AC 1 Midterm Review (CH 1,3,6, & 11)
Three-phase AC voltage is a combination of three alternating voltage waveforms, each displaced______ electrical degrees apart.
120
Air velocity of______ fpm in building spaces is considered ideal for comfort.
40
Comfort is typically attained at normal cooling and heating temperatures with a relative humidity of about_____ %.
50
______ pressure is any pressure above a perfect vacuum (0 psia).
Absolute
_____ is the movement of air through distribution systems and building spaces,
Air circulation
______ is the process of removing particles and contaminants, such as gases and odors, from air that circulates through air distribution systems.
Air filtration
__________ -rated clothing must be used when working with live electrical circuits.
Arc
_____ pressure is the force exerted by the weight of the atmosphere (gas molecules) on the earth's surface.
Atmospheric
A _____ is the quantity of heat required to raise the temperature of 1 1b of water 1A°F
British Thermal Unit(BTU)
_______ law is a gas law stating that when the pressure on a gas is constant, the volume of the gas is directly proportional to absolute temperature, and when the volume of a gas is constant, the pressure on the gas is directly proportional to absolute temperature.
Charles'
______ is the hazardous location category that refers to the generic hazardous material present.
Class
_______ is a method of heat transfer in which heat is moved from one location to another through the circulation of a substance.
Convection
_____ is the mass of a substance per unit of volume.
Density
__________ is the condition that occurs when a person can sense a difference between themselves and the surrounding air.
Discomfort
_______ is the hazardous location category that refers to the probability that a hazardous material is present.
Division
_______ is the energy produced from the flow of electrons through a conductor.
Electricity
A cogencration power plant is a power plant that changes energy from moving water into electrical energy
F
A conductor is a material that resists the flow of electrons.
F
A person standing on a wet floor has more resistance than a person standing on a dry floor.
F
Air circulation is the speed at which air moves from one point to another through ductwork. a register, or a grill and is measured in feet per minute (fpm).
F
Alternating current (AC) is current that flows in one direction only
F
An insulator is a material with low resistance that permits electrons to flow through it easily.
F
Discomfort is the condition that occurs when a person cannot sense a difference between themselves and the surrounding air.
F
Every twelve months rubber insulating gloves must be laboratory tested by an approved laboratory.
F
Heating equipment is rated in Btu per hour or ton of cooling.
F
In the absorption refrigeration process, a compressor increases the pressure and temperature of a refrigerant so the refrigerant can reject heat to the condensing medium.
F
Rubber insulating gloves or leather protector gloves found to be defective in any way should be discarded or destroyed in the field.
F
Sick building syndrome is an illness that is traced to a building space and attributed to a definite cause.
F
The Independent Electrical Contractors (IEC) are the largest trade association representing manufacturers of products used in the generation, transmission, distribution, control, and end use of electricity.
F
The best method for keeping the air is building spaces comfortable is to adjust the air circulation to maintain building temperatures.
F
The most common type of wire used today is aluminum.
F
There is only one main reason for poor LAQ in building spaces.
F
Tinted-lens safety glasses protect against high-voltage arc hazards.
F
Class_____ protective helmets are used for general service and provide protection up to 2200 V
G
______ is the connection of all exposed, non-current-carrying metal parts to the earth.
Grounding
______ is the energy of a substance resulting from the internal motion of its molecular structure
Heat
_______ is the international unit of frequency equal to one cycle per second.
Hertz
_____ is the amount of moisture, or water vapor, in air.
Humidity
_______ is the production of current flow due to a magnetic field on a coil.
Inductance
______ is the process of removing the source of electrical power from equipment and installing a lock that prevents the power from being turned on.
Lockout
_____ is the amount of matter a substance contains.
Mass
_____ energy is the energy of work.
Mechanical
The purpose of_____ is to convey the safety requirements for persons in the workplace installing electrical conductors electrical equipment, signaling and communications conductors, communications equipment, and raceways.
NFPA 70E®
________ is sine wave distortion from motors and electrical devices that enters a power distribution system directly on the wires/grounds or through the magnetic coupling of adjacent wires.
Noise
_____ law expresses the relationship between voltage, current, and resistance in a circuit.
Ohm's
_____________ is the amount of moisture in air compared to the amount of moisture the air would hold at the same temperature when air is saturated, or full of moisture.
Relative humidity
______ are loves made of latex rubber and are used to provide maximum insulation from electrical shock
Rubber insulating gloves
A(n)_______ pressure gauge is a mechanical pressure gauge that has a small, single-acting spring return cylinder that acts as a pressure-sensing element.
