Batteries Eric Harris, Colin Hepton, Steven Hodgson, Martin Holland, Michael Hudson and Jonathan Ridyard. 14/11/2005
A Brief History Alessandro Volta. Voltaic Pile. 1800s. Silver and Zinc Plates separated by blotting paper soaked in salt water: Connecting the top to the bottom of this pile generated a voltage and current - first battery.
More History Daniell or Crowfoot cell (1800s) Used for doorbells and other static applications. Uses same idea of Voltaic Pile - generation of electricity through ionic compounds.
Diagram of Lead-Acid Battery
How does a lead-acid battery work? Basic premise is an energy conversion from Chemical Energy to Electrical Energy Battery consists of three principal components - Anode (+), Cathode (-) and an electrolyte solution. Anode is made up of Lead Dioxide (PbO 2 ), Cathode is made up of an alloy of Lead and Antimony or Calcium (also known as Sponge Lead). Electrolyte is Diluted Sulphuric Acid (H 2 SO 4 in H 2 O). The Antimony or Calcium plays no part in the reactions.
Fully Charged Battery
Chemical Reactions Upon connecting an electrical load, a chemical reaction takes place. The Sulphate ions (SO 4 2- ) break off and deposit themselves on the electrodes (to form PbSO 4 ). Meanwhile the 2O - ions from the Anode attach to the free H + ions to form H 2 O within the electrolyte. At the Cathode, the Pb attracts SO 4 2- ions. This leaves us free electrons that flow around the circuit, depositing energy they have gained from the chemical reactions into the components - thus we have a flow of ions and an electrical circuit.
For the Chemists!!! H 2 SO 4 2H + + SO 2-4 PbO 2 Pb 2+ + 2O 2- Pb 2+ + SO 2-4 PbSO 4 + 2e - 2H + + O 2- H 2 O (x2)
Fully Discharged Battery
The End of the Battery. The chemical reactions continue, until we are left with two electrodes comprising of Lead Sulphate and an electrolytic solution of water. The battery is fully dead at this point and further energy is not released until the battery is recharged. Recharging the battery is simply an input of energy that reverses the chemical reactions that have taken place (yes, we don t get something for nothing I m afraid unless we talk about Quantum Mechanics, but that s another (temporary and unconnected) story!)
Specific Gravity of a Lead-Acid Battery Measure of state of charge (or concentration of Sulphuric Acid to be more exact) of a Lead-Acid Battery. As battery discharges, this value will decrease so is a good indicator of how charged a battery is. Measured using a Hydrometer - take a sample of the acidwater mixture. Specific Gravity is a density measurement of mass (g) / Volume (ml), corrected for temperature: Correction factor = (0.595 x T/ºF - 12.5) / 100 or 0.03 pts per 5 ºC. The higher this number, the higher the amount of charge on the battery is.
Specific Gravity To calculate the amount of discharge of a battery, we use: Fully Charged Specific Gravity- Present Gravity drop Specific Gravity x100 The fully charged specific gravity is approximately 1.280 and the gravity drop of the battery should be on the battery plate or in the Manufacturer s handbook. Again, this is temperature dependent. The result is a percentage discharge of the battery.
Specific Gravity
A Hydrometer
References www.prestolite.com www.howstuffworks.com www.thesolar.biz www.diy-nos.freeserve.co.uk www.tpub.com www.chemicool.com
WHY DO WE HAVE BATTERIES IN SUBSTATIONS?????
BATTERIES IN SUBSTATIONS NATIONAL GRID HAS SOME 6000 BATTERY STANDBY SUPPLY SYSTEMS TO PROVIDE NO BREAK SUPPLIES TO PROTECTION,TRIPPING CONTROL AND COMMUNICATIONS SYSTEMS THESE SYSTEMS ARE ESSENTIAL TO ENSURE SAFE AND RELIABLE OPERATION OF THE TRANSMISSION SYSTEM TWO DIFFERENT VOLTAGES 110V AND 48V
BATTERIES IN SUBSTATIONS 110V SYSTEM USED FOR OPERATION OF PROTECTION AND CONTROL EQUIPMENT INCLUDING PLANT OPERATION SUCH AS CIRCUIT BREAKER TRIPPING 48V SYSTEM USED FOR POWERING PROTECTION, CONTROL,TELECOMS AND OTHER LIGHT CURRENT EQUIPMENT REQUIRING 48V
BATTERIES IN SUBSTATIONS EACH SYSTEM IS DUPLICATED AND SEGREGATED ELECTRICALLY AND PHYSICALLY WHERE RELAY ROOMS ARE DISTRIBUTED AROUND SITE EACH ROOM WILL BE EQUIPPED WITH A SUPPLY SYSTEM THAT WILL PROVIDE ITS OWN FIRST SUPPLY AND AN ADJACENT ROOMS SECOND SUPPLY
PLANTE CELL BATTERY TYPES
BATTERY TYPES VRLA (VALVE REGULATED LEAD ACID)
BATTERIES IN SUBSTATIONS GENERAL REQUIREMENTS BATTERIES MUST BE OF LEAD ACID CONSTRUCTION VENTED TYPE CELLS MUST CONFORM TO BS6290 PART 2 VRLA CELLS SHALL CONFORM TO BS6290 PART 4 ALL 110V AND 48V SYSTEMS MUST COMPLY WITH NGTS 3.12.4
Connection to Increase the overall voltage In series to obtain required voltage In parallel to increase current capacity
Nominal Voltage s 48Vdc / 110Vdc 48V Protection, Control, telecommunications. 110v Protection, control equipment (circuit breaker tripping)
Lead acid battery cell = 2VDC
What is a 100 Amps / Hour Battery? The discharge of a battery is the amount of time a battery is designed to deliver its full capacity. Our batteries are designed to last for 6 hours 100 Amps / Hours 2 16 Amps 6Hours 3 Yes it will KILL you!!
Replacing Battery Cell 3
What Safety Documents Do You Need To Work On Batteries?
Basic Maintenance of Substation Battery Systems
Types of Substation Battery Systems Three types of system Plante - Lead Acid Glass cell VRLA recombination cell, known as maintenance free or sealed cell Others (Ni-Fe, Ni-Cad, Alkaline) Similar tests are carried out for each type.
Maintaining The Battery System - Cells Firstly we need to check the electrical connections to the battery. Visual checks for corrosion Measure battery voltage and impedance Check all cells have comparable readings, and report any which are significantly different. Wash down the exterior of the cells with a water damped cloth. For Nicad and Plante Systems The electrolyte specific gravity reading must be taken and recorded
Maintaining the Charger Measurements shall be taken for the current and the voltage of the charger. Charger must be switched off to ensure the cells can support a standing load for 5mins
General Battery System Maintenance Temperature readings must be taken for the ambient temperature and also for the temperature at the centre of the cell block. Ensure that battery ventilation apertures are clear and ventilation systems are operational.