Instrument Transformer Feature Matching

The question asks to match Instrument Transformers (CT and PT) with their specific operational features.

Current Transformer (CT) Analysis

Let's analyze the features associated with a Current Transformer (CT), represented by X:

• Feature Q: An open-circuited secondary is highly undesirable for a CT. If the secondary circuit is opened, the primary current (which is the line current) induces a very high voltage across the open secondary terminals, posing a safety hazard and potentially damaging the transformer.
• Feature R: The primary winding of a CT is connected in series with the line conductor to measure the line current. Therefore, the primary current is essentially the line current.
• Feature P (parallel connection) is characteristic of a PT.
• Feature S is related to the burden, but Q and R are more defining characteristics.

Thus, CT (X) matches features Q and R.

Potential Transformer (PT) Analysis

Now let's analyze the features associated with a Potential Transformer (PT), represented by Y:

• Feature P: A PT's primary winding is connected in parallel (across the voltage source) to measure the voltage.
• Feature S: The secondary burden (the load connected to the PT's secondary) affects the accuracy and the current drawn by the PT from the primary circuit. An increase in burden increases the secondary current, which, reflected to the primary, increases the primary current required to maintain the voltage ratio.
• Feature Q (open secondary danger) is primarily a concern for CTs.
• Feature R (primary current is the line current) describes CTs.

Thus, PT (Y) matches features P and S.

Final Matching Summary

Combining the analyses:

• CT (X) matches with Q and R.
• PT (Y) matches with P and S.

This establishes the correct matching as X with Q and R, and Y with P and S.