Electrical Engineering Q/A 30-40

 30: What are different types of Steam boilers used in Thermal Power Plants?
Different type of boiler used in thermal power plants are:
Fire tube boiler
Water tube boiler
Natural Circulation boiler
Forced Circulation boiler
Once through boiler 

31: What are different types of Pulverizes?
Different types of Pulverizers are:
Ball tube mill
Ring roll mill
Hammer mill
Attrition type mil 

32: What is the capacity of CPU of Remote Terminal Unit (RTU)?
Remote Terminal Units (RTUs) contain generally microprocessor having 16 bit or 32 bit (eg: 68302 or 80386) 

33: What is the programmable language used in PLC?
The general language program consists of Ladder Diagrams. Relay logic control scheme is represented in Ladder diagrams. Alternative languages uses Boolean representation of these control schemes as base of the computer representation. 

34: How Generator Transformer is cooled in Thermal Power Plant?
MVA power rating of the Generator Transformer will be equal to the alternator. Hence lot of heat will be generated while generator transformer is under operation. Oil Forced Air Forced (OFAF) type of cooling is employed for generator transformer. 

35: Where Servomechanism is used?
Servomechanism is used in control system where the output is pertained to vary the mechanical position of a device.
Servo Mechanism is widely used in Governor value position control mechanism used in the power plants where speed of the turbine is taken and processed using the transducers and final control element is brought as mechanical movement of the value. Now a days Governor value control is done with Electronic controls using power Thyristors. Servomechanism is also widely used in the robotic hand movements.

36: Do transients occur in power lines only?
No, they can occur in any line made of metal such as communication lines, telephonic lines etc. 

37: What is rated in Electrical Eng?
Rated voltage, rated current, rated torque are the maximum value at which machine will be operating safely. These are the value given by manufacturer and beyond these value, machines performance will drop. It may have some faults or may be even damaged.

38: Say there is air conditioner of 1Ton, what does that mean?:
You could define that air conditioner are
basically designed to remove heat from
inside the room of specific area. So it means
the air conditioner is able to remove 1000
kilocalories of heat in an hour.
A ton is the cooling capacity of an air conditioning system. One ton is equal to the amount of heat required (288,000 Btu) to melt one ton of ice in a 24-hour period. A one-ton air conditioner is rated at 12,000 Btu per hour (288,000/24). A two-ton unit would be rated at 24,000 Btu per hour.
A BTU is a British Thermal Unit, approximately the amount of heat you get from burning one kitchen match all the way down. 

39: Why can't we store AC in batteries instead of DC?
AC supply can never be stored in a battery because Ac changes its polarity (poles) 50 times in a second when frequency is 50Hz. Therefore if AC is stored in a battery than battery terminal should change between positive and negative 50 times a second. Battery cannot change its terminal with such rapid speed. This is the main reason why AC cannot be stored in a battery.
Furthermore if we connect AC to battery than it will charge during positive cycle and discharge during negative cycle. Positive cycle cancels negative cycle, so average voltage or current will be zero.

40: What is electrical machine?
A device which is used for electro-mechanical conversion or vice versa is called electrical machine. If it is converting from mechanical to Electrical than it is called generator. If Elec-Mech than motor.