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93 Cards in this Set
- Front
- Back
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When maintaining a heat exchanger, you must adhere to which of the following safety procedures?
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Always wear rubber or plastic gloves, goggles or plastic face shield, rubber or plastic apron, and boots when using trisodium phosphate
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When cleaning the tube sheet and inside shell of a heat exchanger, use a stiff ____ brush or plastic scraper.
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Nonmetallic
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When cleaning a plate-type heat exchanger, you should use caution when handling the plates because ____?
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the edges can be very sharp and may cause injury
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Which type of damage will usually result from current flow between two dissimilar metals
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corrosion
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What percentage of tubes becoming plugged in a tube type heat exchanger will cause the exchanger to function improperly?
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10 %
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Which of the following is NOT a purpose of an auxiliary boiler?
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To provide steam for propulsion
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Two types of auxiliary boiler in use in the CG?
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watertube and firetube
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The temperature at which water boils is called the boiling point or the ?
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saturation temperature
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What is the liquid called that results from saturated steam giving up its heat?
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condensate
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What component controls the start-up and shutdown sequences of an auxiliary boiler?
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Flame safeguard control (FSC)
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Which of the following conditions is NOT generally a hazard associated with auxiliary boilers?
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Diffuser Swirl
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How often should the auxiliary boiler feed water supply system be tested?
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daily
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The alkalinity test has been replaced by direct measurement of ___ on Johnson boilers?
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pH
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The Riley-Beaird flash type evaporator has _____ stages?
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six
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The feedwater for the distilling plant is supplied from the sea and enters the system through a ______ sea chest?
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suction
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The water level appears over halfway in the sight glasses that are mounted on the front of a flash type evaporator unit. This situation could be caused by a restriced flow of the feedwater between flash chambers or by _____
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Faulty operation fo the brine overboard pump through the overthrottling of the brine overboard discharge valve.
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The temperature pilot to the feedwater temp reulator should maintain a temp of _____ degrees F
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170-175
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When the steam feedwater heater shell pressure decreases from approximately 11 inches Hg (vacuum) to 0 psig, you should _____
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perform a cleaning procedure
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What the two basic types of OWS
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vacuum gravity and pressure
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The natural ability of two dissimilar liquids to separate
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coalescing
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Which is NOT a coalescing media that would improve the efficiency of oil removal?
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Emulsified polycarbonate
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What component of OWS employs an optical system based on the principles of light scattering?
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Oil Content detector
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The "clean water inlet" and "clean water outlet" found in OWS are what type of valve?
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Solenoid Valve
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What is Pascals law?
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Pressure that is applied to a confined liquid is transmitted undiminished in all directions and actis with equal force on equal areas
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Which of the following is NOT a safety precaution/guideline that should be considered PRIOR to starting work on a hydraulic system?
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Never move a control valve in any direction as it will cause pressure to build up when the system is disconnected.
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Which of the following is NOT a safety precaution that should be taken WHILE WORKING ON a hydraulic system?
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Completely depressurize the section of the system being worked on, and if possible, remove hydraulic fluid to an approved storage.
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What situation may be a cause of malfunctioning hydraulic system?
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presence of air in the system
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A hydraulic system is found to have a fault that is described as "over-riding work load." How should you correct this problem?
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Adjust, repair, or replace the counterbalance valve
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Two types of filter used on hydraulic systems are?
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Full flow and Proportional flow
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two types of strainers commonly used in hydraulic systems are?
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wire mesh and edge disk
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The PRIMARY indication that a filter element is clogged and needs renewing is?
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a pressure differential that exceeds a specific value
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What are the two types of AC motors?
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Induction and synchronous
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Which type of AC motor is MOST widely used today?
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single phase-induction
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What NEMA code is the most commonly found on the nameplate for AC induction motors?
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B
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Which is not normally identified on a motor's name plate?
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torque
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Which term on the nameplate identifies the rated full load speed of a motor?
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RPM
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Which directive contains a list of teh electrical safety precautions pertaining to working on AC motors?
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NSTM Chapter 300
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this is the most common type of heat exchanger?
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shell and tube
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what type of a heat exchanger does AC&R uses?
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Condenser
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what are the three types of heat exchangers used in the Coast Guard?
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Shell and Tube, Fin and Tube & Plate type
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what is the best method for cleaning shell and tube heat exchanger?
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high-pressure water jet
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who can recover refrigerant?
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Only EPA certified technician can recover refrigerant
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what is one of the degreasing solution used on heat exchangers?
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Trisodium phosphate
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backflushing is only required for?
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seawater cooled plate type heat exchangers
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how do you remove the plates on a plate type heat exchanger?
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rtilt the plates toward the rear of the unit until the top slot is free of the guide bar.
