two types of cables  LT and HT cables

3 types LT,BT,and HT cables

dry contact is that the contacts are floating. One example 
is the COM, NC and NO contacts of the relays. If no voltage 
is connected to them, it is called dry contacts.
Volt-free and dry contact mean the same thing. If a control 
system supplier offers a dry contact for you to read as a 
status bit, then he is offering to close a contact (relay 
or contact output) that is nothing more that a stand-alone 
set of contacts with no voltage, current, or anything else 
impressed across the contact set. It becomes the user's 
responsibility to determine how to sense that contact 
closure. Usually you do this by putting a voltage on one 
side and sensing the voltage on a return line from the 
other side of the contact when it closes. Once you apply 
voltage to the contacts, it becomes a wet contact. 
You "wet" the contact with a sensible voltage level.
.

COOLING IS THE MAIN ADVANTAGE TO MAINTAIN TEMPERATURE IN 
THE CABLE. LEAKE AND MAINTENANCE COST IS MORE.

in case of open circuit,voltage is equal to emf of cell but current is equal to zero

because for a current flow, the circuit should be closed 
otherwise there is no current flow takes place 
eg: battery.

wrong. 
 because for a current flow, the circuit should be closed 
otherwise there is no current flow takes place 
eg: battery.
 when the voltage source is open then there is no flow of 
current.
  if we connect a load to a battery then current flow takes 
place.

voltage like pressure...........
ex.take a water tank,in upper hole water comes slowley,
in under hole water comes very fast,because of that 
pressure,when current flows in high voltage u got a heavy 
shock,when current flows in low voltage u got a minor shock.
this answer is in my knwledge

wrong  flow of current depends on connected load.

LT voltage is upto 1 KV
HT voltage is upto 220KV.
EHT voltage is upto 1100KV.

LT voltage is upto 415 volts.
HT voltage is upto 220KV.
EHT voltage is upto 1100KV.

harmonics generated by nonlinear loads is presented

IT converts the pressure or Differential pressure into 4-
20mA DC and transmit the signal to the PLC

to reduced resistance of the path of Current flow so that 
the electrical equipment and all accessory can be save 
breaking the circuit.

TO MAINTAIN THE MAXIMUM LOW RESISTANCE (i.e, zero).

to make standby if neutral fail then the device get the 
neutral from the earthing.

submersible pump

subersible pump & 25 HP centrifugal pump are more suitable 
and economical for lifting water from 300 meter borewell.

25HP CENTRIFUGAL PUMP

25 HP CENTRIFUGAL PUMP IS ECONOMICAL FOR LIFTING WATER OF 
300Mtr BOREWELL.

when ever there are two units rotating at different speeds 
and they have to be coupled together while in rotation 
mode , then synchronisers are used to couple the two units 
at different speeds. 
A synchroniser first couples the units and the equalises 
the speed of both units thus making them as a single 
running unit. 
Synchronising in general means equalising.
Best example would be modern day automotive gear box - 
Synchromesh Gear Box. Olden days it was used on Fiat 
Padmini Cars and jeeps.

gear is a toothed wheel, which is used for transmit power

Gear is a power transmission device