Transformer ratios of 400:1 are typically used in instrument transformers. Which type of transformer is described?

Transformer ratios of 400:1 are typically used in instrument transformers. Which type of transformer is described?

• A. Instrument
• B. Potential
• C. Current
• D. Distribution

Answer: (A)

Instrument transformers are built to scale down high voltages or currents so meters and protective relays can read them safely and accurately. A large turn ratio like 400:1 is a typical step-down used in measurement devices, producing a low, manageable signal for instrumentation without drawing much power. This fits the purpose of instrument transformers, which cover both potential transformers (voltage measurement) and current transformers (current measurement). Distribution transformers, by contrast, are designed to deliver power to loads, so their ratios are chosen more for matching system voltages and load needs than for providing standardized measurement signals.

Instrument transformers are built to scale down high voltages or currents so meters and protective relays can read them safely and accurately. A large turn ratio like 400:1 is a typical step-down used in measurement devices, producing a low, manageable signal for instrumentation without drawing much power. This fits the purpose of instrument transformers, which cover both potential transformers (voltage measurement) and current transformers (current measurement). Distribution transformers, by contrast, are designed to deliver power to loads, so their ratios are chosen more for matching system voltages and load needs than for providing standardized measurement signals.