# Current Transformer - Ratio Test

**URL:** <https://forumautomation.com/t/current-transformer-ratio-test/14210>\
**Category:** Electrical\
**Tags:** protection\
**Created:** [June 23, 2026, 10:04am UTC](https://forumautomation.com/t/current-transformer-ratio-test/14210 "2026-06-23T10:04:16Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [June 23, 2026, 10:04am UTC](https://forumautomation.com/t/current-transformer-ratio-test/14210/1 "2026-06-23T10:04:16Z")

</div>

### Current Transformer - Ratio Test

**[Current Transformer (CT) Ratio Test](https://forumelectrical.com/current-transformer-testing-and-validation-checklist/)** is a fundamental commissioning and maintenance test used to verify that the actual transformation ratio of a current transformer matches its rated ratio. The test ensures accurate current measurement and proper operation of protection relays, metering systems, and monitoring equipment.

 ![1](https://cdn.forumautomation.com/original/2X/b/bd8e4ebc34392c12648673eb6ec5aab6e1fbc596.jpeg)

Any deviation from the specified ratio can lead to measurement errors, incorrect relay operation, and reduced system reliability.