Electricity supply systems and voltages
Electricity supply systems and voltages. Power generation, transmission, transformer arrangements, voltage levels, losses - 12 questions from a bank of questions
Answer ALL questions. Look for any feedback given if you get an answer incorrect. Keep choosing an answer until you get it correct. CORRECT or INCORRECT answers are indicated at the TOP of the page. A score is given at the TOP of the page when the exercise has been completed. © K.Brown 2015
Which one of the following is a 'renewable' energy source?
? coal ? oil ? gas ? wind
Which one of the following is a 'renewable' energy source?
? coal ? oil ? gas ? solar
Which one of the following is a 'fossil fuel' energy source?
? biomass ? nuclear ? gas ? solar
Which one of the following is a 'fossil fuel' energy source?
? biomass ? nuclear ? oil ? geo-thermal
Which one of the following power sources utilises the heat from the earth?
? biomass ? geothermal ? coal ? nuclear
Why are some power cables installed above ground on poles/pylons rather than underground?
? because cables are safer above ground ? it is cheaper to install cable systems above ground ? cables can be cooled above ground but not underground ? because cables above ground are easier to service/repair
What medium forms the insulation for overhead powerlines?
? p.v.c ? rubber ? air ? glass
Why are electricity transmission voltages high?
? to reduce losses in powerlines ? to increase the volts-drop over long distancess ? to allow higher currents to be carried by the powerlines ? to allow voltage levels to be changed more easily
How are voltage levels changed between power stations to the point of utilisation?
? by using converters ? by using inverters ? by using transformers ? by regenerating the voltages frequently
What is the voltage level generated in a modern power station?
? 132Mv ? 22MV ? 11kV ? 25kV
What is the voltage level carried by the 'super grid'?
? 132Mv ? 275MV ? 132kV ? 400kV
What is the voltage level carried by the 'grid'?
? 11kV ? 33kV ? 400kV ? 132kV
What is the voltage level used by 'heavy industry'?
? 11kV ? 132kV ? 400kV ? 33kV
What is the voltage level used by 'light industry'?
? 25kV ? 132kV ? 400V ? 11kV
What is the voltage level used by 'domestic' premises?
? 230kV ? 11kV ? 400V ? 230V
What transformer arrangement is used to reduce 400kV to 132kV on the electricity transmission grid system?
? star/star ? delta/star ? delta/delta ? star/delta
What transformer arrangement is used to reduce 11kV to voltages than can be used by domestic and light commercial premises?
? star/star ? star/delta ? delta/star ? delta/delta
What name is given to the central connection point of a Star transformer?
? Neutral point ? Earthing point ? Star point ? Central point
How many 'phases' does the UK/EU 'standard' voltage system have, from generation through to final distribution?
? one ? two ? three ? four
Why is it important to balance loads as equally as possible on polyphase systems?
? to reduce losses ? to avoid excessive current loading on one (or more) phases ? to reduce the overall electricity bills ? so a Neutral conductor is not required
What name is given to the point in a substation transformer where the Neutral and Earthing conductors are joined together?
? Neutral point ? Earthing point ? Star point ? Central point
What type of power generation utilises the power of sunlight?
? solar ? geothermal ? nuclear ? biomass