Power factor should be high in order to get smooth 
operation of the system.Low power factor means losses will  
be more

sorry i dont have the xat formula for that but 
 for ALUMINIUM CABLE:  1sq.mm = 1.2 A of current
      CU:              1sq.mm = 5.0 A of current
  and the relation b/w A & KW IS 
  1KW= 1000*A*240*COS#
   A- CURRENT
   240= VOLTAGE
   COS# = POWER FACTOR (.8 TO .99)
NOW IF U KNOW THE EXACT CURRENT LOAD OR LOAD IN THE FORM OF 
KW U CAN EASILY FIND THE AMPERE RATING.
AFTER FINDING THE AMPERE RATING U CAN CALCULATE THE THE 
SIZE OF THE CABLE.  ANKUSH MIGLANI 
                     9718151073
                  ankushmiglani2000@gmail.com

IT IS AN ELECTRONIC DEVICE USED TO CONVERT THE DATA OR 
INSTRUCTION INTO CODES AND TO RE USE D DATA DECODER IS USED 
TO OBTAIN THE DATA IN REAL FORM.
An encoder is a device used to change a signal (such as a 
bitstream) or data into a code. The code may serve any of a 
number of purposes such as compressing information for 
transmission or storage, encrypting or adding redundancies 
to the input code, or translating from one code to another. 
This is usually done by means of a programmed algorithm, 
especially if any part is digital, while most analog 
encoding is done with analog circuitry.

MCB - MINIATURE CIRCUIT BREAKER
MCCB - MODULE CASE CIRCUIT BREAKER
MCB RATING : 63 AMP (MAXIMUM) i.e. in the form of tpn( 
THREE PHASE + NUETRAL)
MCCB _ 63AMP (min.) 
MCB IS USED WHERE LOAD IS LOW BUT MCCB IS USED WHERE LOAD 
IS HIGH AND USE AS INCOMER.WHILE THE MCB IS USED FOR 
OUTGOING.
  
 Addition to the above answers :
Now a days MCB' are avialble till 125 Amps too.

Many of distribution board use MCB as as both incomer and 
out going. Normally recommended for   three phase input and 
single phaseout put , though  it is used for 3 phaseinput & 
out put.

Another important factor in MCB is it's breaking capacity 
is limited  up to 16 kA only though earlier it was limted 
up to 9 and 10 kA only.

MCB - MINIATURE CIRCUIT BREAKER
MCCB - MODULE CASE CIRCUIT BREAKER
MCB RATING : 63 AMP (MAXIMUM) i.e. in the form of tpn( 
THREE PHASE + NUETRAL)
MCCB _ 63AMP (min.) 
MCB IS USED WHERE LOAD IS LOW BUT MCCB IS USED WHERE LOAD 
IS HIGH AND USE AS INCOMER.WHILE THE MCB IS USED FOR 
OUTGOING.

MCB is miniature circuit breaker which is thermal oprated 
and use for short circuit protection in small current 
rating circuit. MCCB moulded case circuit breaker and is 
thermal operated for over load current and magnetic 
operation for instant trip in short circuit condition.under 
voltage and under frequency may be inbuilt. Normally it is 
used where normal current is more than 100A.

There are two types of exciters, static exciter and rotory 
exciter.purpose of excitor is to supply the excitation dc 
voltage to the fixed poles of generator.Rotory excitor is 
an additional small generator mounted on the shaft of main 
generator. if it is dc generator, it will supply dc to the 
rotory poles through slip ring and brushes( conventional 
alternator). if it is an ac excitor, out put of ac excitor 
is rectified by rotating diodes and supply dc to main fixed 
poles.ac excitor is the ac generator whose field winding 
are stationary and armature rotates. intial volatge is buit 
up by rsidual magnetisim.

exciter as per its name provides exitation to the 
generator. it gives the starting torque to the generator 
which helps in pre acceleration of the generator. 
 in case xciter is not there the excitation can be provided 
with the help of prime movers which are hand driven.
if need something else ask: ER. ANKUSH MIGLANI
                                   9718151073
                               ankushmiglani2000@gmail.com

As i know ,it is used to link the transmission of power 
between two power supply panels.The adopter can be Switched 
On/Off by using  Fuse swtch unit shortly called as FSU.

a bus pt can be used for synchronisation purposes as well

it is a potential transformer which is used for measuring 
and protection  of bus it is known as bus pt

U -means the voltage at that instance.
Uo-means the nominal voltage or design voltage.