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when do you inspect the heat exchanger
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before and after cleaning. twice
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what should you not use on zinc plug threads?
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teflon tape
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where do most leaks occur for plate type heat exchangers?
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gaskets btu sometimes at cracks or holes in the plates
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what is the primary goal of inspecting a plate type heat exchaner?
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detecting leaks
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what is a boiler?
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a container used to produce steam or hot water.
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what are the two types of boilers?
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firetube and watertube boilers.
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what are the advantages of a firetube boiler?
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inexpensive to build, smple to operate, less maintenance.
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what are the disadvantages of a firetube boiler?
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long warm-up time and weight of unit compare to the amount of steam produced.
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what are the advantages of a watertube boiler?
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less warm-up time & ratio of size and weight to steam produced.
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what are the disadvantages of a watertube boiler?
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requires more maintenance & expensive to build.
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what are the advantages of a firetube boiler?
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inexpensive to build, smple to operate, less maintenance.
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what are the disadvantages of a firetube boiler?
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long warm-up time and weight of unit compare to the amount of steam produced.
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what are the advantages of a watertube boiler?
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less warm-up time & ratio of size and weight to steam produced.
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what are the disadvantages of a watertube boiler?
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requires more maintenance & expensive to build.
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What are the two types of heat?
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sensible heat and latent heat
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what is the term "blowdown" means?
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opening a valve and releasing an amount of boiler water from the boiler into the bilge or deck drain.
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After adjusting the damper, _________ its position into the blower housing for future reference.
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Scribe
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what is the main purpose of the fuel nozzle?
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to atomize fuel
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what is MWT?
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it is Magnetic Water Treatment
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What are some of the benefits of utilizing MWT on boilers?
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eliminates scale build-up. Lessen personnel exposure to tratment and cleaning chemicals, eliminates the need for acid cleaning.
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What is pH rating?
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0-14. 7 is neutral and below that is acidic. above that is alkaline.
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What is the purpose of FSC(flame safeguard control)
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controls the start-up and shutdown sequence of the boiler.
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what is the purpose of tri-cock?
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primarily used as an alternative method for checking boiler water level.
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What four things should be included in feedwater testing?
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alkalinity testing, total dissolved soilds, hot well, make-up water.
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what is the purpose of the distillate cooler?
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to lower the temperature of the distillate as the feedwater is heated.
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what is the required operating temperature of the flash type evaporator?
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170-175 degrees.
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Name three types of coalescing media that improve the efficiency of oil removal?
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metal plates, wire brush, replaceable filters.
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what component employs an optical system based on the principles of light scattering?
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oil content detector
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the clean water inlet and the clean water outlet are what type of valves?
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solenoid valves
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Hydraulics is based upon a principle discovered by?
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French man Blaise Pascal
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Disadvantages of hydraulics?
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initial installation expense and replacement components are high. flammable fluid. operates at high pressure.
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When does pump cavitation occurs?
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Cavitations occur when pump inlet vacuum gets high enough to pull entrapped air out of the hydraulic fluid.
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What is the term displacement in relation to pumps?
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displacement is the quantity of fluid that passes through a pump in one revolution, stroke, or cycle; expressed in cubic inches - in3.
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what causes aeration on pumps?
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when air enters the the fluid on the suction side of the pump. Make the system feels spongy.
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What are the three types of hydraulic pumps?
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Vane, Gear & Piston
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For hydraulic motors, there are two types of rotary actuators. What are they?
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Rotary Motors & Hydraulic Motor.
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hydraulic motors are rated according to their?
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Displacement, torque capacity & maximum operating pressure.
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what is the number one cause of hydraulic motor failure?
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Fluid Contamination
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When doing repairs on hydraulic valves, what should you not use if steam cleaning is not possible?
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Using paint thinner and Acetone.
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what is the symptom of a hydraulic system with a fluid viscosity too high?
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excessive noise
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which motor costs less? AC or DC?
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AC
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What are the main advantages of AC?
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Simple and rugged in design, low cost, low maintenance, and direct connection to an AC power source.
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almost 90 of motors have what type of rotor?
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squirrel cage
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the squirrel cage rotors were given a skew for two main reasons. What are they?
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1. to make the motor run quietly by reducing mgnetic hum and to decrease slot harmonics.
2. to help reduce the locking tendency of the rotor. 3. the rotor teeth tend to remain locked under the stator teeth due to direct magnetic attraction between the two. |
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all single phase motors are generally used for applications up to ___ hp only.
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3/4
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What are the two most widely used parameter for motor standards?
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NEMA which is NAtional Electrical Manufacturers Association and IEC which is International Electrotechnical
Commision. |
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what is the most important step when replacing an AC motor?
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replace with the same type of motor.
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What are the simplest and the most used switches?
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single pole switches.
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