Unit 7: Power System Components Flashcards
(17 cards)
What are electrical power systems?
System that generates & delivers power to the load.
Have high reliability & efficiency.
Basic Structure of Power Systems
1 = Generation
2 = Transmission
3 = Distribution
4 = Load
What is the phase voltage of the UK grid?
230 V
What is the line voltage of the UK grid?
400 V
What is the frequency of the UK grid?
50 Hz
What is the frequency of stand alone systems e.g aircraft?
400 Hz
Some new aircraft like 787 designed to 800 Hz
Key Component of a Power System [6]
- Power Generators
- Transformers
- Transmission Lines
- Substations
- Capacitors
- Loads
How is power generated in a power system (generally)?
Most maintained by electromechanical conversion using synchronous machines.
Output at 5-30kV (higher = more insulation)
What do OCGT and CCGT stand for?
OCGT = Open Cycle Gas Turbine
CCGT = Closed Cycle Gas Turbine
What are the main types of transformers and their uses? [5]
Substation = step up/down
Distribution = near load centres to reduce V
Service = reduce to household level
Potential = measure high Voltages
Current = measure high Currents
What is the purpose of transmission lines?
High voltage wires on tall towers used to move electricity around (220 - 1200kV)
Most made of aluminium as cheaper & lighter than copper.
Insulators & Their Design
Consist of multiple conical shaped disks around a rod that insulates it.
Conical increases flashover distance & automatically clear off rain.
Methods of protection within electrical power systems
- Circuit Breakers
- Disconnect Switch
- Surge Arrester
Circuit Breakers
3 pole switch at each end of transmission line sections.
Open in event of fault or short circuit.
Disconnect Switch
In series with CB’s to isolate them when open.
Can also be used to sectionalise + isolate sections of a network.
Surge Arrester
Protect vulnerable equipment from surges e.g transformers, substations etc.
What is an Energy Control Centre?
Monitors & Controls power systems by performing Power Dispatching, Security Control & Supervisory Control