Last Answer : If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor.
Description : In accordance with Coast Guard Regulations (46 CFR), a circuit breaker located in the machinery space and installed in a 440V AC system must _____________. A. be dependent upon mechanical ... the maximum asymmetrical shortcircuit current available at the point of application D. all of the above
Last Answer : Answer: C
Description : Electric motors intended for use outside the engine room and boiler room are frequently rated to run at a designed ambient temperature of 40°C. What is the equivalent temperature in degrees Fahrenheit? A. 54.2°F B. 72.0°F C. 104.0°F D. 129.6°F
Description : Lumirhodopsin is stable only at a temperature below (A) –35°C (B) –40°C (C) –45°C (D) –50°C
Last Answer : Answer : D
Description : Which of the following are optimum temperature conditions for making benzenediazonium chloride from aniline? (a) 0°C to 10°C (b) 20°C to 25°C (c) 30°C to 40°C (d) 45°C to 50°C
Last Answer : 0°C to 10°C
Description : Thermophilic micro-organism grow well at temperature– 1) 10°C – 20°C 2) 20°C – 40°C 3) 50°C – 60°C 4) 5°C – 7°C
Last Answer : 3) 50°C – 60°C
Description : Motor name plate data includes '°°C rise'. This indicates the _____________. A. actual running temperature of the winding from no load to full load B. permissible temperature rise ... above normal full load operating temperature D. maximum allowable temperature rise for continuous no load service
Last Answer : Answer: B
Description : On large generators, space heaters are used to ____________. A. keep the machine at ambient tmperature of the machinery space B. maintain rotor and stator winding temperatures above the dew point ... C. prevent condensation in the lube oil D. prevent electrolysis due to condensation in the bearings
Description : Shunt, series, and compound wound motors, are all DC motors designed to operate from _____________. A. constant potential, variable current DC sources B. variable potential, constant current DC ... C. variable potential, variable current DC sources D. constant potential, constant current DC sources
Last Answer : Answer: A
Description : The insulation of electric generators during short idle periods should be _____________. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual ... using strip or space heaters D. relieved of all capacitive charge by grounding the conductors
Description : Two AC generators of the same capacity are operating in parallel. One with a zero speed droop setting and the other with a 5% speed droop. If its capacity is not exceeded, the unit whose ... B. maintain the frequency of the system C. have poor sensitivity characteristics D. have poor power response
Description : In preparing to take insulation resistance readings on a main generator, the windings should be grounded for about 15 minutes prior to the test to _____________. A. allow accurate zeroing of the meter ... the windings D. help the windings to cool to the same temperature as the ground test connection
Description : If a DC motor runs hot, the cause may be _____________. A. high mica condition B. low ambient temperature C. clogged ventilation ducts D. an open in the shunt field
Description : One item listed on the name plate of a cargo pump motor is 'degrees centigrade rise.' This number is based on _____________. A. normal temperature change from cold to hot B. an ambient temperature ... . minimum heat rise from no load to full load D. maximum degrees centigrade rise from absolute zero
Description : Ambient temperature is the _____________. A. amount of temperature rise with no load B. amount of temperature developed by an operating motor C. temperature of the compartment where the motor is located D. normal operating temperature, less the room temperature
Description : Ambient temperature is the _____________. A. amount of temperature rise with no load B. temperature of the compartment where the motor is located C. normal operating temperature, less the room temperature D. amount of temperature developed by an operating motor
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
Last Answer : Answer: D
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
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
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 : 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 : The rated temperature rise of an electric motor is the _____________. A. average temperature at any given latitude B. normal temperature rise above the standard ambient temperature at rated load ... D. permissible difference in the ambient temperature of the motor due to existing weather conditions
Description : Which plant parameters shown in the illustration would produce an alarm if they exceeded preset values? EL-0094 A. SME #7 CYL. EXH. and L.O. TO RDCN. GR. B. L.O. PRESS. TO MN. ENG. and PME #3 MN. BRG. C. L.O. PRESS. TO MN. ENG. and L.O. TO RDCN. GR. D. PME #3 MN. BRG. and SME #7 CYL. EXH.
Description : Electrical machinery insulation will break down more rapidly due to _________________. A. low loading of motors and generators B. frequent megger testing C. high temperatures and vibration D. high operating frequencies
Description : For more complete vessel protection when using an impressed current cathodic system _____________. A. all ship's service alternators have additional temperature sensing devices and a thermal recorder ... with the hull and the propeller shaft is grounded through a slip ring/brush arrangement
Description : Which of the following statements describes the effects of ambient temperature on local action within lead-acid storage batteries? A. Increasing ambient temperature increases local action. B. Increasing ambient ... has no effect on local action. D. At 90°F all local action virtually ceases.
