Current Sense Transformers & Sensors

Current transformers accurately sense and measure current flow in power supply circuits in a non-invasive way. Ideally, they shunt a very small sample of the current to measure while dissipating minimal energy. The sensed current information is typically used to prevent overcurrent conditions and to monitor and control circuits in power supplies and other powered applications. Current sensors are frequently used to measure and control the load current in power supplies, safety circuits and a variety of control circuits. In applications where controlling the current is required, such as in power supplies, accurately sensing the magnitude of the current is a fundamental requirement. Coilcraft manufactures wire-through-hole current sensors and SM current sense transformers for measuring current at frequencies from 50/60 Hz to greater than 1 MHz.

Selecting the appropriate current sense transformer for your application begins by determining:

The maximum current to be sensed
The frequency of the current waveform to be sensed
The duty cycle of the current waveform to be sensed
The desired output voltage across your terminating resistor

Selection is greatly simplified with our Current Transformer Selector tool. This online resource helps you quickly find the best current transformer for your application and includes behind-the-scenes flux density calculations to assure your selection is sized correctly. Our Selecting Current Sensors and Transformers application note discusses the technology and applications of current transformers.

Current Transformers

Current	Frequency range	Isolation voltage	Series
7 A max	11 kHz – 1000 kHz	500 Vrms	CST4835
20 A max	7 kHz – 1000 kHz	500 Vrms	CSTx
20 A max	10 kHz – 1000 kHz	500 Vrms	CST7030
20 A max	16 kHz – 1000 kHz	1000 Vrms	CU8965
28 A max	11 kHz – 1000 kHz	3000 Vrms	CST1211
30 A max	2 kHz – 1000 kHz	500 Vrms	SCS
35 A max	1/2/3 kHz – 1000 kHz	3750 Vrms	CS4xx0V
47 A max	1 kHz – 1000 kHz	1500 Vrms	CST2010
40 A max	1 kHz – 1000 kHz	2100 Vrms	CST2010V
40 A max	0.4 kHz – 1000 kHz	4000 Vrms	CST2020
88 A max	0.2 kHz – 1000 kHz	5000 Vrms	CST3015