Bissoy.com
Doctors Medicines MCQs Q&A

If a DC motor starts with jerk when starting, what may be the reason?

If a DC motor starts with jerk when starting, what may be the reason? Correct Answer Pitted starter contact terminals

When contact terminals of 3 or 4 point starter are pitted then DC motor experiences heavy jerks at starting.

  • Pitting is a deterioration process that happens to metals.
  • When contactors have been exposed over a period of time to excessive voltage and heat, pitting eventually creates a surface wherein adequate contact and transfer of electricity is not obtainable.
  • This produces jerks in the starting of DC motor.

Related Questions

An assertion and a reason are given below. Assertion: The phenomenon of nuclear fission generates great energy. Reason: The process in which a nucleus is broken into two parts is called nuclear fission. Choose the answer. A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion. B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. C. Both Assertion and Reason are false. D. Assertion is true but Reason is false.
Consider the following statements: 1. A synchronous motor has no starting torque but when started it always runs at a fixed speed. 2. A single-phase reluctance motor is not self-starting even if path for eddy currents are provided in the rotor 3. A single-phase hysteresis motor is self-starting Which of these statement(s) is/are correct?
In case of synchronous motor, which of the following are true? a. Synchronous motor is not self-starting b. If the rotor poles are excited by field current and the stator terminals are connected to AC supply, motor vibrates. c. Variable frequency supply is used to start synchronous motor. d. By using frequency converter, a synchronous motor can be brought from standstill to its desired speed.
In the following question, sentences of a paragraph have been jumbled and labelled as A, B, C and D. You are required to rearrange the jumbled sentences of the paragraph and mark your response accordingly by selecting the correct option. A: An induction motor can, therefore, be made without electrical connections to the rotor. B: Three-phase squirrel-cage induction motors are widely used as industrial drives because they are self-starting, reliable and economical. C: An induction motor's rotor can be either wound type or squirrel-cage type. D: An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding.
Which of the following statements are correct for dc shunt motor? 1. Speed of a shunt motor is sufficiently constant 2. For the same current input, its starting torque is not high as that of series motor 3. The motor can be directly coupled to a load such as fan whose torque increases with speed Select the correct answer using the code given below.
Consider the following statements: In the above figure, the curves pertain to the DC motor A. Speed vs Armature current characteristic of a DC shunt motor B. Torque vs Armature current characteristic of a DC shunt motor C. Speed vs Armature current characteristic of a DC series motor D. Torque vs Armature current characteristic of a DC series motor
The following items consist of two statements, one labeled as “Assertion (A)” and the other labeled as the “Reason (R)”. You are to examine the two statements carefully and decide if the Assertion (A) and the Reason (R) are individually true and if so whether the reason is a correct explanation of the assertion. Select your answer to these items using the codes given below and mark your answer accordingly. Assertion (A): A sphygmomanometer is always used in conjunction with a means to determine at what pressure, blood flow is just starting, and at what pressure it is unimpeded. Reason (R): Manual sphygmomanometers are used in conjunction with a stethoscope.
In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives. People may see, and hear, and feel all their lives without ____________ learning the nature of things they see. But reason is the mind's eye, and enables us to see why things are, and when and how events may be made to happen ___________ not to happen. The logician endeavours to ____________ exactly what this reason is which makes the power of men. We all, as I have said, must reason well or ill, but logic is the science of reasoning and enables us to distinguish ______________ the good reasoning which leads to truth, and the bad reasoning which every day betrays people into error _________ misfortune. logician endeavours to ____________ exactly what this reason
A centrifugal pump which circulates a hot liquid metal at 500 degree Celsius is driven by a 3600 rpm electric motor. The motor is coupled to the pump impeller by a horizontal steel shaft of dia 25 mm. Let us assume the motor temperature as 60 degree Celsius with the ambient air at 25 degree Celsius, what length of shaft should be specified between the motor and the pump? It may be presumed that the thermal conductivity of the shaft material is 35W/m K and that the convective film coefficient between the steel shaft and the ambient air is 15.7W/square m K
Passengers sitting in a stationary car experience a jerk when the car suddenly starts. This is due to _____