6 Voltage SourceA device which can produce a continuous force to move the electrons (or, continuous voltage) through the wire connected into the two terminals of the device is called a Voltage Source.There are two types of the Voltage Source which are:Direct Voltage SourceAlternating Voltage Source
7 Direct Voltage SourceA device which produces a continuous direct voltage output is called a Direct Voltage Source.For example: Cells , Battery , DC Generator.A direct voltage is the kind of voltage whose polarity remains the same.Direct Voltage causes the current to move only in one direction continuously.
8 Alternating Voltage Source A device which produces a alternating voltage output is called a Alternating Voltage Source. For example: AC Generator , DC to AC converter etc.A alternating voltage is the kind of voltage whose polarity is reversed periodically. Alternating Voltage causes the current to move in one direction for a period and then in another direction for another period.
9 Ideal Voltage SourceAn Ideal Voltage source is a kind of Voltage source whose internal resistance is zero.Such that the supplied voltage does not changes even if the external load resistance changes.
10 Current SourceA current source is a device which provides the regular flow of electrons or current on a circuit.A current source is a type of voltage source which have enough EMF and surplus electrons so as to produce the flow of electrons.
11 Direct Current SourceThe current source made of a Direct Voltage Source is called Direct Current Source.
12 Alternating Current Source The current source made of a Alternating Voltage Source is called Alternating Current Source.
13 Ideal Current SourceA current source which provides a constant current without any relation with the voltage supplied to the load is called Ideal Current Source.
14 Electro Chemical Primary and Secondary Batteries
15 Electrochemical CellAn electrochemical cell is a device capable of either generating electrical energy from chemical reactions or facilitating chemical reactions through the introduction of electrical energy.
16 Difference between Cell & Battery The cell is the basic single electrochemical unit which converts chemical energy to electrical energy.Battery refers to a stack (group) of Cells
17 CLASSIFICATION OF BATTERIES There are four types of batteries.1. Primary Batteries (or) Primary Cells2. Secondary Batteries (or) Secondary Cells3. Fuel Cells (or) Flow Batteries4. Reserve cell
18 Primary BatteryPrimary cells are those cells in which the chemical reaction occurs only once and the cell becomes dead after sometime. These batteries are used as source of dc power.Eg : Dry cell (Leclanche Cell) and Mercury cell, lithium cell, Carbon-Zinc cell, Silver-oxide cells.Primary cells can be further classified as either wet or dry.
19 Secondary BatteryThese are the cells that can be recharged by passing an electric current through them and can be used again and again. Ex: 1) Lead storage battery 2) Nickel-Cadmium battery 3) Lithium-ion cell battery
20 Comparison between Primary & Secondary cell Primary battery or cell Secondary battery or cellLower initial cost.Higher initial cost.Higher life-cycle cost (Rs/kWh).Lower life-cycle cost (Rs/kWh) if charging in convenient and inexpensive.Disposable.Regular maintenance required.Periodic recharging required.Replacement readily available.Replacements while available, are not produced in the same sheer numbers as primary batteries.
21 Comparison between Primary & Secondary cell Primary battery or cellSecondary battery or cellTypically lighter and smaller; thus traditionally more suited for portable applications.Traditionally less suited for portable applications, although recent advances in Lithium battery technology have lead to the development of smaller/lighter secondary batteries.Longer service per charge and good charge retention.Relative to primary battery systems, traditional secondary batteries exhibit inferior charge retention.Not ideally suited for heavy load/high discharge rate performance.Superior high discharge rate performance at heavy loads
22 Comparison between Primary & Secondary cell Primary battery or cell Secondary battery or cellNot ideally suited for load-leveling, emergency backup, hybrid battery, and high cost military applications.Ideally suited for load-levelling , emergency backup, hybrid battery and high cost military applicationsTraditionally limited to specific applications.The overall inherent versatility of secondary battery systems allows its use and continuing research for a large spectrum of applications.
23 INTRODUCTION TO FUEL CELLS A fuel cell is like a battery which generates electricity from an electrochemical reaction.Fuel cell uses external supply of chemical energy and can run indefinitely, as long as it is supplied with a source of hydrogen and a source of oxygen (usually air). It contains two electrodes i.e. anode and cathode separated by solid or liquid electrolyte.It needs two types of fuel :1) hydrogen2) oxygen(air)