Electricity Flashcards
Why is electricity important?
Essential service
Most widely used energy source in hotels (usually)
Highest cost in Utilities Department P&L
Maintaining it properly is critical to the safety of the building and its occupants
Electromagnetism
The force that causes interaction between electronically charged particles
-spinning of turbine creates an electrical current
Direct Current
Flows in one direction, so electricity flows constantly in that direction
ex. batteries and solar cells
Advantages: excellent control, very powerful for certain applications (ex. high-speed elevators)
Disadvantages: not easy to “transform” to different voltage levels, costly to transport, not what goes through power lines
Alternating Current
Flows in 2 directions
ex. travels through wire feeds
Advantages: easily “transforms” to very high voltages and back down to lower voltages
Disadvantages: can lead to low “power factors”
Most commonly supplied electricity
3 Phases (brings more power than one phase to a circuit)
Single Phase
Smaller power requirements
-lighting
-small equipment
Three Phases
Larger power requirements
-most kitchen equipment
-most large mechanical equipment (boilers, pumps, HVAC, chillers)
-large photo copiers
Volts =
Pressure – Electric Potential (gets the electricity Flowing)
Amps =
Flow (current)
Watts =
Power (power of light bulb)
Volts * Amps
Frequency
Hertz (Hz, cycles/sec)
Power Factor =
How efficiently equipment/building uses power
Wash Factor
Never 100% efficient, 90-95% efficiency is good
Electrical Distribution System Components
Service Utility
Transmission Lines
Transformers (substations and sometimes in buildings)
Electrical panel or distribution (switch) panels
Fuses and Circuit Breakers
Circuit to power source
Transformers
Step-up/down power between switch and wherever the power is going to be used
Must be cooled
-oil or dry/air cooled
Distribution panels/switches
Allocate power into different lots of power
Utility riser
Bringing power up/down building
-specific areas/closets -> circuits
Panel distribution
Separate out individual circuits
ex. one for each guestroom, one for each guest bathroom, one for each guest corridor
-within the panel, there is access to the circuit/fuse breaker
Electrical panels must have the following features:
- Enclosed in small, dry rooms or closets
- Locks
- Self-closing doors
-for safety reasons, each circuit has its own fuse/circuit breaker