CT 600/5-40

A CT 600/5-40 is a Current Transformer (CT) used to measure and monitor high electrical currents safely in power distribution systems.

Here's what the designation means:

600/5 – Converts a primary current of up to 600A into a standard 5A secondary current for measuring instruments and protection relays.

40 – Refers to the approximate 40 mm window (inner diameter) through which the conductor or busbar passes.


Uses of a CT 600/5-40

Measures high current without connecting meters directly to high-current conductors.

Supplies current to ammeters, energy meters, and power analyzers.

Provides input to protective relays for overload and fault protection.

Used for energy monitoring, load management, and power quality analysis.

Electrically isolates measuring equipment from high-voltage/high-current circuits, improving safety.


Common applications

Electrical distribution panels

Industrial switchboards

Motor control centres (MCCs)

Generator panels

Transformer panels

Commercial and industrial power monitoring systems


For example, if 480A flows through the primary conductor, the CT outputs 4A on its secondary side (since the ratio is 600:5), allowing standard measuring devices to read the current safely and accurately.