Archives

1. Line diagrams include all of the devices in the system and show the physical relationships between the devices. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Line Diagrams and Wiring Diagrams 2. The control circuit consists of the […]

1. The common function of all controls is to control the operation of an electric motor. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Equipment that is tested and approved by UL is listed in a publication […]

1. Any industrial application that has a pressure-sensing requirement can use a pressure switch. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Pressure Switches and Regulators 2. A limited variety of pressure switches are available for control requirements of […]

1. The operation of a float switch is controlled by the forward or backward movement of a float placed in a water tank. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. An electrode, or stainless steel probe […]

1. A flow switch either closes or opens a set of gates. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Flow Switches 2. Typical applications of flow switches are commonly found in the chemical and petroleum industries. a. True […]

1. Contacts must be selected according to the proper load. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Limit Switches 2. Limit switches may be momentary contact or maintained contact types. a. True b. False ANSWER: True POINTS: 1 […]

1. If two phases of the supply to a three-phase induction motor are interchanged, the motor will stop. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. The sensing network continuously monitors the motor line currents. a. True […]

1. Valves are mechanical devices designed to control the flow of fluids. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. A solenoid valve is a combination of three basic units. a. True b. False ANSWER: False POINTS: […]

1. Electrical contacts must never be permitted to open or close slowly. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Expansion of Metal 2. A bimetal strip is often formed into a spiral. a. True b. False ANSWER: True […]

1. A two-wire control may be a toggle switch. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Two-Wire Controls 2. A two-wire control may be any type of switch having a graduated position. a. True b. False ANSWER: False […]

1. In a three-wire control circuit, when the supply voltage returns after a failure, the circuit is re-energized. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Three-Wire Controls 2. Pilot lights are tested frequently to ensure operation. a. True […]

1. A hand-off automatic switch may be a stand alone control or incorporated into a start-stop push button station. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. A C on an HOA switch indicates that the contacts […]

1. Large motors should be connected directly across the line on startup. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Fractional Horsepower Manual Motor Starters 2. In the event of a power failure, a manual starter motor automatically restarts […]

1. The conventional three-wire, push-button control circuit may be extended by the addition of one or more push-button control stations. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. The operation of each additional push-button control station is […]

1. The direction of rotation of three-phase motors can be reversed by interchanging any two-motor leads to the line. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Push-button interlocking is an electrical method of preventing both starter […]

1. Main or subassembly line conveyors use sequence control. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. The input section of control consists of contactors, starters, solenoids, power magnetic amplifiers, electronic and solid state contactors. a. True […]

1. The term inching is often used when referring to across-the-line starters. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. Neither jogging nor inching prevent a holding circuit. a. True b. False ANSWER: False POINTS: 1 REFERENCES: […]

1. There is a possibility of injury to an operator when the power suddenly resumes after a voltage failure. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. It is desirable to provide some means of automatically restarting […]

1. In a squirrel cage motor, the rotor is constructed of steel laminations mounted rigidly on the motor shaft. a. True b. False ANSWER: True POINTS: 1 REFERENCES: The Motor 2. Locked rotor currents for different motor types vary from […]

1. With primary resistor-type starters, a resistor is connected in parallel in the lines to the motor. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Primary Resistor-Type Starters 2. Primary resistor starters provide closed transition starting. a. True b. […]

1. Most motors are successfully started at 90 percent of line voltage. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Autotransformer Starters 2. The starting transformers are inductive loads. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Autotransformer […]

1. Part winding motors are different in construction from standard squirrel cage motors. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. Part winding motor windings are intended to operate in series. a. True b. False ANSWER: False […]

1. Star-delta motor starting is sometimes called double-delta starting. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. Star-delta motors are similar in construction to standard squirrel cage motors. a. True b. False ANSWER: True POINTS: 1 REFERENCES: […]

1. Magnetic starters can be controlled remotely. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. The magnetic flux produced by the shading coil follows the direction of the flux of the main field. a. True b. False […]

1. Electromechanical devices are used to provide interlocking methods and sequencing control. a. True b. False ANSWER: True POINTS: 1 REFERENCES: The Need for Solid-State Control 2. Solid-state starters are available in ranges up to several hundred horsepower. a. True […]

1. The squirrel cage induction motor is the most widely used industrial motor. a. True b. False ANSWER: True POINTS: 1 REFERENCES: The Motor 2. The design of the motor will determine the percentage of slip. a. True b. False […]

1. A three-phase squirrel cage motor can be wound so that six leads are brought out. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Two-speed, consequent pole motors have one reconnectable winding. a. True b. False ANSWER: […]

1. Four-speed, consequent pole, squirrel cage motors have two reconnectable windings and two speeds for each winding. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Multispeed starters are provided with mechanical and electrical interlocking. a. True b. […]

1. Thephrase“woundrotor”describestheconstructionoftherotor. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Wound Rotor Motors and Manual Speed Control 2. The induced current remains constant in the wound rotor motor. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Wound Rotor […]

1. The number of accelerating contactors depends on the desired number of speeds for the motor. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Push-Button Speed Selection 2. The motor starts slowly with full resistance in the primary circuit. […]

