Using Current Transformer In Core Saturating Mode Enables DC Current Measurements
by Viktor Vogman, Power Conversion Consulting, Olympia, Wash., How2Power Today, Oct 14 2022
Focus:
Current transformers (CTs) are among the most effective isolated current sensors and can
measure up to thousands of amperes. Besides providing immunity to common-mode noise and
low power dissipation, a CT does not require separate converters supplying
isolated dc voltage to power up the sensor input circuitry. Normally, CT-based current
sensors are only intended for monitoring of ac or pulsing currents with zero minimum
levels. However, utilizing the transformer’s saturation mode and a special technique for
detection of the dc component can expand CT-based sensor usage to enable dc current
monitoring. This article studies an opportunity for adopting such a technique and presents
design considerations for CT-based dc current monitoring.
What you’ll learn:
- How to measure dc current using a current transformer operating in saturation mode
- How to measure a dc current applied to a current transformer’s primary by applying a sawtooth waveform on the secondary and detecting demagnetization of the core
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