Electrical Systems Flashcards
is a form of energy generated by friction, induction or chemical change, having magnetic, chemical and radiant effect
Electricity
Father of Electricity (Electric Attraction & The Electric Force)
William Gilbert
2 General Classes of Electricity
Dynamic Electricity & Static Electricity
A combination of two or more electric cells capable of storing and supplying direct current by electro-chemical means
Battery
Electricity from some external source must be passed through it before it can deliver an electric current (charging the battery).
Main uses are: to supply emergency lighting circuits for hallways, stairways, exits and to energize police and fire alarm systems and certain types of signal systems
Secondary/Storage Batteries
delivers electricity as soon as its parts are assembled, or put together, provided that it is connected to a circuit
Primary Batteries
A machine that converts mechanical energy into electrical energy
Generator
The bulk of electrical energy utilized today is in the form of alternating current, including energy for power and lighting
Alternating Current Generators or Alternators
These furnish electrical energy for elevators, escalators, intercommunicating telephone systems, control of signal systems, and clock systems.
Direct Current Generators
a machine that converts electrical energy into mechanical energy
Motors
For converting one voltage to another, from lower to higher or from higher to lower.
Transformers
Outdoor Transformer
1) H-frame transformer bank
2) Cluster mounted on a single pole
3) Pad Mounted
Indoor Transformer
1) Dry Type
2) Askarel Insulated
3) Oil Insulated
Transformer Rating
1) Step-Up Transformer
2) Step down transformer
for changing alternating current to direct current and vice versa
Rotary Converters
A current which flows at a constant time rate and in the same direction
Direct Current (DC)
A current which is periodically varying in time rate and in direction.
Alternating Current (AC)
Hertz
Named after H.R. Hertz
Unit of Quantity
1) Coulomb
2) Ampere
Ampere
Named after Andre M. Ampere
is the electromotive force or potential difference between two points in an electric field which will move a charge of one coulomb between these points
VOLT
Named after Alessandro Volta
VOlt
The resistance which will allow one ampere of current to flow when one volt is impressed upon it
OHM
Unit of Electrical Potential
Volt
Unit of Resistance
OHm
Unit of Electric power
Watt or Kilowatt
Named after James Watt
Watt
Unit of Energy
Watt-hours or Kilowatt-hours
Ohm’s Law
I (amp) = V (volts) / R (Ohms)
The higher the voltage, the larger the current
the higher the resistance, the lower the current
DC called resistance, abbreviated R
AC called impendence, abbreviated Z
Other equations of Ohm’s Law
W (watts) = I^2R or VI
Whr = I^2Rt
KWhr = I^2R t / 1000
Is the effective utilization of available energy by reducing peak loads and lowering demand charge
Electric Load Control
The installation’s electric loads are analyzed and scheduled to restrict demand by shifting large loads to off-peak hours and controlled to avoid coincident operation
Load Scheduling and Duty-Cycle Control
In conjunction with a duty cycle controller, demand is continuously meters and an alarm is set on when a predetermined demand level is exceeded
Demand Metering Alarm
Also called “rate control” it is an automated version of the demand metering alarm system, where it automatically disconnects or reconnects loads as required
Automatic Instantaneous Demand Control
Sheddable Loads
-Non-essential lighting
-Ventilation Fans
-Space Heating
-Comfort cooling
-Electric Boilers
Unsheddable Loads
-Essential Lighting
-Elevators
-Refrigeration
-Compressors
-Process Equipment
This Controller operates by comparing the actual rate of energy usage to the ideal rate and controls KW demand by controlling the total energy used within a metering interval
Idealcurve Control
are computerized systems which continuously forecast the amount of energy remaining in the demand interval then examine the status and priority of each of the connected loads and decide on the proper course of action
Forecasting Systems
The levying of a charge for power (kw) in addition to the normal energy (kwh) charge
Demand Charge
Conducting elements are disconnected as to prevent the flow of electricity
Open Circuit (Broken or Incomplete)
A condition resulting from bridging any part of a circuit with a conductor of a very low resistance
Short Circuit
the circuit conductors between the final over current protective device and the outlets
Branch Circuit
is one in which the components are connected in tandem.
Series Circuit
(R = R1 + R2 + R3 + R4 + R5)
is one in which the components or loads are so arranged that the current divides between them.
