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 : Magnetic controller contacts may become welded together during operating conditions as a result of _____________. A. high spring pressure B. high ambient temperature C. an open coil D. low voltage on operating coil
Description : Magnetic controller contacts may become welded together during operation because of _____________. A. excessive magnetic gap B. low contact pressure C. an open coil D. excessive ambient temperature
Last Answer : Answer: B
Description : Magnetic controller contacts may become welded together during operation due to _____________. A. an open coil B. low contact pressure C. excessive ambient temperature D. excessive magnetic gap
Description : If the contacts of a motor starter or controller fail to drop out when the 'stop' button is depressed the ____________. A. contacts are carrying excessive current B. contacts have become welded together C. shading coil is broken D. shading coil is loose
Description : When troubleshooting a magnetic controller, it is found that the contacts are welded together. The most probable cause is _____________. A. excessive operation at low load B. high ambient temperature C. low voltage on the operating coil D. high voltage on the operating coil
Last Answer : Answer: C
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
Description : The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____________. A. designing the contacts to open slowly B. directing the arc into an ... an inverse timed thermal trip for short circuit currents D. instantaneous magnetic trip for overload currents
Description : If a magnetic controller relay fails to drop out when the coil voltage is removed from the relay, the probable cause may be _____________. A. excessive spring tension B. overvoltage C. excessive current D. welded contacts
Description : If a magnetic controller contactor fails to pick up when the coil voltage is applied to the contactor coil, the cause may be _____________. A. overload B. misalignment of the affected contactor contacts C. low spring pressure D. an open contactor coil
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 : A shading coil used in an AC magnetic controller, functions to _____________. A. reduce vibration and noise in the contactor B. prevent flux buildup in the operating coil C. eliminate arcing when the contacts close D. energize the operating coil and 'pull in' the contacts
Last Answer : Answer: A
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 : One function of the movable cams in a drum-type motor controller is to _____________. A. regulate the speed of the motor B. maintain resistance contacts in clean condition C. insulate the operating handle D. limit the amount of load put on the motor
Description : In the illustration, the purpose of part B is to _________. EL-0033 A. increase resistance in series with the contacts as they close to prevent arcing B. create a magnetic field in the steel ... event of an overload D. provide ventilation to the contact when the breaker is close to rated capacity
Description : If the line voltage to the controller shown in the illustration is 440 volts, what voltage is applied across the motor when contacts 'S' close? EL-0080 A. 110 volts B. 220 volts C. 440 volts D. 660 volts
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 : 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 : Can we file the pitted contacts of contactor?
Last Answer : No, use emery paper and etc.
Description : In the illustrated motor controller, the motor fails to start. A voltmeter reading between 1 and 6 reads line voltage, while the voltmeter reading between 2 and 6 reads 0 VAC. The problem is __________. EL- ... in the 'M' coil, 'Ma' contact/start switch or overload contacts D. fuse '10a' is blown
Description : Which of the following statments is true of the illustrated motor controller? EL-0023 A. The low speed is used for starting the motor and when the controller automaticly shifts to High speed. B. The HOL relay ... D. If the overload relay opens for high speed the motor can still be run in low speed.
Description : The 'annunciator module' and 'controller' shown in the illustration together provide for _____________. EL-0094 A. blinking lamp on alarm; testing the lamp and alarm; and logging alarm conditions B ... visual and audible alarms; flashing lamp on alarm; and silencing the horn when answering an alarm
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 : 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 : Complete controller maintenance includes _____________. A. periodic testing of protective devices B. checking for loose or worn contacts and weak springs C. maintaining a sufficient supply of spare parts D. all of the above
Description : Burning of controller contacts, when opening, is prevented by _____________. A. coating the contact surfaces lightly with petroleum jelly B. magnetic blowout coils C. an overvoltage release D. an overcurrent release
Description : Compressed air should not be used to clean motor controller equipment because ________________. A. it may force metallic particles into coil insulation B. the surrounding area may need additional cleaning C. the air blast dries out insulation quickly D. a mask and respirator would be required
Description : The main difference between a motor control circuit containing low voltage protection and low voltage release is that the latter contains _____________. A. a magnetic operating coil B. normally open line contacts C. thermal-overload protection D. a momentary-contact start button
Description : If the three-phase motor, shown in the illustrated schematic diagram, is running in the forward direction, which of the following actions must occur before the motor will reverse rotation? EL-0011 A. Normally-closed ... 'L1' and 'L3' must be interchanged via the 'R' contacts. D. All of the above.
