What is an electrical device that uses electromagnetism to change voltage from one level to another or to isolate one circuit from another?
Transformer
What is an electrical service in which service-entrance conductors are run underground from the utility service to the building?
Lateral Service
What is a central location for troubleshooting and servicing motor control circuits?
Motor Control Center
What is a graphic representation of a device, component, or object on a print?
Symbol
A delta connection is a connection that has each coil connected end to end to form what kind of loop?
Closed Loop
What are transformers rated in, which specifies their power output capability?
kVA
What is a grounded metal enclosure that contains factory-mounted bare or insulated conductors?
Busway
What is an electrical wiring sketch showing actual positions of system devices and wiring?
Wiring Diagram
What shows property lines of a building lot, elevation information, compass directions, lengths of property lines, and locations of structures to be built on the lot?
Plot Plan
Standard receptacles include what?
Long (N) slot, short (hot) slot, U-shaped ground hole
What indicates a high-voltage location and condition that could result in death or serious personal injury from an electrical shock if proper precautions are not taken?
Electrical Warning
What kind of current travels a path other than the normal operating path for which a system is designed?
Fault Current
What kind of voltage tends to cause continuous muscular contractions that can prolong the individual’s attachment to a circuit and extra care should be taken around?
High-voltage DC
What is the process of removing the source of electrical power and installing a lock that prevents the power from being turned on?
Lockout
What are the five classes of fires, and what type of extinguisher should be used on electrical fires?
A, B, C, D, and K. Use C on electrical fires
Double-insulated electric safety tools have a recommended maximum use of how many volts and are designed to meet NFPA 70E and OSHA requirements for protecting individuals working with electrical equipment?
1000V
All electrical circuits include multiple points at which ___ or circuit breakers are located.
Fuses
What single word is used to indicate a potentially hazardous situation that, if not avoided, could result in death or serious injury?
Warning
What is done to electrical circuits to safeguard personnel and equipment against the hazards of electrical shock?
Grounding
According to NFPA 70E, only qualified personnel are allowed to work on energized circuits of how many volts or higher?
50V
What is a voltage decrease of more than 10 percent below the normal rated line voltage for a period of longer than 1 minute?
Undervoltage
With many modern electronic components derated to save energy and operating costs, the acceptable voltage range is +5% to ___.
-10%
What is a short, temporary, undesirable voltage in an electrical circuit?
Transient Voltage
Every load, such as a lamp, motor, or heating element, that converts electrical energy into some other form of energy, such as light, rotating motion, or heat, uses ___.
Current
What describes the relationship between voltage, current, and resistance in a circuit?
Ohm’s Law
What is the state where voltage and current in a circuit do not reach their maximum amplitude and zero level simultaneously?
Phase Shift
What kind of connection has two or more devices connected so there is only one path for current flow?
Series
A series circuit contains 3 resistors. One is 25 ohms, another is 50 ohms, and the last is 10 ohms. What is the total resistance of this circuit?
85 ohms. Series: add. Parallel: 1 / 1/P1 + 1/P2 + etc
What is the rate of doing work?
Power
What is the amount of electrons passing a predetermined point in a circuit in 1 second?
Ampere
What is used to verify only the presense of coltage at receptacles, switches, and fuses or circuit breakers?
Voltage Tester, Voltometer
What is an electromechanical device that displays measurements using the mechanical motion of a pointer?
Analog Display
Analog scales are divided using what?
Primary divisions, secondary divisions, and subdivisions
How should a digital display read when measuring an open circuit?
OL
How many jacks does a DMM normally have?
2
What is most commonly used to measure current over 1 A and in applications in which current can be measured easily by placing its jaws around one of the conductors?
Clamp-on Ammeter
In-line ammeters provide the most accurate current measurements when measuring currents less than ___.
1 Amp
Megohmmeters detect what in long wire runs, motor windings, and transformers?
Insulation Failure
Conductive leakage current is kept to a minimum by keeping insulation clean and what?
Dry
A meter’s CAT rating indicates what type of magnitude reading a DMM or other electrical appliance can withstand when used on a power distribution system?
