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basic application of current transformers are : |
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Lowering the very high primary current passing through bus
bars, cables, or wires to 5A or 1A. A
measurable quantity by measuring instruments.
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Isolating the measuring instrument and protective devices
from mains.
- Reproduces
proportionate primary current on its secondary side required
for extending the range of the instruments.
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Basically
CTS are of different types :
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- BAR
PRIMARY CURRENT TRANSFORMER (BPCT)
For Current of 100A and above the bus bars or cables are
quite thick and it is easier to measure the currents without
breaking the bus bars or cable by means of Bar Primary current
transformer which can be slipped over the bus bar or cable.
These CTs are most commonly used as they are study compact
and cheaper.
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- WOUND
PRIMARY CURRENT TRANSFORMER (WPCT)
For current below 100A, it is uneconomical to achieve the
desired accuracy by making CT Bar primary type and the solution
is Wound Primary C.T., where both primary and secondary
are Wound over the core.
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- PORTABLE
CURRENT TRANSFORMERS (PCT)
They are Bar primary type above 100A primary current and
for lower ranges it is wound primary type. These C.T's are
used where precision measurements are required like in Laboratories
and precision and control rooms.
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