4th year midterm 2021
When testing input devices for a programmable controller they should be tested________ individually as a group
Individually
A__________changes dc voltage into ac voltage inverter converter
Inverter
A(n) ___ held lighting contactor should be used where quiet, energy-efficient operation is required. Select one: a. electrically b. mechanically
b. mechanically
Cooling towers must be thoroughly cleaned on a regular basis to minimize ___. Select one: a. temperature saturation b. power loss c. capillary plugging d. bacteria growth
d. bacteria growth
A plr is a solid state control device that includes_________ timers relays counters all of these
All of these
Starting torque and______of a motor are reduced when a reduced voltage starting method is used to start a motor A.speed B.current c.impedence d.cost of operation
Current
__________can be connected to the input terminals of a programmable controller the nc contacts of a timing relay a foot switch a push button switch any of these
Any of these
Changes to par operating functions can be made using the_____ on the relay selector switches keypad dip switches any of these
Keypad
When testing output devices the programmable controller should be in ______ mode test program run
Program
To reduce electrical noise sensitive analog and digital input devices are connected to a programmable controller with ______ cable integrated gas spacer shielded flat any of these
Shielded
Although the initial voltage may appear normal when testing a transformer, it may not hold up when the transformer is ___ loaded. Select one: a. fully b. moderately c. lightly
a. fully
If a starter fails to pull in when voltage is applied to the coil, the coil may be open or shorted. For an open coil, a meter reading would indicate ___ resistance. Select one: a. infinite ( or OL) b. zero or very low
a. infinite ( or OL)
Thermography utilizes ___ to locate loose electrical terminations. Select one: a. infrared pictures b. digital torque wrenches c. vibration detectors d. all of these
a. infrared pictures
A ___ applies a higher-than-normal voltage between two points in a circuit or piece of equipment and indicates the resistance between the two points. Select one: a. megohmmeter b. hipot tester
a. megohmmeter
For a 9-lead wye-wound 3Ø motor, you should have continuity between leads ___. None of the leads has been field connected - that is, all leads are separated from each other.I. T2 & T7 II. T1 & T4 III. T7 & T9 Select one: a. III only b. II & III only c. II only d. I & II only e. I only
b. II & III only
For predictive maintenance purposes, equipment operation data is ___ to show trends in performance and component characteristics. Select one: a. gathered b. analyzed c. both a and b d. neither a nor b
both a and b
When programming input and output devices for a programmable controller each device must be assigned a__________to link these to processor and data files color code multiplex address any of these
Address
The primary reason to use other than a full voltage starting method is to________ A. Start difficult loads b.reduce starting current C.control a motors speed
Reduce starting current
The process of removing loads from a system during peak periods to reduce electricity costs is referred to as ___. Select one: a. cogeneration b. load shedding c. daylight harvesting d. DER
b. load shedding
A pic consists of a power supply to generate required voltages and a______section input processor output all of these
All of these
The fiber optic communication modules used in programmable controllers are________ used in hazardous locations commonly used for process applications unaffected by noise interference all of these
All of these
When operating at different speeds a motor may be required to deliver______to a driven load constant horsepower constant torque variable torque variable horsepower any of these
Any of these
If a reduced voltage starting method that reduces starting torque too much is selected_______ the overloads will trip the motor wont start both
Both
__________affect the time required for a motor to come to a stop the inertia of the motor and its load friction both
Both
Programmable controllers can be used to control_______actuators linear rotary both a and b
Both a and b
As a motor accelerates up to rated speeds the winding currents are reduced from those at start due to the _____ developed in the motor a.counter emf b.excessive heat c. Phase shift d.all of these
Counter emf
Part winding starting is classified as a reduced voltage starting method but actually has reduced_____when starting A.voltage and current B.voltage and torque C.current and torque
Current and torque
To operate properly the programmable controller input module should supply power to the________devices input output
Input
In the United States, about ___% of the electric energy used is for lighting purposes. Select one: a. 40 b. 60 c. 20 d. 70
20
An ac motor drive is underpowered and or overloaded when the difference in full load voltage and no load voltage at the drives output terminal is greater than____________% 3 5 10 1
3
Compared to an ac motor, a dc motor has______torque output A. A lower B.a higher c.about the same
A higher
A motor will have a _______ acceleration time if the load inertia is higher and the starting torque is lower than a standard motor. longer shorter
Longer
When choosing a programmable controller a_________is generally the first choice for controlling an industrial electrical circuit or system hmi plr plc pac
Plc
______is the reversing of a motor connections to develop a counter torque that will rapidly stop the motors rotation thus serving as a braking method sequencing plugging jogging none of these
Plugging
________can be used to bring a motor to a complete stop dynamic braking plugging friction braking
Plugging friction braking
The_____section of a programmable controller provides the voltage required for internal operation and charging of the internal battery power supply processor input/output programming
Power supply
Pls is an abbreviation for________ product limiting response programmable logic relay periodic linear reactor process layout requirements
Programmable logic relay
