Description : Motor starter or controller contacts may become welded together if the contacts _____________. A. open too quickly and arc B. close under excessive pressure C. open or close too quickly D. close under excessive starting current
Last Answer : Answer: D
Description : Excessive heat in an operating motor controller can result from _____________. A. a closed starter contact B. loose connections C. missing arc chutes D. low motor starting torque
Last Answer : Answer: B
Description : To check the three line fuses of a three-phase system consisting of a three-phase motor, you must _____________. A. place the starter in the 'stop' position B. make sure the motor is operating at full ... leads across the 'hot' ends of the fuses D. place the leads across the bottom ends of the fuses
Last Answer : Answer: A
Description : Which of the following actions must be carried out before a voltage tester can be used to test the three line fuses to a three-phase motor? A. The fuses must be removed from the circuit. B. The ... disconnected and tagged. D. Nothing need be done as long as the motor is running under a light load.
Description : The rotor slots of a repulsion-type motor are generally skewed (placed nonparallel to the rotor axis) to _________. A. produce a constant starting torque B. permit a greater air gap with the starter C. permit a smaller air gap with the starter D. reduce eddy current losses
Description : A loud buzzing noise at the contacts of a magnetic controller could indicate _____________. A. weak contact spring pressure B. misalignment of the magnet faces C. excessive line current D. mechanical binding
Description : Motor controller or starter contacts may become pitted and welded together if the contacts _____________. A. open under loaded conditions B. close slowly with light pressure C. open too quickly and arc D. close quickly with proportionate pressure
Description : Due to the operating characteristics of the system, time lag fuses (or dual-element fuses) are necessary for use in _____________. A. main lighting circuits B. motor starting circuit C. emergency lighting circuits D. general alarm circuits
Description : A low-voltage protection circuit is used in electric motor starting equipment to _____________. A. trip circuit contactors when the motor overspeeds due to low voltage B. trip circuit ... voltage without manually resetting D. prevent the motor from restarting automatically on restoration of voltage
Description : Develop the control circuit for star-delta starter used for starting a 3 ∅ induction motor.
Last Answer : Control Circuit for Star-Delta Starter: 1) Automatic Star-Delta Starter: OR 2) Semi- automatic Star-Delta Starter:
Description : When a fluorescent lamp has reached the end of its useful life, it should be replaced immediately, or the resultant flashing may _____________. A. blow the lamp's circuit breaker B. explode, ... fly in all directions C. short circuit the ballast transformer D. damage the starter and the ballast
Description : Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. ... is held below the rated current. D. The field winding is energized for starting purposes only.
Description : Compare pin type and suspension insulators on given points: (i) Position of insulator on cross arm. (ii) Position of conductor on insulator. (iii) Reaction on cross arm. (iv) Possibility of ... Replacement cost (vi) Maximum voltage level (vii) Effect on height of supporting structure. (viii) Life
Last Answer : S.No Points Pin Type insulator Suspension or Disc Type insulator 1 Position of insulator on cross arm It is fixed on top of cross arm by using galvanized steel pin. So it is ... so to maintain minimum ground clearance height of pole increase. 8 Life Less More
Description : The torque produced by a DC motor armature is the product of the force acting at the armature surface multiplied by _____________. A. work done by the armature in one revolution B. effective ... arm at the center of rotation of the armature D. perpendicular distance to its center of rotation
Description : Low voltage releases as used in some shipboard motor starter and control equipment will have which of the following characteristics? A. They trip circuit contactors when the motor starts to overspeed. B. ... coil of the starter. D. They allow the motor to restart upon restoration of normal voltage.
Description : The diagram shown in the illustration represents a _________. EL-0058 A. dual speed, 2-winding motor controller B. navigation running light circuit C. single phase, 2-motor selectable starter D. common fluorescent lighting circuit
Description : When the operating handle of a molded-case circuit breaker is in the mid-position, this indicates that the circuit breaker is _____________. A. on B. off C. reset D. tripped
Description : What is the difference between a Clevis pin and a Cotter pin?
