Answer / nageswara rao

line pt means measure incoming line voltage and protect line
under voltage protection 88% of voltage,bus pt means measure
out going bus voltage and protect bus under voltage
protection for motor feeders,44% with time delay 3-5 sec,
pt means the potential transformer, which is used as a
instrument transformer in measuring device. its main use is
to step down the voltage at measurment levels.

Answer / logachandran m

We are using Both Line& Bus PT(Potential Transformer) But different application.
1. Line PT- This PT using on main Incomers to Bus bar system or Main out going from Bus system,it will protect the particular feeder system. Ex,Transformer incomers,Generator incomer,etc,....
2. Bus PT- This PT using on Particular Bus bar system, It will protect the Bus Bar. Its will useful for Bus bar to bus bar synchronization or Bus bar to any source(Using with line PT)

Answer / v.doraiswamy

Line PT:The Line PT is located on line side of the Feeder.
This will have normally has two secondary cores.The core
with accuracy cl.1 is used for metering purpose(ie)
measuring Voltage,watt,var etc. Core with accuracy cl.3P is
used for Porotection like distance scheme relay,
directional O/C,E/F relay. Also metering secodary core is
used synchronising the line with Bus.

Bus PT : The Bus PT functions are same as Line PT. But This
is located on the main Bus and this can be used for all the
circuits being located in the Bus. For cost point of view
it better to have common Bus pt for all the circuits.

Answer / pardeep bathinda

1 Bus pt use for under / over voltage protection and measure for volt and synchronization time use for voltage matching
2 line pt use for income line voltage and protection line under and over voltage

Answer / k.prakashchandra

In SS bus PT is used for metering and protection.For line
generally CVT is employed for PLCC and "live line" indication

Answer / satale kiran

pt means the potential transformer, which is used as a
instrument transformer in measuring device. its main use is
to step down the voltage at measurment levels.

Answer / dipankar chatterjee

Line PT monitor the healthiness of line feeders. O/v, U/v, Underfluxing and overfluxing, Trip ckt supervision, Directional overcurrent etc apart from distance protection and voltage for auxiliary relays. Bus PT is preferred for double bus system to have synchro check and bus voltage. Fault in line PT can shutdown the line feeder only but Bus PT fault will Trip all outgoing feeders. Preferably, Transformer feeders should have line PT only if single incomer with multiple outgoing feeders in 132 kV system.

Answer / d chatterjee

Line PT is serving the purpose of any control voltage requirements for the system with single incomer feeder but Bus PT is required for more than one incomer for synchro check and Bus differential protection.

Answer / ramji

Line PT has metering and Protection Cores. Its main use is
to mointor the Line Voltage parameters and is widely used
in protecting Lines in case of Faults occuring due to Phase
to phase faults and phase to earth faults which comes under
its review.

sometimes it has a core for meeting synch with respect
others incase the line breaker opens

Bus pt has metering core and protection core for BUS BAR
protn which mointors the faults in all the buses with
respect to that in a particular substation only

Answer / vels

the sensitivity of voltage drop of line PT during the line
fault condition is high than a bus PT

vels

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