When using a programmable controller to control a conveyor system the memory contacts for start PB switches are_________ hardwired programmed
Programmed
The load switch on a drive is set to ct for_____ torque loads variable constant
Constant
When 2-wire control modules are installed on the contactor shown in Figure 414.18, a contact block(s) must also be installed on the contactor so that its contacts are ___. Select one: a. NC b. NO c. both a and b d. neither a nor b
nc
For a dual-voltage, wye-connected, 3-phase motor, the windings are ___-connected for the higher voltage. Select one: a. series b. parallel
series
The power poles shown on the contactor in Figure 414.18 ___ be converted from NO to NC. Select one: a. can b. can not
can
Plcs________be programmed and reprogrammed can can not
Can
A reduction in energy consumption can also be realized by reducing the speed of electric motors true false
True
A______ starter provides gradual voltage increase to motor while starting A.soft B. Across-the-line
Soft
A pic_____ capable of directing a vid to cause a motor to turn at varying speeds is is not
Is
When a starter is set for soft start the motor is generally accelerated over a programmable time period 5-10 0-60 0-30 10-25
0-30
Most motors will operate satisfactorily within ___% (+ or -) of the rated voltage. Select one: a. 20 b. 30 c. 10 d. 40
10
Most motors are not designed to start more than ___ times per hour. Select one: a. 1 b. 1000 c. 10 d. 100
10
When wye delta starting is used the voltage across each motor winding in the wye configuration is approximately________% of the line to line voltage 58 175 225 125
58
A wye delta started requires the use of a________ lead motor for proper operation 9 3 6
6
Although most motor drive perimeters are factory programmed motor________is a parameter that has to be reprogrammed for the specific installation nameplate current stopping mode acceleration time all of these
All of these
A fault code displayed on a motor drive could indicate a __________ loss of phase undervoltage any of these
Any of these
Acceleration time and ramp up time______synomous functions terms associated with motor drives are are not
Are
For a variable torque/variable horsepower vt/vh load an increase in operating speed requires an increase in_________ torque horsepower both
Both
By utilizing an ice storage system, ___ can be saved when chiller or cooling tower loads are shed during peak billing periods. Select one: a. money b. energy c. both a and b d. neither a nor b
Both a and b
Starting a motor using____is considered to be a hard start A.a solid state starter b.an asd C.an fvnr starter D.any of these
C.an fvnr starter
Primary resistor starting works by______ A. Connecting a resistor in series with each motor circuit conductor B.connecting a resistor in parallel with each motor overload C.connecting a set of resistors in parallel with the control circuit
Connecting a resistor in series with each motor circuit conductor
Electric braking is a method of braking in which_________voltage is applied to the stationary windings of a motor after the normal power has been disconnected 1 phase dc 3 phase
Dc
A wye delta motor normally has a higher starting torque when started in forward delta reverse wye
Delta
Programmable controllers__________contain a battery backup do do not
Do
A dc drive provides _____ braking by connecting a resistor across the motor armature after the drive disconnects power to the motor dynamic regenerative
Dynamic
Small drives controlling 3 phase motors can be supplied with ________ power 1 phase 3 phase either
Either
________braking of a motor involves the application of a dc voltage to the windings of an ac motor after ac power is removed friction dynamic reactive electric
Electric
_______current is the amount of current drawn by a motor when operating at nameplate speed A.increment B.locked rotor C.full load D.reaction
Full load
Which starting method is the least expensive and most efficient. Means of starting small horsepower motors? A.primary resistor B.full voltage c.wye-delta D.autotransformer E.part winding
Full voltage
When coasting to a stop after the power has been removed from a dc motor the motor acts as a_______ generator transformer drive none of these
Generator
For a constant torque/variable horsepower ct/vh load an increase in operating speed requires a__________in horsepower decrease increase
Increase
NAND logic utilizes__________switch contacts for connection to programmable controller input terminals normally open normally closed
Normallly closed
______ is used to calculate motor starting current A. Ohms law b.motor start theory c. Inrush calculator. Software D.thess theory of inrush current
Ohms law
Where used in a control circuit horns and sirens are connected to the________terminals on a programmable controller output input
Output
Where used in a control circuit relay coils are connected to the________terminals on a programmable controller output input
Output
For programmable controllers care must be taken when using the force command because it__________designed for the program restores the program to the factory default enables all outputs overrides all safety features all of these
Overrides all safety features
When connected to a programmable controller the actual wiring of a switches contacts(limits,floats,Push buttons, ets.)requires that one switch terminal be connected to a dedicated controller input terminal the other switch terminal is to to be connected to________terminal on the controller the vdc or c input the v-in pr vac output another dedicated input
The vdc or c input
An ac drive controls the torque of an ac motor by varying the________ applied to the motor frequency voltage
Voltage
Which of the following reduced voltage starting methods has the lower cost wye delta autotransformer primary resistor
Wye delta
VAV boxes contain dampers which are used to control the ___. Select one: a. amount of cool or warm air flowing into an area within a building b. amount of water flowing into a chiller c. amount of warm water supplied by a boiler
a. amount of cool or warm air flowing into an area within a building