Schrader
_____ heat is the heat applied to or removed from a substance that results in a temperature change.
Sensible
A combination HVAC unit is a self contained heating and cooling unit that has all of the HVAC components contained in one cabinet,
T
A danger tag has the same importance and purpose as a lock.
T
A hasp must be used because energy-insolating devices typically cannot accept more than one lockout/tagout.
T
A transient voltage is a temporary, unwanted voltage that ranges from a few volts to several thousand volts and lasts from a few microseconds to a few milliseconds.
T
AC voltage is either single phase or three phase.
T
Alternating current is current that reverses direction at regular intervals.
T
An arc blast hood is an eye and face protection device that consists of a flame-resistant hood and face shield.
T
C protective helmets are used for special service and provide no voltage protection.
T
Codes and standards ensure that electrical refrigeration and air conditioning equipment is built and installed safely and that every effort is made to protect people from refrigeration and air conditioning electrical hazards.
T
Combustion-power generation plants use steam to produce electricity
T
Dew point is the temperature below which moisture begins to condense.
T
Evaporation is the process that occurs when a liquid changes to a vapor by absorbing heat.
T
HVAC and refrigeration equipment must not be operated unless properly grounded.
T
Humidity is always present in air.
T
Humidity level is controlled by humidifiers and dehumidifiers.
T
In general, the higher the current flow, the higher the amount of work performed by the circuit.
T
Indoor air quality (LAQ) is the condition of indoor air as it relates to contaminant levels and air properties that affect the health and comfort of building occupants.
T
Makeup air is air that is used to replace air that is discharged as exhaust.
T
Personal protective equipment must be worn when installing or maintaining any electrical equipment or motors.
T
Resistance is measured in ohms.
T
Stagnant air is air that is not circulating, typically contains an excess of impurities such as carbon dioxide and lacks sufficient levels of oxygen required to provide comfort
T
Static electricity is an electrical charge at rest.
T
The amount of current that passes through a body or circuit depends on the voltage and resistance of the completed circuit.
T
The amount of ventilation necessary for comfort is determined by the number of occupants and the kind of activity taking place inside the building.
T
The best way to control indoor air pollution in a building space is to eliminate the product or material of contamination from the building,
T
The five major requirements for comfort are proper temperature. humidity, circulation, filtration, and ventilation
T
The purpose of the National Electrical Code® (NEC®) is the practical safeguarding of persons and property from hazards arising from the use of electricity and electrical equipment.
T
Transformers are classified as step-up, step-down, or isolation transformers.
T
______ is the variation of air temperature in a building space that occurs when warm air rises to the ceiling and cold air drops to the floor.
Temperature stratification
______ is the scientific study of the behavior of heat.
Thermodynamics
_____ is the process of reducing air pollution by introducing enough fresh outdoor air into a building to dilute indoor pollutants.
Ventilation
A(n)_____ refrigeration system includes an absorber, generator, condenser, orifice, and evaporator.
absorption
The NFPA specifies live circuit_____ boundaries where are protection is required.
approach
Transient voltages are often caused by lightning or stored voltages being released from______.
capacitors
_____ is the amount of electrons flowing through a conductor.
current
A(n)_____ is a device that removes moisture from air by causing the moisture to condense or be trapped.
dehumidifier
A(n)______ is the result of a body becoming part of an electrical circuit.
electric shock
A(n)_____ indicates areas or tasks that can pose an electrical hazard to personnel and/or HVAC equipment.
electrical safety label
The forms of_____ used in refrigeration and HVAC systems include mechanical, electrical, and heat.
energy
Building HVAC systems typically use______ or boilers to provide heating and air conditioners or chillers to
furnaces
A____ is a designation used to classify gases and dusts.
group
A_____ is a multiple lockout/tagout device.
hasp
A_____ is a device that adds moisture to air by causing water to evaporate into the air.
humidifier
A(n)____ is a device that performs work.
load
A______ HVAC unit is a self- contained building cooling unit that has the components contained in one cabinet.
packaged
A ______ circuit is a circuit that has two or more components connected so that there is more than one path for current to flow.
parallel
All building owners should have________ systems in place to keep HVAC equipment operating at design conditions.
preventative maintenance
The opposition of current flow is called______.
resistance
A______ circuit is a circuit that has two or more components connected so that there is one path for current to flow
series
Two terms that are associated with the health effects of buildings are "building-related illness" and "______________"
sick building syndrome
A_____ transformer has a lower output voltage than input voltage.
step-down