Last Answer : Clevis Cotter Pin
Description : The split - pin is used in... A. Cotter joint B. Knuckle joint C. Universal coupling D. Bolted joint
Last Answer : B. Knuckle joint
Description : Forked - pin joints is also called as... A. Cotter joint B. Knuckle joint C. Universal coupling D. Bolted joint
Description : When maintenance personnel are working on electrical equipment, all supply switches should be secured in the open position and tagged specifically by the _____________. A. watch engineer B. chief engineer or first assistant C. chief electrician D. person performing the repair
Description : If the centrifugal switch or relay used for cutting out the starting winding of a split-phase induction motor fails to open once the motor is in operation, the _____________. A. motor will overspeed B ... C. motor will immediately stall under load D. motor torque will be above normal at rated speed
Description : A characteristic of a wound-rotor induction motor, with a high resistance rotor winding, is _____________. A. low starting torque B. high starting torque C. high speed D. low starting voltage
Description : If an induction motor were to be operated at 90% rated voltage, _____________. A. there would be an increase in starting torque B. starting current would increase slightly C. synchronous speed would decrease slightly D. the slip would increase
Description : A characteristic of an induction motor with a low resistance rotor winding is _____________. A. high starting voltage B. high starting current C. high slippage D. low starting voltage
Description : Reduced voltage applied to a motor during the starting period will _____________. A. result in decreased acceleration time only B. lower the starting current and increase accelerating time C. cause a greater starting torque D. increase the starting current and pump capacity
Description : Shading coils are installed on AC full-voltage starters to _____________. A. eliminate contact chatter B. dissipate opening contact arcs C. delay current build up in the holding coil D. protect the motor windings from momentary starting current overload
Description : The function of amortisseur, or damper windings in a synchronous motor is to _____________. A. eliminate slippage B. provide excitation C. provide starting torque D. increase efficiency
Last Answer : Answer: C
Description : The function of damper windings in a synchronous motor is to _____________. A. eliminate slippage B. provide excitation C. provide starting torque D. increase efficiency
Description : Amortisseur windings are installed in a synchronous motor to _____________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor
Description : The main purpose of the auxiliary winding on a split-phase, single-phase motor is to _____________. A. limit the starting voltage B. increase the starting current C. start the motor D. keep the motor running in the event the main winding should fail
Description : The devices marked 'T' in the illustration are _____________. EL-0080 A. trouble alarm units whose contacts activate when problems arise either on starting or stopping of the motor B. topping ... contactor parts whose contacts start and stop the defrosting cycle of the compressor driven by the motor
Description : Autotransformer starters or compensators are sometimes used with polyphase induction motors to _____________. A. reduce the voltage applied to the motor during the starting period B. increase the voltage for ' ... to be either stepped up or down, depending on the application, to ensure full torque
Description : While starting a main propulsion synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. This indicates the _____________. A. motor has started ... field windings are grounded C. slip rings are dirty D. power transmission cables are grounded
Description : A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting torque of 600 NM. Its starting torque when star delta starter is used:
Last Answer : A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting torque of 600 NM. Its starting torque when star delta starter is used: 200 NM
Last Answer : For starting a D.C. motor a starter is required because it limits the starting current to a safe value.
Description : When a fluorescent lamp fails to light, the trouble can be in the _____________. A. lamp B. starter C. ballast D. all of the above
Description : Propulsion DC motor brush pressures can be calculated by _____________. A. dividing the brush contact area by the spring pressure B. subtracting the brush contact area from the spring pressure C. ... force by the brush contact area D. subtracting the spring pressure from the brush contact area
Description : The pitting of controller contacts can be caused by _____________. A. excessive spring pressure B. insufficient contact pressure C. continuous motor overload D. all of the above
Description : An across-the-line starter provides ___________________. A. maximum torque B. slow starting power C. high speed D. reduced voltage
Description : An across-the-line starter is typically used for which of the following applications? A. Reduced-current starting of large motors B. Low torque starting of small motors C. Low resistance starting of DC motors D. Full-voltage starting of motors
Description : The purpose of a magnetic relay is to _____________. A. open a circuit only in the event of overload B. remotely open and close contacts C. provide overcurrent protection during starting D. relay voltages at increased power
Description : A fuse will 'blow' if _____________. A. an electric motor is stopped suddenly by opening a switch B. the flow of current to the protection device is reversed C. the electrical current exceeds the rated value of the fuse D. unequal resistors are connected in parallel
Description : The electrical device shown in the illustration is a/an _____________. EL-0077 A. operating coil B. indicating lamp C. motor armature D. potentiometer
Description : An electrical connection between the wiring of an electric motor and its metal frame is known as a/an _____________. A. eddy current B. ground C. impedance D. flux leakage
Description : To repair a small electrical motor that has been submerged in saltwater, you should _____________. A. wash it with fresh water and apply an external source of heat B. renew the windings ... electrical parts with a carbon tetrachloride cleaning solvent and then blow dry the motor with compressed air
Description : The direction of rotation of a DC propulsion motor can be changed by reversing the _____________. A. brush holder position B. polarity of the field poles C. brush staggered order D. motor interpole connections
Description : The electrical schematic shown in the illustration represents a/an ____________. EL-0017 A. across-the-line starter B. primary-resistor starter C. autotransformer starter D. part-winding starter
Description : Which of the following conditions will occur if the solenoid coil burns out on a cargo winch with an electrical brake? A. The brake will be set by spring force. B. The motor will overspeed and burn ... the cargo boom will fall. D. Nothing will happen; the winch will continue to operate as usual.
Description : When starting a DC propulsion motor the variable rheostat must FIRST be turned ____________. A. all the way to the run position then quickly back to slow B. to the slow position then gradually moved to full speed C. to the mid position D. quickly to the run position