Nccer electrical Level 2 Module 2
An ANS-weather-protected motor is one whose enclosure prevents rain and other airborne particles from getting to the electrical components. There may be ANS-2 poles in an induction motor with three phases. There are three stator windings in a three-phase synchronous motor that are 120 degrees apart. After examining the wound rotor motor, you discover that lead L1 is connected to T2, L2, and T3, and that T3 is connected to T1. In order to correct the rotation, you should: ANS-connect L2 to T1, L2 to T3, and L3 to T2. Which of the following is an open motor type as defined by NEMA? ANS-eather-protected Which of the following is a type of completely enclosed motor, as defined by NEMA? ANS-water-cooled If there are any exposed live parts that are operating between the terminals at - ANS-50V or higher, they must be protected. On ANS, which are the stationary windings of AC motors, DC injection braking is used. The ANS-squirrel cage induction motor should be used where the motor is exposed due to the absence of moving electrical contacts. The horsepower rises and falls, or ANS, in direct proportion to speed for a load with constant torque. Which of the following factors influences an AC motor's speed for a given number of poles? - ANS-Frequency A motor's - ANS-output capacity is rated using horsepower. How many motor models is ANS-5 designated by NEMA? In a DC series motor, how much of its full-load torque is developed at starting? - ANS-500% How much higher is the starting current in a split-phase motor than the full-load current? ANS-6 to 8 times The use and installation of motors are covered by ANS in NEC Article 430. The term "slip" best describes it as the difference between an induction motor's synchronous speed and rotor speed. The capacitor-start motor is the single-phase motor type that has the - ANS-highest starting torque ANS-1.15 is the most common service factor found on a motor's nameplate. Motor disconnecting devices must be visible from the controller location, as required by the NEC. On a dc shunt motor, adjusting the voltage and current on the field winding or the - ANS-armature is the primary method for adjusting the speed. The applied voltage's frequency and ANS, or the number of poles, determine the speed of a three-phase squirrel cage induction motor. The -ANS-field poles of a DC motor represent the stationary magnet. A four-pole, 60Hz induction motor operates at a synchronous speed of ANS-1,800 rpm. The - ANS-rated full-load speed is shown on the nameplates in rpm. For speed control and starting current limitation, the wound rotor induction motor (ANS) is utilized. The ANS-round rotor induction motor is the motor that should be used for applications that require frequent starts without overheating. Which of the following uses dynamic braking the most frequently? ANS-Forklifts Which of the following can be found on the nameplate of a motor? ANS-FLA rating Which of the following is true about shaded-pole motors? ANS: They have a high noise level, low efficiency, and low starting torque.ANS-induction motors operate on the basis of a rotating magnetic field. Which of the following motors? For an application that requires adjustable speeds, which of the following motors should be installed first? - ANS-DC When speed control is desired and the required starting torque is high, which of the following motors is used? ANS-compound From no load to full load, which of the following motors maintains constant speed? - ANS-synchronous which kind of
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