If the contacts of a mechanically held lighting contactor are closed, the contacts will ___. Select one: a. remain closed during a power failure and after it is restored b. open when a power failure occurs and close when it is restored
a. remain closed during a power failure and after it is restored
A megohmmeter can be used to measure ___ between separate windings in a motor. Select one: a. resistance b. high voltage c. insulation thickness d. all of these
a. resistance
After determining that power is present on the line side of the fuses in a safety switch in the ON position, the fuses can be checked with a voltmeter by placing the meter leads between ___. Select one: a. the line side of one fuse and the load side of the other fuse(s) b. ground and the line side of each fuse c. both a and b d. neither a nor b
a. the line side of one fuse and the load side of the other fuse(s)
Typically, wind turbines and solar cells are complementary because ___. Select one: a. when one is producing peak power the other is producing minimal power b. both produce peak power at the same time
a. when one is producing peak power the other is producing minimal power
Figure 414.18 Coil kits for the contactor shown in Figure 414.18 are available with ___ voltage ratings. Select one: a. AC b. DC c. either a or b d. neither a nor b
ac
Unlike electrically held contactors, the two-wire latching contactor ___ and the coil is removed from the circuit. Select one: a. powers up slowly b. latches in c. turn on the circuit d. discharges quickly
b. latches in
Applying 120 volts to a starter coil rated at 208 volts will ___. Select one: a. overheat the coil windings because the windings are carrying too much current b. not permit the relay to close because too little current is flowing in the coil windings c. cause absolutely no problems, ever d. cause excessive resistance in the control circuit
b. not permit the relay to close because too little current is flowing in the coil windings
Predictive maintenance is the monitoring of wear conditions and equipment characteristics against a predetermined tolerance to ___. Select one: a. troubleshoot malfunctions or failures b. predict possible malfunctions or failures c. both a and b d. neither a nor b
b. predict possible malfunctions or failures
Internal flaws or cracks in metal can be located using ___ that consist of a transmitting and receiving unit. Select one: a. thermal imagers b. ultrasonic testers c. either a or b d. neither a nor b
b. ultrasonic testers
Which of the following are characteristics of solar cells?I. They have a 20- to 25-year life span.II. They contain no harmful materials and can be disposed of in a landfill without posing any hazard.III. They have a low duty cycle and produce peak power at noon each day. Select one: a. II only b. III only c. I & III only d. I, II & III e. I only
c. I & III only
A good solid-state switch indicates ___. Select one: a. a slight voltage drop when closed b. source voltage when open c. both a and b d. neither a nor b
c. both a and b
A set of brushes in a DC motor should be replaced ___. Select one: a. when worn to less than half their original length b. as a set c. both a and b d. neither a nor b
c. both a and b
A(n) ___ can be set to control loads according to the building's schedule on any load changes. Select one: a. light-emitting system b. harvesting system c. building automation system d. attenuating lighting arrester
c. building automation system
A short circuit may be caused by ___ failure. Select one: a. component b. wiring c. either a or b d. neither a nor b
c. either a or b
The purpose for an air handler to mix outside air with inside building air is to reduce the amount of chilled or heated water and to ___. Select one: a. thin out harmful vapors of the unit b. keep the unit cooler c. keep building air healthy d. maintain a balanced airflow
c. keep building air healthy
The earliest forms of energy management involved simple ___ and thermostat-based systems. Select one: a. photocell b. limit switch c. time clock d. EMSS systems
c. time clock
___ is the utilization of sunlight for general illumination within a building. Select one: a. Photosensing b. Regeneration c. Cogeneration d. Daylight Harvesting
d. Daylight Harvesting
Keeping equipment clean helps eliminate ___. Select one: a. conductive circuit paths between exposed terminals and ground b. overheating c. conductive circuit paths between exposed terminals d. all of these
d. all of these
When a motor has been exposed to over-voltage ___. Select one: a. the insulation on the motor windings may have deteriorated b. too much heat has been generated in the windings c. too much current has been flowing through the windings d. all of these
d. all of these
If a starter is emitting a humming noise, this could be caused by ___. Select one: a. misaligned pole faces between the solenoid's frame and the armature b. rust, dirt, or insects between the solenoid's frame and the armature pole faces c. low voltage applied to the coil d. any of these
d. any of these
The cause of nuisance tripping of a starter's OL relay could be because ___. Select one: a. connections at the terminals are loose b. the OLs (heaters) are located in an ambient higher than that of the motor c. the OLs (heaters) are too small for the motor's starting current d. any of these
d. any of these
___ are used to control air flow in ventilation ductwork. Select one: a. Dampers b. Valves c. Either a or b
dampers
Loose or high-resistance corrosion terminal problems at a motor could be caused by ___. Select one: a. vibration b. over-torqued lugs c. overvoltage d. under-torqued lugs e. any of these
e. any of these
Energy management systems can be used to control ___. Select one: a. heating and cooling equipment b. fire suppression systems c. indoor air quality d. automatic window blinds e. all of these f. none of these
e. all of these
Proper O&M (Operation and Maintenance) of a building management system ___. Select one: a. ensures that the design life expectancy of equipment is achieved b. reduces the risks associated with dangerous indoor air quality situations c. mitigates potential hazards caused by deferred maintenance d. can save 5% to 20% on energy bills e. all of these
e. all of these
