Download Electrical Power

Electrical Power
J. Mitchell for AE-210
What Does Electrical Power Do?
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Provides Energy for Buildings
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Usually all except Heating
How is that Power Used?
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User’s Equipment
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Computers
Machinery etc.
Lighting
Major Equipment
Emergency
Review of Basics
Power (P) is a constant = Volts * Amps
(V*A)
2
2
 Lost power = Current * Resistance (I *R)
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Therefore making current as small as possible
reduces lost power
Can Transform Power
When Increase Voltage, Decrease Current
 Therefore long distance at very high voltages
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Distribution of Power
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Power companies make far from where
we need it
Transform it to high AC Voltage to reduce
current so little lost in transmission
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Typically 230,000 Volts or higher
Must have big separation between wires –
therefore the transmission lines we see.
“Step” it down as gets to end user
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Transformers we see at substations on
Poles etc.
Typical Voltages for Distribution
Voltage
Comment
>230,000 – 3-Phase
208/120 – 3-phase
Main Distribution – 3 Main
wires + Ground
Regional Distribution –
that’s what Drexel gets
Often used in building for
heavy power
Main occupant
120 – Single Phase
Really just half of 240/120
13,200 – 3-Phase
480/277 – 3-phase
Transformers
Rated in KVA – Kilo-Volt Amperes
This is a 1000KVA Transformer
Substation
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Consists of
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Fuse
Meters
Transformer
Switches / Panels
Conduits Leading out
Distribution Runs In Buildings
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Chases – Vertical shafts
allowing runs
Bus Duct - allows exposed
wires
Conduit & EMT -
Distribution Panels in Buildings
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Contain Circuit
Breakers
Outlets & Switches