Electrical Power J. Mitchell for AE-210

What Does Electrical Power Do? Provides Energy for Buildings Provides Energy for Buildings Usually all except Heating Usually all except Heating

How is that Power Used? User’s Equipment User’s Equipment Computers Computers Machinery etc. Machinery etc. Lighting Lighting Major Equipment Major Equipment Emergency Emergency

Review of Basics Power (P) is a constant = Volts * Amps (V*A) Power (P) is a constant = Volts * Amps (V*A) Lost power = Current 2 * Resistance (I 2 *R) Lost power = Current 2 * Resistance (I 2 *R) Therefore making current as small as possible reduces lost power Therefore making current as small as possible reduces lost power Can Transform Power Can Transform Power When Increase Voltage, Decrease Current When Increase Voltage, Decrease Current Therefore long distance at very high voltages Therefore long distance at very high voltages

Distribution of Power Power companies make far from where we need it Power companies make far from where we need it Transform it to high AC Voltage to reduce current so little lost in transmission Transform it to high AC Voltage to reduce current so little lost in transmission Typically 230,000 Volts or higher Typically 230,000 Volts or higher Must have big separation between wires – therefore the transmission lines we see. Must have big separation between wires – therefore the transmission lines we see. “Step” it down as gets to end user “Step” it down as gets to end user Transformers we see at substations on Poles etc. Transformers we see at substations on Poles etc.

Typical Voltages for Distribution VoltageComment >230,000 – 3-Phase Main Distribution – 3 Main wires + Ground 13,200 – 3-Phase Regional Distribution – that’s what Drexel gets 480/277 – 3-phase Often used in building for heavy power 208/120 – 3-phase Main occupant 120 – Single Phase Really just half of 240/120

Transformers Rated in KVA – Kilo-Volt Amperes This is a 1000KVA Transformer

Substation Consists of Consists of Fuse Fuse Meters Meters Transformer Transformer Switches / Panels Switches / Panels Conduits Leading out Conduits Leading out

Distribution Runs In Buildings Chases – Vertical shafts allowing runs Chases – Vertical shafts allowing runs Bus Duct - allows exposed wires Bus Duct - allows exposed wires Conduit & EMT - Conduit & EMT -

Distribution Panels in Buildings Contain Circuit Breakers Contain Circuit Breakers

Outlets & Switches