Study Notes on Mechanical and Electrical Systems

1. Definitions of Electrical and Mechanical Systems

  • Electricity: A form of energy produced by friction, induction, or chemical change.
  • William Gilbert: Known as the Father of Electricity for his studies in electric attraction and force.
  • Classes of Electricity:
    • Dynamic Electricity: Flows through a conductor (electric current).
    • Static Electricity: Accumulates in one location.

2. Sources of Electricity

  • Battery: Stores and supplies direct current.
    • Primary Battery: Delivers electricity immediately upon assembly.
    • Secondary/Storage Battery: Requires charging from an external source.
  • Generator: Converts mechanical energy to electrical energy.
    • Alternating Current Generators (Alternators): Most energy used today.
    • Direct Current Generators: Used for elevators and specific control systems.

3. Dynamo Electric Machines

  • Motors: Convert electrical energy into mechanical energy.
  • Transformers: Change voltage levels.
    • Step-up Transformers: Higher voltage.
    • Step-down Transformers: Lower voltage.
  • Rotary Converters: Change AC to DC and vice versa.

4. Types of Current

  • Direct Current (DC): Flows steadily in one direction.
  • Alternating Current (AC): Periodically changes direction. Frequency is measured in Hertz (Hz); common rates are 60 Hz (lighting) and 25 Hz (motors).

5. Units of Electricity

  • Coulomb: Quantity of electric charge, approximately 6.25 x 10^18 electrons.
  • Ampere: Current flow rate of one coulomb/second.
    • Ampacity: Maximum current a wire can carry without overheating.
  • Volt: Unit of electric potential difference.
  • Ohm: Resistance allowing one ampere to flow when one volt is applied.
  • Watt/Kilowatt: Measure of electrical power; 1 kW = 1,000 W.
  • Watt-Hour/Kilowatt-Hour: Electrical energy units.

6. Ohm’s Law

  • Formula: I=VRI = \frac{V}{R} where I = Current (A), V = Voltage (V), R = Resistance (Ω).

7. Electrical Load Control

  • Load Scheduling: Analyzes and restricts electric load during peak hours.
  • Demand Metering Alarm: Monitors and alarms when demand exceeds a preset level.
  • Ideal Curve Control: Compares actual energy usage to ideal rates.

8. Measuring Electric Consumption

  • KWH Meters: Measure energy in kilowatt-hours (kWh).

9. Building Electrical Systems

  • Branch Circuits: Conductors delivering electricity to outlets (General and Appliance branch circuits).
  • Open Circuit: Disconnected elements prevent current flow.
  • Short Circuit: Low resistance condition allowing excessive current flow.

10. Series and Parallel Circuits

  • Series Circuit: All components connected in a line; same current flows through all. Total resistance is the sum of individual resistances.
  • Parallel Circuit: Current divides among branches; total current is the sum of branch currents.

11. Electrical Units

  • General Purpose Circuit: Supplies lighting or appliance outlets, typically rated at 15 or 20 Amperes.
  • Individual Circuit: Supplies power to a single specific device.

12. Distribution Panel

  • Panel for distributing power and protecting branch circuits.
  • Low-Voltage Circuits: AC below 50 volts, used for systems like doorbells and intercoms.

13. Service Entrance

  • Deliver electricity from utility to building; consist of service conductors and equipment (switch, meter).

14. Fire Protection Concepts

  • Architectural Fire Safety: Strategies for fire prevention, control, and occupant safety in healthcare buildings.
  • Fire Zone Classification: High fire risk, fire load, life risk zones identified for safety measures.

15. Acoustic Considerations

  • Acoustics: Study of sound production and control.
  • Types of Sound: Speech, music, noise.
  • Decibels: Unit to measure sound intensity and loudness.
  • Controlling Sound: Consider room shape, material provision for effective sound management.

16. Lighting Systems

  • Types of lamps include incandescent, fluorescent, and high-intensity discharge (HID) lamps.
  • Ballasts: Control unit for fluorescent and HID lamps.
  • Luminaires: Support and direct light sources.

17. Telecommunication Systems

  • Telephone System: Developed from analog to digital systems; PBX used in building communications.
  • Types of Calls: Call waiting, conference calling, and hands-free options enhance functionality of phone systems.

18. Elevator Systems

  • Definitions and types, including electric and hydraulic elevators. Importance of safety devices and control mechanisms details in relation to their operation.