Parallel Circuit (or multiple circuit)
(R = 1 / 1/R1 + 1/R2 + 1/R3)
Supplies outlets for lighting and appliances including convenience receptacles
General Purpose Branch Circuit
Supplies outlets intended for feeding appliances. Fixed lighting is not supplies
Appliance Branch Circuit
is designed to supply a single specific item, such as a motor load or a unit for air conditioner
Individual Branch Circuit
The portion of an electrical system extending from the final overcurrent device protecting a circuit to the outlets served by the circuit
Branch Circuit
A panel for distributing power to other panels or to motors and other heavy power-consuming loads. It controls, distributes, and protects a number of similar branch circuits in an electrical system
Distribution Panel
Of or pertaining to a circuit in which alternating current below 50 volts is supplied by a step-down transformer form the normal line voltage used in residential systems to control doorbells, intercoms, heating and cooling systems, and remote lighting fixtures. Low-voltage circuits do not require a protective raceway
Low-Voltage
A branch circuit that supplies current in several outlets for lighting and appliances
General Purpose Circuit
A branch circuit that supplies current in one or more outlets specifically intended for appliances
Appliance Circuit
A branch circuit that supplies current only to a single piece of electrical equipment
Individual Circuit
General term including materials, fittings, devices, appliances, fixtures, and apparatus used as part of or in connection with an electrical installation.
EQUIPMENT
Current-consuming equipment / fixed or portable, e.g., heating, cooking, and small motor-operated equipment.
APPLIANCE
An accessory, e.g., locknut, bushing, or other part of a wiring system, that is intended to perform a mechanical rather than electrical function
FITTING(S)
The supplying of utilities required or demanded by the public
SERVICE
These are the conductors that extend from the street distribution main or distribution transformer to the service equipment of the building.
Service Conductors
Types of Service Entrance
1) overhead service
2) Underground Service
The service entrance conductors, in the form of bus bars, terminate in the main switchboard and connect to the distribution panel boards through feeder circuits protected by circuit breakers. The main switchboard serves for the control, protection, and metering of the main feeders
MAIN SWITCHBOARD
A feeder circuit is a set of conductors that extends from the main switchboard to a distributing center (panel board), with no other circuits connected between the source and the distributing center. At the center, the feeders terminate at panel boards, which are actually lower-capacity switchboards.
Feeder Circuits
are line extensions of a feeder, fed through a panel board or cutout, or from one distributing center to another, with no other circuit connected between the two distributing centers. A sub-feeder distributes power from the main feeders to smaller local panel boards, called sub-panel boards
Sub-feeder Circuits
The overhead portion of service conductors extending from the nearest utility pole to a building.
Service Drop
The underground portion of service conductors extending from a main power line or transformer to a building.
Service Lateral
are free-standing assemblies of switches, fuses, and circuit breakers that provide switching and feeder protection to several circuits connected to the main source
Switchboard or Switchgear
These are small-capacity conductors that deliver energy to lamps, motors, and other loads within the circuit.
BRANCH CIRCUITS
These serve to control and protect the sub feeders and branch circuits
PANEL BOARDS AND SUB-PANEL BOARDS (also called CUT-OUTS
Types of Service Entrance
1) Overhead
2) Underground
A horizontal single line diagram of the building’s electrical system from the incoming set-vice to the utilization items at the end of the system where the major electrical components are shown as blocks or rectangles.
BLOCK DIAGRAM
When electrical symbols are used in lieu of the blocks, it is called a “one line” or a “single line diagram”.
SINGLE LINE DIAGRAM
Is a vertical line diagram of the major electrical components of the buildings electrical system presented showing the spatial relations between components.
RISER DIAGRAM
provide electric power and illumination essentially for life safety and protection of property during an emergency, such as, electricity for exit lighting, elevators, fire alarm systems, fire pumps and the like.
Emergency Systems
provide power to selected loads not directly involved with life safety, such as, water and sewage treatment plants and industrial machines for manufacturing processes.
Standby Systems
EMERGENCY POWER EQUIPMENT
Central storage batteries are mounted in individual racks and always provided with automatic charging equipment. The greatest disadvantage in its use is that it is limited in the duration of emergency power, usually 1 — % hours. It can, however, start instantaneously and be installed either centrally or installed in small package units strategically located around the building.
Battery Equipment
are machines intended to produce electricity and composed of three components: the machine and its housing (if any), fuel storage tank and the exhaust facilities. The disadvantages in its use are noise, vibration, nuisance of exhaust, need for constant maintenance and difficulties in the handling and storage of its fuel. Additionally, it has longer startup time compared to batteries. However, it has unlimited KVA capacity and can last a lifetime if properly maintained.
Engine-Generator Sets
are materials which allow the free flow of electrons through them. Metals generally have the least resistance in the flow of electric current.
CONDUCTORS
best conductors are precious metals
best conductors are precious metals, such as silver, gold and platinum. Copper and aluminum are the most commonly used materials for conductors.
