Transformers used for metering installations are commonly known as what type of transformers?

Transformers used for metering installations are commonly referred to as instrument transformers. This designation specifically applies to transformers that are designed to measure electrical values such as current and voltage in a way that is safe and practical for metering and relay protection purposes.

Instrument transformers serve two main types: current transformers (CTs) and voltage transformers (VTs). These devices step down high currents and voltages to lower, manageable levels that can be easily read by measurement devices, while also providing isolation for safety. They allow for accurate monitoring and management of electrical systems, which is essential in ensuring the correct functioning of metering equipment.

In contrast, power transformers are used for stepping up or down voltages on transmission systems for efficiency in power distribution, while distribution transformers are utilized to lower voltage for consumer use. Isolation transformers, on the other hand, provide electrical separation for equipment safety and noise reduction, not specifically for metering purposes. Thus, the specificity of instrument transformers in their dedicated role for metering is what makes this choice the correct answer.