ELECTRICITY: form of energy generated by friction, induction, or chemical change MOTORS: converts electrical energy to mechanical energy TRANSFORMERS: transforms one voltage to another Step-Up Transformer: Transformer: 110/120V to 220/240V Step-Down Transformer: Transformer: 220/240V to 110/120V ROTARY CONVERTER: CONVERTER: converts AC to DC, and vice versa AC (Alternating Current): periodically varying in time rate and direction DC (Direct Current): constant Current): constant in time rate and direction (e.g., battery) UNITS -
-
-
-
Quantity: Coulomb: 6.25 x 1018 electrons o Ampere: 1 Ampere: 1 coulomb / second (through given section) o Electric Potential: Volt: electromotive force or potential o Voltmeter: measures EMF, parallel to the circuit Resistance: Ohm: resistance allowing 1 amp o Electric Power: time Power: time rate of doing work o Watt: measuring Watt: measuring unit o Energy: Watt-hours o Ampere: unit of strength of electric current o
OHM’S LAW: I = V/R I = amp, V = volt, R = ohms, W = watts, I = amperes BUILDING CIRCUITS Branch Circuit: complete conducting path carrying current from source Grounding wire for excess electricity: green o Neutral wire (always on): white o Types: o General Purpose Appliance Circuit: specific to appliances Individual Circuit: for large loads (e.g., aircon, pumps, etc.) Series Circuit: components connected in tandem, single path of current flow Parallel Circuit: current divides them Low Voltage SERVICE: supply of utilites Substation: auxiliary power system where voltage is stepped up or down Service Drop: overhead portion of service conductors o Service Lateral: underground portion of service conductors o Service Entrance Conductor: service drop / lateral service entrance Transformer Vault: fire-rated room housing the transformer Switchgear Room: contains building service equipment Switchboard: group of panels with mounted switches, etc.
-
Unit Substation: free standing enclosure housing disconnect switch (solid copper) Feeder o Meter Bank: area where collective meters are mounted Subfeeder: smaller Ø than feeder
LINE SIDE: from supply side LOAD SIDE: to panel board LIGHTNING ROD (air terminal): conducting rods at top of the structure that diverts lighting ½” – 3/8” solid copper rod LIGHTNING ARRESTER: device for protecting electrical equipment from lightning damage SPARK GAP: space between two terminals or electrodes PANEL BOARDS (cut-outs): control and protect subfeeders and branch circuits ELECTRICAL MATERIALS AND EQUIPMENT Conductors: bare (no covering), covered (encased with non-recognized materials), insulated
CABLE: larger than wire CABLE TYPES Armored Cable (AC): enclosed in flexible metal sheath, for BX wiring Metal Clad Cable (MC): each individual enclosed in metal sheath Mineral Insulated Cable (MI): highly compressed refractory mineral, made of compacted magnesium oxide Non-Metallic Sheathed Cable (NM/NMC): moisture-resistant flame-retardant copper or aluminum wire with paper or vinyl covering Shielded NMC (SNM): extruded core, moisture-resistant and flame-retardant Underground Feeder and Branch Circuit Cable (UF): moisture-resistant, for underground Service Entrance Cable (SE or USE): for service wire, single or multi-conductor Flat Cable Assembly (FC) and Flat Conductor Cable (FCC): electronics and fiber optics, for general purposes Medium Voltage Cable (MV): for television, internet Power and Control Tray Cable (TC): installation in cable trays or raceways
INSULATORS: materials that prevent electrode flow Thermoplastics: PVC and UPVC Types: o RHW: Moisture and Heat Resistant Rubber o T: Thermoplastic o TW: Moisture Resistant Thermoplastic o THHN: Heat Resistant Thermoplastic with Nylon o THW: Moisture and Heat Resistant Thermoplastic o THWN: Moisture and Heat Resistant Thermoplastic with Nylon o XHHW: Moisture and Heat Resistant Crosslinked Thermosetting Polyethylene o SA: Silicon Asbestos o AVA: Asbestos and Varnish Cambric o UF: Underground Feeder CONDUITS: circular raceways used to enclose wired and cables STEEL CONDUIT TYPES Rigid Steel Conduit (RSC): 0.017mm, best material for conduit Intermediate Metal Conduit (IMC): 0.071mm, larger inside diameter Electrical Metal Tubing
RACEWAY: holds wires, cables or busbars; metal or plastic (PVC electrical molding) OUTLET: point at wiring system where current is taken Power outlet and lighting outlet RECEPTACLE: wiring device where equipment is plugged into WALL PLATE / FACE PLATE: cover for switches or outlets OVERCURRENT CIRCUIT PROTECTIVE DEVICES: protecting the apparatus from overheating or burning CIRCUIT BREAKER: functions as switch, breaks a circuit with an automatic tripping device GROUND FAULT CIRCUIT INTERRUPTOR: provides ground fault protection WIRING METHODS Knob and Tube Wiring: insulated conductors supported by porcelain knobs and tubes Rigid Metal Conduit Wiring: best and most expensive Rigid Non-Metallic: UPVC Flexible Metal Conduit Wiring Surface Metal Raceway Wiring: wires are supported by thin sheet steel casing Lighting Track Cable Tray / Open Raceway
SWITCH TYPES A. According to Duty
- Normal Duty (ND) - Heavy Duty (HD) - Light Duty (LD)
B. According to Operation Mechanism
C. According to No. of Poles and Throws
- Rotary - Push Button - Toggle or tumbler
- Single Throw - Double Throw
D. According to Service
E. Special Switches
- Service Switch - Power Switches --- General Purpose --- Disconnecting/ Isolating - Wiring Switches --- General Purpose --- 3-way switch --- 2-way switch - Electrolier / Multi-circuit Switches --- Momentary contact --- Dimmer
- Time Controlled - Remote Controlled - Air Switch (clapper) - Knife Switch - Float Switch - Mercury Switch - Key Switch / Card Switch - Automatic Transfer Switch
ACOUSTICS: science of effects of sound on enclosed space SOUND: human ear’s response to pressure fluctuations caused by vibration Physical Qualities of Sound Frequency (f): number of sound ripples per unit time o unit = cycles/sec or Hertz Speed (c): 344 m/sec, does not vary with frequency of sound or loudness Wavelength (λ): C = f λ o C = speed in m/time o f = frequency in cycles/time o λ = meters Intensity: amount of sound power, unit = w/m 2 Characteristics of Sound Loudness: dB (sounds intensity level) Pitch: frequency perceived by human ear
ACOUSTICAL DEFECTS Prolonged Reverberation: due to reflective surfaces and/or large space volume Echo: reflection of original sound Resonance: reinforcement of sound frequency due to sympathetic vibrations Flutter Echo: rapid but repetitive succession of sounds Undue Focusing: caused by concave surfaces