Types of Conductors
Wires
Cable
Bus Bars
Conductor Sizes
AWG/MCM STANDARD
All conductor sizes from No. 18 (or AWG 1) to No. 10 (AWG No. 0000, also designated 4/0)
Types of Cables
1) Armored cable (Type AC)
2) Metal Clad Cable (Type MC)
3) Mineral Insulated Cable (Type Ml)
4) Non-Metallic Sheathed Cable (Type NM or NMC)
5) Shielded Non-Metallic Sheathed Cable (Type SNM)
6) Underground Feeder and Branch Circuit Cable (Type I-JF)
7) Service Entrance Cable (Type SE or USE)
8) Power and Control Tray Cable (Type TC)
9) Flat Cable Assemblies (Type FC)
10) Flat Conductor Cable (Type FCC)
11) Medium Voltage4 Cable (MV)
are materials which prevent the flow of electrons through them.
INSULATORS
Types of Insulator
-Moisture & heat resistant rubber
-thermoplastic
-Moisture-resistant thermoplastic
-Heat resistant thermoplastic
-moisture & heat resistant thermoplastic
are circular raceways used to enclose wires and cables and are of metal or plastic (PVC)
CONDUITS
PURPOSE OF CONDUITS
To provide a system ground path.
To protect the enclosed conductors from mechanical injury and chemical damage.
To protect people from shock hazards by providing a grounded enclosure.
TYPES OF STEEL CONDUITS
- Heavy-wall steel conduits called “Rigid Steel Conduits” RSC
- “Intermediate Metal Conduit” or IMC
- Thin-wall steel conduits named “Electric Metal Tubing” or EMT.
Standard length of steel conduits
3 M or 10 ft.
are channels or wiring accessories so designed for holding wires, cables and busbars that are either made of metal, plastic, or any insulating medium.
RACEWAYS
- FLOOR RACEWAYS
a.) underfloor raceways
b.) cellular metal floor raceways
c.) cellular concrete floor raceways (precast)
- CEILING RACEWAYS
a.) Header ducts (wireways)
b.) Distribution ducts (laterals)
An outlet is a point in the wiring system at which current is taken to supply utilization equipment. It refers only to the box. A receptacle is the wiring device in which the utilization equipment (appliance) cord is plugged into.
OUTLETS and RECEPTACLES
KIND OF OUTLETS
the complete set-up which establishes connection between the conductor of the flexible
Convenience Outlet or Attachment Cap
includes all devices that are normally installed in wall outlets boxes, including receptacles, switches, dimmers, pilot light, attachment plugs and wall plates.
Wiring Device
common wall outlet is a convenience outlet.
- Lighting Outlet
- Receptacle Outlet
are contact devices installed at the outlet for the connection of a single attachment plug. It includes all receptacles and their matching cap (plug), wall switches, small dimmers, and outlet box-mounted lamps.
RECEPTACLES
are devices for making, breaking, or changing conditions in an electrical circuit under the conditions of load which they are rated.
SWITCHES
TYPE OF SWITCH - ACCORDING TO VOLTAGE
Switches are rated as 250V, 600V, or 5KV as required.
TYPE OF SWITCH -ACCORDING TO INTENSITY OF USE
-Normal duty
-heavy duty
-Light duty
TYPE OF SWITCH - ACCORDING TO TYPE OF SERVICE
-service switch
-power switches
-wiring switches
— A contact device installed at the outlet for the connection of a single attachment plug
Receptacle
a resistor for regulating a current by means of variable resistances.
Rheostat
TYPE OF SWITCH -ACCORDING TO OPERATION MECHANISM
- Rotary switch
- Push-button switch
- Toggle or tumbler switch
TYPE OF SWITCH - ACCORDING TO NUMBER OF POLES AND THROWS
-Poles
-Throws
SPECIAL SWITCHES
- Time Controlled Switches
- Remote Control (RC) Switches
- Air Switch
These are coverings for switches and wall outlets usually made of metal or of phenollic compound (Bakelite).
WALL PLATES OR FACEPLATES
is a switch device. Instead of handle-operated, movable uses two contact blocks of silver coated copper, which are forced together to make or break a circuit.
Contractor
is a small electrically- operated contactor.
Relay
a protective plate surrounding an electric outlet or light switch.
Faceplate
are devices whose sole purpose is to protect insulation, wiring, switches and other apparatus from overheating or burning, due to overloads, to faults or to short circuits, by automatically cutting off the circuit.
OVER-CURRENT CIRCUIT PROTECTIVE DEVICES
is a device consisting of an alloy link of wire with a low melting temperature which is inserted in the circuit, in such a way, that all current which passes through the circuit, must also pass through this metal.
Fuse
TYPES OF FUSES
- Plug Fuse
- Cartridge Fuse
- Open Link Fuse
an overall current pratective device with a circuit opening fusible element which breaks when there is an over current in the circuit.
