Low Voltage Current Transformers

A current transformer (CT) is an instrument transformer that produces a reduced current in its secondary winding proportional to the current flowing in its primary. CTs are used to safely measure high currents for metering, protection, and control in power systems.

The CT ratio depends on your application's maximum expected current. Common ratios include 100:5, 200:5, 400:5, and 600:5 for metering, and higher ratios for protection applications. Contact our engineering team for help selecting the right ratio for your specific switchgear or motor control application.

Metering CTs are designed for high accuracy at normal operating currents (typically 0.3% or 0.6% accuracy class). Protection CTs are designed to maintain accuracy during fault conditions at much higher currents. Many of our models serve both metering and protection applications.

The window size must accommodate your primary conductor (bus bar or cable). Our toroidal CTs range from 1.00" to 8.25" diameter windows, and rectangular split core CTs offer alternative form factors for larger conductors. Measure your conductor and select a CT with a window that provides adequate clearance.

Yes. Our current transformers are UL Recognized and CSA certified, meeting IEEE C57.13, CSA 66.1-06, and CSA 66.2-06 standards. All products are manufactured in our ISO 9001:2015 certified facility in Bartlett, Illinois.