Instrument transformers include CTs and VTs for measurement and protection. Which statement best describes their purpose?

Instrument transformers include CTs and VTs for measurement and protection. Which statement best describes their purpose?

• A. Voltage amplification
• B. Measurement and protection
• C. Protection and isolation only
• D. Voltage regulation

Answer: (B)

Instrument transformers are used to make high-power quantities safe and practical to measure and to protect equipment. Current transformers take the large line current and produce a proportional, lower-current output that meters and protective relays can handle, while keeping electrical isolation between the high-power circuit and the measuring devices. Voltage transformers do the same for voltage, stepping down a high line voltage to a lower, standardized level for measurement and protection circuits. The key purpose is to enable accurate measurement and reliable fault protection without exposing meters or relays to dangerous voltages or currents. They provide the scaled signals that protection relays use to detect faults and decide when to trip, and they allow meters to read system values correctly. They’re not intended to amplify voltage or regulate it; isolation is a beneficial side effect, but the main role is measurement and protection.

Instrument transformers are used to make high-power quantities safe and practical to measure and to protect equipment. Current transformers take the large line current and produce a proportional, lower-current output that meters and protective relays can handle, while keeping electrical isolation between the high-power circuit and the measuring devices. Voltage transformers do the same for voltage, stepping down a high line voltage to a lower, standardized level for measurement and protection circuits.

The key purpose is to enable accurate measurement and reliable fault protection without exposing meters or relays to dangerous voltages or currents. They provide the scaled signals that protection relays use to detect faults and decide when to trip, and they allow meters to read system values correctly. They’re not intended to amplify voltage or regulate it; isolation is a beneficial side effect, but the main role is measurement and protection.