1. The wiring of the accelerating starters and the design of the resistor sections are meant for speed regulation. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. The operation of accelerating contactors is controlled by a timing […]

1. Pilot control devices are often employed to control the operation of a wound rotor induction motor. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Theoverloadrelayforawoundrotormotorcontainstwosetsofcontacts,bothnormallyclosed.​ a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 3. […]

1. An ideal solid-state adjustable speed controller is a modern, energy-saving method of controlling motor speed. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Solid-State Adjustable Speed Controller 2. Electronic circuitry is arranged on plug-in circuit cards. a. True […]

1. A distinguishing feature of the synchronous motor is that it runs without slip at a speed determined by the frequency of the connected power source and the number of poles it contains. a. True b. False ANSWER: True POINTS: […]

1. The most standardized set of symbols in the United States is provided by the NEMA. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Normally open switches are drawn with the movable contact above and touching the […]

1. There is one basic function of synchronous motor control in starting. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Push-Button Synchronizing 2. The principal difference between synchronous motor control and induction motor control is in the control of […]

​ 1. In the accompanying figure, the timing relay coil (TR) is energized with the secondary starter coil (F). a. True b. False ANSWER: False POINTS: 1 REFERENCES: Timed Semiautomatic Synchronizing 2. In the accompanying figure, the timer setting should […]

1. An automatic synchronous motor starter can be used with a synchronous motor to provide automatic control of the startup sequence. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. There are three basic methods of starting synchronous […]

1. By controlling the ohms supplied to the motor windings, a wide range of motor speeds can be obtained. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Application 2. The essential features and parts of DC motors and generators […]

1. The starting of fairly large DC motors requires that current be increased gradually and at the same time resistance must be inserted in series with the armature of the motor. a. True b. False ANSWER: False POINTS: 1 REFERENCES: […]

1. Small DC motors can be connected directly across the line for starting. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Across-the-Line Starting 2. Magnetic across-the-line control of small DC motors is very different from AC control. a. True […]

1. When a DC motor starts, the generated counter emf across the armature is low. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Counter EMF Controller 2. A field accelerating relay is used with starters to control low-cost speed […]

1. DC motors can be operated at a slow speed with a high torque. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Power Conversion and Control 2. If it is necessary to operate the motor above base speed, the […]

1. Plugging controls provide for the rapid stop and quick reversal of motor rotation. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Standard reversing controllers cannot be plugged manually. a. True b. False ANSWER: False POINTS: 1 […]

1. Electric brakes have been in use since the early 1900s. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. An electric brake consists of three friction surfaces, or shoes. a. True b. False ANSWER: False POINTS: 1 […]

1. A motor should be stopped by dynamic braking alone. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. Dynamic braking is a complex but safe method of emergency or safety braking. a. True b. False ANSWER: False […]

1. Electronic brakes require extensive maintenance, adjustment, and periodic replacement of worn parts. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Application 2. Three-phase electric braking reduces the heat buildup in the motor as compared to single-phase braking. a. […]

1. The most economical speed for an electrical motor is about 1800 revolutions per minute. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Directly Coupled Drive Installation 2. It has been suggested that synchronous motors are more expensive to […]

1. In a few cases, industrial machines require power at slow speeds and high torque. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Gear Motors 2. The gear motor is a speed-reducing motor. a. True b. False ANSWER: True […]

1. A frequency changer may be used to vary the speed of AC squirrel cage induction motors. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Variable-Frequency Mechanical Drives 2. There is only one method used for one or more […]

1. DC motors are still used in many industries. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. Variable-frequency drives control motor speed by controlling the frequency of the power supplied to the motor. a. True b. False […]

1. Machinery clutches were originally designed to engage very large motors to their loads after the motors had reached running speeds. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Electrically Controlled Magnetic Clutches 2. The single-face clutch consists of […]

1. Packaged variable speed drives generally operate on AC. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Introduction 2. The AC service in industrial plants can not be converted to direct current for use with DC variable-speed controls. a. […]

1. If you set your alarm clock or clock radio to wake your household in the morning, you have programmed a controller. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Programmable Controllers 2. Input modules sense whether the input […]

1. After new motors and controls are installed, they should be checked for operation under load for an initial period of at least one hour. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Motor Startup 2. Ball-bearing motors can […]

1. Two sets of momentary contacts are usually provided with push buttons. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Push Buttons 2. Some double-break contacts are made of gold. a. True b. False ANSWER: False POINTS: 1 REFERENCES: […]

1. Plunger-type voltage testers are high-impedance devices and require several milliamperes to operate. a. True b. False ANSWER: False POINTS: 1 REFERENCES: Introduction 2. It is often necessary to troubleshoot a circuit with power applied to the circuit. a. True […]

1. Control magnetic relays are used to control small loads. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Control Relays 2. Most of the relays used in machine tool control have double-break contacts. a. True b. False ANSWER: True […]

1. The larger contactor sizes are used to provide remote control of relatively high-current circuits where it is too expensive to run the power leads to the remote controlling location. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Contactors […]

1. Timing relays are used for any application where the operating sequence requires a delay. a. True b. False ANSWER: True POINTS: 1 REFERENCES: Application 2. Pneumatic timers have good repeat accuracy. a. True b. False ANSWER: True POINTS: 1 […]