What is the rated output of a current transformer (CT)?

The rated output of a current transformer (CT) is typically standardized, and 5A is one of the most common outputs used in practical applications. Current transformers are designed to produce a reduced current in their secondary circuit proportional to the primary current being measured. This allows for safe measurement and monitoring of high currents within electrical systems.

The 5A output allows for easy integration with standard metering equipment and provides a balance between manageable levels for measurement devices and sufficient sensitivity for monitoring larger currents effectively. Most measurement equipment, such as ammeters and protective relays, are calibrated to work with a 5A output from current transformers, which is why this option is the most widely adopted in the industry.

While other outputs like 1A, 2A, or 10A can exist, they are less common in standard applications, making 5A the primary choice for many electrical installations. Understanding this helps clarify why the other options are less relevant in typical scenarios.