•• Q-1: Different between megger and contact resistance meter?
Answers: Megger used to measure cable resistance, conductor continuity, and phase identification where as contact resistance meter used to measure low resistance like relays, contactors.
•• Q-2: Why should be the frequency is 50 Hz only why not others like 45, 95 56 or anything, why should we maintain the frequency constant if so why it is only 50?
Answers: We can have the frequency at any frequency you like, but then you must also make your own motors, transformers or any other equipment you want to use. We maintain the frequency at 50 Hz or 60 Hz cos the world maintains a standard at 50 /60hz and the equipment are made to operate at these frequency.
•• Q-3: Why field rheostat is kept in minimum position while armature rheostat at maximum position?
Answers: In motors at the time of starting the armature resistance is introduced to reduce the high starting current and the field resistance is kept minimum to have high starting
torque.
•• Q-4: Why humming sound occurred in HT transmission line?
Answers: This sound is coming due to ionization (breakdown of air into charged particles) of air around transmission conductor. This effect is called as Corona effect, and it is considered as power loss.
•• Q-5: What is rated speed?
Answers: At the time of motor taking normal current (rated current)the speed of the motor is called rated speed. It is a speed at which any system take small current and give maximum efficiency.
•• Q-6: What is different between grounding and earthlings?
Answers: Grounding means connecting the neutral point of the load to the ground to carry the residual current in case of unbalanced conditions through the neutral to the ground whereas earthing is done in electric equipment in order to protect the equipment in occurrence of fault in the system.
•• Q-7: When we connect the capacitor bank in series?
Answers: we connect capacitor bank in series to improve the voltage profile at the load end in transmission line there is considerable voltage drop along the transmission line due to impedance of the line. So in order to bring the voltage at the load terminals within its limits i.e. (+ or - %6 )of the rated terminal voltage the capacitor bank is used in series
•• Q-8: what are the points to be consider for MCB (miniature circuit breaker selection?
Answers:I(Load)*1.25=I(MAX) maximum current. Mcb specification is done on maximum current flow in circuit.
•• Q-9: What is excitation?
Answer: Excitation is applying an external voltage to DC shunt coil
in DC motors.
in DC motors.
•• Q-10: What is power quality meter ?
Answer: Power Quality meters are common in many industrial environments. Small units are now available for home use as well. They give operators the ability to monitor the both perturbations on the power supply, as well as power used within a building, or by a single machine or appliance. In some situations, equipment function and operation is monitored and controlled from a remote location where communication is via modem or high-speed communication lines. So we can understand the importance of power measurement through power quality meters.
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