Electrical Engineering Interview questions
The Power factor of generator and transformer depends on the nature of the load that will connected to the generator such as resistive load, capacitive load, and inductive load . The copper loss or insulation losses depends on voltage .So the cu losses depends on the rating current of the load ,that’s why rating generator rating in KVA . But in case of motor has fixed power factor, that is motor has defined power factor and the rating has been mentioned in KW.
The Power generating stations are producing electrical power .This generated power has many characteristics such as voltage, frequency, load . The main power stations are connected to grid .The load on the grid varies with the generating stations efficiency , timing (peak ) and human activity . The generation has to be controlled to meet the demand of load and frequency.
The power generating stations are using different source used to producing electricity so the frequency and voltage will change . Depends on the demand from the grid will decided the power generation .Suppose one generating station shutdown for the yearly maintenance ,that’s power shortage will overcome the load dispatching control things .
The load dispatching specified under Section 32 of Indian Electricity Act 2003.
- Monitor grid operations
- Keep accounts of the quantity of electricity transmitted through the State grid
- To keep the accounts of the quantity of electricity transmitted through the state grid
- Be responsible for optimum scheduling and dispatch of electricity within a State
- Be responsible for carrying out real time operations for grid control and dispatch of electricity within the State through secure and economic operation of the State grid in accordance with the Grid Standards and the State Grid Code.
- Maintain system frequency in 49.0 Hzs to 50.5 Hzs range.
- Load Shedding Implementation.
- Outage planning and monitoring.
- Regulating Generation Load Balance.
Kerala state load dispatch center in: Kalamassery
Consider the two devices need a motor that allows the rotational motion. Taking the consider the construction of the motor its having two parts motor parts and armature parts. Out of these two parts one parts is always stationary and other is moving around its axis allowing rotation of any object that is attached to it.
Ceiling fans have a stationary armature and the motor moves in the counter clockwise direction . Since the blades are attached to the motor ,the ceiling fan rotates in anti-clockwise.
Consider the case of table fan .The motor is stationary armature moves to give motion to the fan blades .because the newton’s third law states that “Every action has an equal and opposite reaction.” the stationary motor gives the armature a push in the opposite direction .This cause the blades of the table fan attached to the armature rotates in clock wise direction
In other reason ceiling fan should blow the air in downward direction and table fan to blow from back side to front .Generally the air blow in the clockwise direction. So the ceiling fan rotates in clock wise direction , it can’t be able to suck air on roof and blow it downward. but a table fan has a large area to suck the air and blow it outwards.
This is the phenomenon associated with high voltage transmission line . Under certain conditions the localized electric filed near energized components and conductors can produce a tiny electric discharge or corona that causes the surrounding air molecules to ionize, or undergo a slight localized change of electric charge.
The main reasons for the corona loses
- Atmospheric Conditions for Corona
- The spacing of the conductors
- Alternating electrical potential difference