Description : In addition to short circuits and sustained overloads, fuses are likely to blow due to _____________. A. loose fuse clips B. low ambient temperatures C. low contact resistance D. all of the above
Description : An operating characteristic appearing on the name plates of shipboard AC motors is _____________. A. the type of winding B. input kilowatts C. temperature rise D. locked rotor torque
Description : Receptacle outlets aboard ship should be designed so those mounted according to 46 CFR 111 have _____________. A. there must be a sufficient number of receptacle outlets in the crew accommodations for an ... outlet must not have any exposed parts with the plug opening uncovered D. all of the above
Description : What is the purpose of each of the 'signal conditioners' (6000F085 / AH170 / F125) shown in the illustration? EL-0094 A. Convert the varying signal from its particular sensor and deliver a ... the 'setpoint module' in order to keep the pressure or temperature at its sensor at set limits.
Description : The timer element of a reverse power relay cannot be energized unless _____________. A. the power flow is the same as the tripping direction B. the power flow is the opposite to the tripping direction C. the movement of the disk is damped by a permanent magnet D. one generator is motorized
Description : The timer element of a reverse power relay cannot be energized unless _____________. A. one generator is fully motorized B. the movement of the disk is damped by a permanent magnet C. the power flow is the same as the tripping direction D. the power flow is the opposite to the tripping direction
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 : The life expectancy of electrical insulation, is approximately halved for an increased operating temperature of _______________. A. 10°C B. 25°C C. 50°C D. 100°C
Description : The mica used in the commutators of DC machinery is _____________. A. harder than copper B. softer than copper C. the same hardness as the copper D. softer than copper but wears away at a slower rate
Description : The insulation resistance of electric equipment and machinery should be tested for the lowest normal insulation values _____________. A. immediately after shutting down the machine B. every time the brush rigging is ... starting up the machine D. every 30 days whether the machine is in use or not
Description : Before reassembling any machinery, you should _____________. A. replace all bearings regardless of length of service B. apply a heavy coat of oil to all mating surfaces C. clean any corroded surfaces and file all burrs smooth D. coat all parts with alemite grease
Description : Grounds occurring in electrical machinery as a result of insulation failure may result from _____________. A. deterioration through extended use B. excessive heat C. extended periods of vibration D. all of the above
Description : If power were lost to the winch shown in the illustration while in 'second point hoist' the winch would stop. When power is restored the winch would ______________. EL-0102 A. continue to run at ' ... switch' is returned to 'off' closing the 'reset' contacts and then moved to any 'run' position
Description : The _____________ sensor, checks the temperature of the ambient air entering the engine for fine tuning the mixture strength. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature
Last Answer : Answer: d Explanation: The air inlet temperature sensor, checks the temperature of the ambient air entering the engine for fine tuning the mixture strength whereas the engine temperature sensor senses the ... gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.
Description : Which of the following types of motors is often designed for use in correcting power factor? A. Polyphase B. Wound-rotor C. Induction D. Synchronous
Description : Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly fluctuating temperatures, an ambient compensating element must be used. This element consists of ... arm B. conical spring on the contact arm C. second bimetal element D. second electromagnet
Description : An advantage of DC motors over AC motors is that they _____________. A. are less expensive B. require less maintenance C. offer infinite speed variation D. all of the above
Description : Universal motors will operate on AC or DC current, and are generally found in _____________. A. portable tools B. large pump motors C. turbo electric main motors D. forced draft fans
Description : Electrical failures in motors are caused by the breakdown of insulation, which may be caused by _____________. A. penetration of moisture B. accumulation of dirt C. overheating D. all of the above
Description : The failure of ball bearings used in electric motors can result from _____________. A. failure to clean the bearing before repacking B. failure to maintain proper alignment C. excess lubrication forcing the bearing full of grease and eliminating all areas of expansion D. all of the above
Description : Complete maintenance of electrical motors should include periodic checks for machine _____________. A. vibration B. watertight integrity C. speed droop D. reactive power
Description : The operator of electrical motors should keep a constant check on the loads they carry because _____________. A. low loads necessitate frequent insulation cleaning B. exceeding nameplate values shortens ... wasted if full loading is not utilized D. power factor correction methods are load dependent
Description : In the construction of D.C. motors, parts of both the series and shunt fields are wound on the _____________. A. opposite main pole B. rotor core C. interpole D. same main pole
Description : The air gap provided in induction motors should be checked periodically with a feeler gage to detect an unequal air gap and _____________. A. decreased motor magnetizing current B. hysteresis loses C. increased power factor D. mechanical damage to the rotor