Fuse
STANDARD TYPE OF FUSES
A. Nonrenewable plug fuse
B. Nonrenewable knife blade fuse
C. Nonrenewable dual element time delay ferrule cartridge fuses
D. Nonrenewable high interrupting capacity current limiting fuse (dual element)
E. Nonrenewable miniature fuse
is an over-current protective device designed to function as a switch, or it can be manually tripped and thus act as a circuit switch.
CIRCUIT BREAKERS
Most circuit breakers are equipped with both thermal and magnetic trips.
Tripping
similar in action to a thermostat. Heat generated by excessive current causes an element to move and trip the latching mechanic of the breaker thus opening the breaker contacts and thereby the circuit.
Thermal Trip
comprises a coil with a movable core. On short circuits, magnetic forces actuate the core which trips the circuit breaker latch.
Magnetic Trip
is an over current protective device that will provide ground fault protection as well as function as an ordinary circuit breaker.
GROUND FAULT CIRCUIT INTERRUPTERS (GFCI or GFI)
popularly known as “panel” or “electrical panel”, it is simply the box wherein the protective devises are housed from which the circuits and busbars terminate.
Panel Boards
TYPES OF PANELBOARDS
- Lighting Panelboards (LP)
- Power or Motor Panelboards (PP)
- Distribution Panelboards (DP)
an instrument which responds to the changes in temperature and consists of sensitive elements which expands and contracts according to the degree of heat.
Thermostat
refers to the upstream side of a load or device; or it refers to where the current will come from The downstream side of the device is called the “Load Side”.
Line side
are free standing assemblies of switches, fuses, and/or circuit breakers whose function normally is to provide switching and feeder protection to a number of circuits connected to a main source.
SWITCHBOARDS
TYPES OF SWITCHBOARDS
- Live Front
- Dead Front
(Transfer Load Centers) an assembly of primary switch-fuse-breaker, step-down transformer, meters, controls, busbars and secondary switchboard. It is used to supply power from a primary voltage line to any large facility.
UNIT SUBSTATIONS
an obsolete wiring system consisting of single insulated conductors secured to and supported on porcelain knobs and tubes.
KNOB AND TUBE WIRING
is the best and most expensive among the usual type of wiring.
RIGID METAL CONDUIT WIRING
A separate classification for rigid conduits are those that are of such materials as fiber, asbestos-cement, soapstone, rigid polyvinyl chloride (PVC),and high density polyethylene.
Rigid Non-Metallic Conduit
Its installation is much easier and quicker than that of rigid metal conduits.
FLEXIBLE METAL CONDUIT WIRING
same construction as the flexible conduit, except that it is covered with a liquid-tight jacket. The trade name “Sealtite” refers to this product.
Liquid-tight Flexible Metal Conduit
consists of rubber or thermoplastic covered wire protected from injury to a certain extent from dampness by one or two layers of flexible steel armor.
ARMORED CABLE WIRING (BX WIRING)
the wires are supported on a thin sheet steel casing. The raceway is installed exposed, being mounted on the walls or ceiling.
SURFACE METAL RACEWAY WIRING
a field installed rigidly mounted square structural channel (1 — 5/8” standard) designed to carry 2 to 4 conductors (No. 10 AWG) and will act as light duty (branch circuit) plug-in busways
FLAT CABLE ASSEMBLIES
a panel in a casing or box that can readily be removed, as by punching, hammering, or cutting, to provide an opening into the interior.
Knockout
any of various devices for joining two or more conductors bundled together, without a permanent splice, and inserting them into a small clip-like tube tightened with a screw.
Connector
a rigid metal housing for a group of buses insulated from each other and the enclosure. Also called a “bus duct”.
Busway
a factory-assembled channel with conductors for one to four circuits permanently installed in the track that will act as light duty (branch circuit) plug-in busways.
LIGHTING TRACK
is a continuous open support for approved cables.
CABLE TRAY … OPEN RACEWAY
FLOOR RACEWAYS , 3 types
- Underfloor Ducts (UF)
- Cellular Metal Floor Raceway
- Precast Cellular Concrete
under-the-ceiling raceways composed of header ducts and distribution ducts separate for power and telephone cabling.
CEILING RACEWAY SYSTEMS
are ceiling raceways that are pre-wired in the factory and plugged in where required.
PRE-WIRED CEILING DISTRIBUTION SYSTEMS
a single, enclosed, tubular space in a floor made of precast cellular concrete slabs, the direction of the cell being parallel to the direction of the floor member.
Cell
MDP
MAIN DISTRIBUTION PANEL
EP
EMERGENCY PANELBOARD
