Question
Download Solution PDFGiven a 250 : 5 current transformer used with an ammeter reading of 2.7 A, what is the line current (primary current) in the circuit?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe correct option is 2
Concept:
In high voltage A.C. circuits, the measurement cannot be done by using the method of extension of ranges of low range meters by providing suitable shunts.
In such conditions, specially constructed accurate ratio transformers are used. These transformers are used to isolate the instruments from high current and high voltage A.C. circuits.
These are generally classified as
(i) Current transformer - large alternating currents can be measured
(ii) Potential transformer - High voltages can be measured.
Note: The secondary CT or PT is connected to the low-range meter.
Application:
Given, CT ratio = 250/5 = 50
Measured value = 2.7 A
Hence, estimated line current = measured value × CT ratio
Line current = 2.7 × 50 = 135 A
Last updated on May 29, 2025
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