Transient Voltage
Standard and isolated-ground receptacles can be tested using a voltage tester or what?
DMM
A temperature rise of how many degrees or higher requires immediate attention in an electrical system?
100 degrees, 50 degrees requires investigation
When converting energy, electrical loads use what?
Power
Although fuse and circuit breaker conductors are rated for a maximum operating current, they should not be operated continuously at more than how many percent of their rating?
80%
A temperature rise above ambient temperature is expected on electrical equipment carrying current, and the higher the temperature rise, the greater the possibility of equipment what?
Failure
A neutral to ground measured voltage difference of how many volts or higher indicates that the branch circuit is overloaded?
5V
Current unbalances should not exceed how many percent?
10%
In addition to clamp-on ammeters and DMMs, electrical measurements can be taken at a power or distribution panel with power quality meters and what?
Megohmmeters
Fuses and circuit breakers are sized so that they are what type of link in the circuit when the circuit is overloaded or there is a short circuit?
Weakest
Voltage on the secondary of a transformer should not drop below how many percent of the transformers rated output?
10%
What are the three main types of electric motors?
DC, Single-Phase AV, Three-Phase AC
What specifies the operating voltage range in the electrical specifications provided with an HVAC system or motor?
OEM
When measuring voltage, a high voltage fluctuation is an indication of what?
The system is overloaded
What type of motors are small and inexpensive and normally replaced when they fail?
Shaded-pole
What type of switches operate their contacts when a preset temperature is reached?
Thermal Switch
What occurs when voltage at the terminals of an electric motor or other three phase load are not equal?
Voltage Unbalance
What is a common problem associated with heating elements?
No heat, inadequate heat, electrical shock
What is the acceptable voltage percentage range for equipment and receptacles?
Plus 5% to Negative 10%
If low voltage is present out of a control circuit transformer but not into it, the problem is that the transformer if ___ or faulty?
Deteriorated
Motors used in HVAC systems have been selected and installed by the OEM to operate for how long?
An indefinate period of time
When magnetic motor starters are used to control motors, the current and voltage levels have to match what rating on the motor?
Nameplate
The high-voltage side of a transformer is marked with an H and the low voltage side is marked with what?
X
In a basic AC system, a step-down transformer is normally used to reduce the incoming voltage to ___ VAC for the control circuit components.
24VAC
What is an electronic device that controls the direction, speed, torque, and other operating functions of an electric motor, in addition to providing motor protection and monitoring functions?
Motor Drive, VSD, VFD
What type of transformer is the interface used to reduce the voltage from the power circuit to the control circuit?
Step-down
While troubleshooting motor power circuits, what measurements should be taken when a motor is running?
Voltage and Current
What is similar to a clamp-on ammeter in that they both measure the strength of the magnetic field around a conductor?
Current Transformer
Most new motor control applications use what?
Fuses
Dangerous voltage levels exist when?
A motor drive cover is removed and the drive is energized
T/F, Electrical symbols are always shown in their off or de-energized position.
T
T/F, Schematic diagrams show components in their electrical sequence without regard for physical location.
T
T/F, Components used to provide a function of stop are generally wired normally open and in series.
F
T/F, Schematic diagrams are usually harder to read and understand than wiring diagrams.
F
T/F, When a relay is energized, all of its contacts change position.
T
T/F, Wiring diagrams show components mounted in their general location with connecting wires.
F, Pictorial Diagrams
T/F, The way a control symbol is drawn indicates how it is to be connected in a circuit.
T
T/F, Schematics are not important to understand when performing troubleshooting.
F, show logic of circuit not location.
T/F, Electrical symbols all follow a set standard developed by the industry.
T
T/F, Relay contact symbols are laveled in the same manner as the relay coils that control them.
T
When testing a circuit or component with an ohm meter, assuming there is an open, what should your meter display?
OL
What type of diagram shows components in their electrical sequence?
Line Diagram
Dashed lines on a schematic are used to represent which of the following?
Field wiring
Referring to schematics, all symbols are usually shown how?
De-energized
Referring to schematics, components used to provide a function of stop are shown how?
Wired NC and connected in series