarily water. Due to the freezingpoint depression of water, as the battery discharges and the concentration of sulfuric acid decreases, the electrolyte (including the more modern gellified electrolyte of the gel battery) is more likely to freeze.

Many vendors sell chemical additives (solid compounds as well as liquid solutions) that supposedly reduce sulfate build up and improve battery condition when added to the electrolyte of a vented lead-acid battery. Such treatments are rarely, if ever, effective.

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The following are general voltage ranges for six-cell lead-acid batteries:

- Open-circuit (quiescent) at full charge: 12.6 - 12.8 V - Open-circuit at full discharge: 11.8 - 12.0 V

- Loaded at full discharge: 10.5 V С- Continuous-preservation (float) charging: 13 - 13.2 V

- Typical (daily) charging: 13.2 - 14.4 V

- Equalization charging (for flooded lead acids): 15 - 16 V

- Gassing threshold: 14.4 V

and then slowly to 12.6 V.

и- After full charge the terminal voltage will drop quickly to 13.2 V

The chemical reactions are (charged to discharged):

Anode (oxidation):

Because of the open cells with liquid electrolyte in most lead-acid batteries, overcharging with excessive charging voltages will generate oxygen and hydrogen gas by electrolysis of water, forming an extremely explosive mix. This should be avoided. Caution must also be observed

because of the extremely corrosive nature of sulfuric acid.

CathodeбА(reduction):

Construction of battery

Planté realised that a plate Дconstruction was required that gave a much larger effective surface area. Planté's method of producing the plates has been largely unchanged.

Plates

It would be perfectly feasible to use simple sheet lead plates for the

two electrodes. However, such a construction would only produce around an amp for roughly postcard sized plates, and it would not produce such a

A plate consists of a rectangular lead plate alloyed with a little antimony to improve the mechanical characteristics. The plate is in fact a grid with rectangular holes in it, the lead forming thin walls to the holes. The holes are filled with a mixture of red lead and 33% dilute sulphuric acid (Different manufacturers have modified the mixture). The paste is pressed into the holes in the plates which are slightly tapered on both sides to assist in retention of the paste. This paste remains porous and allows the acid to react with the lead inside the plate increasing the surface area many fold. It should be noted that at this stage the positive and negative plates

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are identical. Once dry the plates are then stacked together with suitable separators and inserted in the battery container. An odd number of plates is always used, with one more negative plate than positive. Each alternate plate is connected together. After the acid has been added to the cell, the cell is given its first forming charge. The positive plates gradually turn the

Сchocolate brown colour of Lead Dioxide, and the negative turn the slate

gray of 'spongy' lead. Such a cell is ready to be used.

Many modern manufacturers use pastes in the plates made directly from Lead Dioxide and Lead, thus avoiding the necessity to form the

charging.иThis causes the plates to gradually shed the paste during their life. It is important that there is plenty of room underneath the plates to catch this shed material. If this material reaches the plates a shorted cell will occur.

plates. Once acid is added, the cell is ready for use.

One of the problems with the plates in a lead-acid battery is that the plates change size as the battery charges and discharges, the plates increasing in size as the active material absorbs sulphate from the acid

during discharge,бАand decreasing as they give up the sulphate during

Separators

Separators are used between the positive and negative plates of a lead

acid battery to prevent short circuit through physical contact, Dendrites (‘treeing’) most and shredded active material. Separators cause some obstructions for the flow of ions i.e. electricity between the electrodes. Separators therefore must have the following characteristics:

- They must be as thin as possible.Д - Electrical resistance must be very high.

- They must beporous– high porosity gives a high rate of flow ofions. - Pore size must be small enough to restrict the flow of colloid parti-

- They are a little larger than the plates to prevent material shorting the plates.

To balance these criteria, the choice of separator shifted from wood to rubber to glass mat to cellulose based separators to sintered PVC separator to microporous PVC/polyethylene separator. An effective separator must meet a number of mechanical properties. Permeability, porosity, pore size distribution, specific surface area, mechanical design and strength, Electrical resistance, ionic conductivity, and chemical compatibility with the electrolyte. In service the separator must have good resistance to acid and oxidation.

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In the battery service condition the following reaction can be shown: PbO2 + 2H + SO4 = PbSO4 + H2O + ½ O2

PbO2 + (oxidisable separator material) + H2SO4 = PbSO4 + (oxidized material)

Moreover, the battery service temperature can be as high as 70 to 80 degrees Celsius. The separator must be capable of resisting thermal degradation as far as possible.

Currently attempts are being made to develop alternatives to the lead-

36 miles per gallon. That may not be as ultra-efficient as some hybrids, but it definitely saves the average family of four a lot of money at the gas pump.

In this article, we'll learn about Ford's brand new, patented hybrid powertrain, take a look at the Escape Hybrid's performance and find out why this car could be a major breakthrough for hybrids in the automotive marketplace.

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