Description : When the motor shown in the illustration is running and the stop button is pushed, which of the following statements will hold true? EL-0010 A. Coil 'M' will now be energized. B. Coil 'CR' will now be energized. C. Contact 'M' will close as contact 'CR' opens. D. Contacts 'M' and 'CR' will open.
Description : When the series field relay "FR" of the winch circuit shown in the illustration is energized during dynamic braking the _______________. EL-0102 A. shunt Field Relay "FR-B.O." is de-energized and contacts ... . shunt Field Relay "FR-B.O." opposes the series coil's flux and sets the mechanical brake
Description : Which of the following conditions indicates a short circuited capacitor when checking its condition with an ohmmeter? A. The capacitor shows charging, but the final resistance reading is appreciably less ... moves quickly to the low resistance side of the scale, then slowly recedes toward infinity.
Description : You are attempting to parallel two AC generators and the synchroscope pointer is revolving slowly in the fast direction. You should _____________. A. use the governor control switch to adjust the incoming ... the 0° position D. use the field rheostat to adjust the speed of the incoming machine
Description : When an operating motor is connected to the controller shown in the illustration, the a path of current flow through the circuit is ____________. EL-0010 A. 'L1', stop button, start button, coil 'CR', 'L2' B. 'L1' ... L2' D. 'L1', stop button, start button, 'CR' contact, 'M' contact, 'CR' coil, 'L2'
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
Description : In a faceplate-type motor starter, the starting arm is held in the 'OFF' position by a/an _____________. A. cotter pin B. magnet C. electrical circuit D. strong spring
Description : To stop the electric motor shown in the illustration, the stop button is depressed, causing ____________. EL-0012 A. coil 'MS' to become de-energized B. contacts 'CR1' and 'MR4' to open C. contacts 'MR1', 'MR2', and 'MR3' to open D. contacts 'MS1', 'MS2', and 'MS3' to open
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 : If a three-phase induction motor is operated under a light load and it develops an open in one of its supply lines, the motor will _____________. A. continue to run, but will vibrate and have reduced ... speed up due to the reduced number of poles C. run cooler due to reduced current flow D. stop
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 : 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 : Which of the listed conditions occur when '4th point lower' is selected on the winch shown in the illustration? EL-0102 A. Master switch contacts '3', '4', '6', '8', '9', & '10' close. B. Contactors '2, 3, & 4M' and ' ... , '7', '8', and '9' close. D. Contactors '1 & 3M' and '1, 2, & 3A' pick up.
Description : Which of the listed conditions occur when selection is made for 'third point hoist' on the winch shown in the illustration? EL-0102 A. Master switch contacts '5', '6', '7', '8', and '9' close. B. Contactors '2M', ' ... ' and '2A' drop out. D. Master switch contacts '3','4', '6', '8', and '9' close.
Description : Electric strip heaters are used in motor controllers to _____________. A. prevent freezing of movable contacts B. keep the components at their design ambient temperature C. prevent condensation of moisture D. minimize resistance in internal circuits
Description : Motor controllers are seldom troubled with grounds because _____________. A. the auxiliary contacts have a high resistance connection B. the contactors and relays are mounted on a nonconducting panel ... individual series-connected units D. there are separate switches for the motor and the control
Description : According to U. S. Coast Guard Regulations (46 CFR), the motor controller for a submersible electric motor driven bilge pump should be installed _____________. A. in the shaft alley B. at the submersible bilge pump C. above the uppermost continuous deck D. at the engine room emergency control panel
Description : A motor controller contains three selector push buttons labeled 'start', 'jog', and 'stop'. When the 'jog' button is pushed, the motor _____________. A. will run continuously after the 'jog' button is ... 'jog' and 'start' buttons are pushed D. will not stop unless the 'stop' button is pushed
Description : RC time constant characteristics, as shown in the illustration, are important in _____________. EL-0086 A. bridge rectifiers for alternator excitation B. timing and pulse shaping circuits C. transistor power amplifier biasing D. motor controller overload protection
Description : Before working on an electric cargo winch master switch or controller, you should _____________. A. spray the gasket surface with a solvent B. drain condensate from the box C. open the circuit breaker in the power supply and tag D. heat the switch box to remove any moisture
Description : If a three-phase induction motor malfunctions and drops to a single-phase (one supply line open) ____________. A. the motor will continue to run if it is not heavily loaded B. more torque will be ... be able to be restarted D. the motor will immediately stop and can only be restarted at no load