SCIENCE (ELECTRICAL)

Using a block diagram, show how gas, when used as an energy source, is used to produce electricity.​ ​ (a)   ​ (b)   ​

​ (c)   ​ ​ (d)  

• Burn Gas
• Heat water to steam
• Pressured steam rotates turbine
• Rotating turbine turns coils in field

Match the followinList one typical voltage value used in the United Kingdom (UK) for each of the following:g

• 400 kV

• Generation

• 25 kV

• Transmission

• 400/230 V

• Distribution

Identify three ‘renewable’ means of generating electricity used in the United Kingdom (UK).​

​ ​ ​ ​ ​ ​ ​

• Wind power

• Solar Power

• Rain Power

• Hydro power

• Pressure power

Match the followingA 230 V domestic installation is supplied from the public network

• 100a

• a) State the maximum fuse rating (In) fitted in the DNO service cut-out

• ) Outgoing terminals of energy meter

• State the number of live conductors entering the premises.

• 2

• b) State the point at which the consumer’s installation starts.

State three different types of transformer used in electricity supply and distribution networks as identified by their cooling methods.

• Air cooled

  Oil cooled

  Gas cooled

• oil cooled

  petrol cooled

  compression cooled

• blow cooled

  pressure cooled

  gas cooled

• hot cooled

  cold cooled

  water cooled

State two types of losses that can occur in the core of a transformer

• Hysteresis

  flux leakage

• copper loss

  change core material

• Hysteresis

  leakage eddy

• core heat

  loss of power

State what can be done to the core to reduce one of the losses given in previous question

• Laminate core

• position of windings

• Use different core material

• change transformer type

• Use more power

A coil of inductance 0.1 H and resistance 40 Ω is connected to a 230 V 50 Hz supply. Determine, showing all calculations, the impedance of the circuit.

find xl (show all working out) and make note of answer for next question

Mathematical Equivalence

ON

A coil of inductance 0.1 H and resistance 40 Ω is connected to a 230 V 50 Hz supply. Determine, showing all calculations, the impedance of the circuit.

work out Z (impedance) using previous answer

Mathematical Equivalence

ON

Using a suitable scale, draw a power triangle for a 20 kW electric motor having a power factor of 0.8.​

a

b

c

d

15KVAr

25KVA

36-37 degree

20KW