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CAGE Code: 5DME2
ITAR Registration Code: M28889

- March 24th 2017 -
Call: 1 (800) 377-3244
We Are Open Monday-Friday 8 am - 5 pm PT

Read This First; Contains Basic Information on each types of Current Transformers offered by CWS

Current Transformers are divided into 2 categories:- High Frequency Current Sense Transformers and Line Frequency Current Transformers. The High Frequency Current Sense Transformers are used in switching mode power supplies (SMPS) application, usually to detect and measure the current for the feedback control circuitry. These Current Transformers are designed using manganese zinc ferrite cores and the frequency of operation is 20Khz up to 1000 Khz. The Line Frequency Current Transformers are mainly used in precision instrumentation and amperes measuring devices for the 15 Hz to 200 Hz range. These Current Transformers are designed using tape wound cores due to the lower frequency of operation. The tape core materials used for these current transformers are various iron and nickel alloys, permalloy,amorphous, nanocrystalline, etc.

Current Transformers are therefore used to measure current for power management and controls, applications in safety protection and in current limiting. Current Transformer uses a single turn primary. The primary winding is not built into the transformer itself. It has an opening or hole for the primary wire to go through. The number of secondary turns determines the current ratio.

The CT Series is for 15Hz to 50Hz/60 Hz to 200 Hz line frequency current sensing applications. It has an accuracy class of 0.5% to 5%. Typically uses are in watt meter, electricity dispensers, power calibrators, power transducers, precision power meters, digital meters for power systems and server motors. In some applications, a DC current maybe present in the power line where the AC currents needs to be measured. The CT-100X DC Tolerant Current Transformers are designed to handle such an application. The data sheet in pdf for this series will show the amount of DC current it can handle without saturation

The 72-000, 72-100, 72-200, 72-300, 72-400 and 72-500 series current sense transformer are mainly used in 20 Khz and above in a switch mode power supply. The secondary inductance shown in our specification data is measured at the given voltage level ( the test voltage freq. is set at 15.75 Khz) shown at the right of the inductance value.

The terminating resistor is also called the "burden resistor", and it is the resistor across the secondary terminals. The voltage across the terminating resistor is equal to Terminating Resistor divided by Number of secondary turns. This is the voltage that is being measured by the engineer for current monitoring purposes.

The primary Unipolar rating refers to single ended wave forms ( swing from zero to positive) such as in forward topology, etc. Primary bipolar primary waveform refers to double ended topology ( swing from positive to negative). These ratings are in Amperes-microseconds, and it is the maximum at which the transformer core will not saturate. Amp-microsec is the current flowing through the primary multiply by the ON time. The peak primary current these transformer can handle is up to 35 Amps.

Disclaimer: Coil Winding Specialist, Inc., its affiliates, agents, and employees acting on behalf of Coil Winding Specialist, Inc. (collectively, CWS) disclaim any and all liability for any errors, inaccuracies or incompleteness contained herein or in any other disclosure relating to any product. CWS reserves the right at any time and from time to time to make changes to design, technical specification, or construction of any product listed on this website without notice. CWS also reserves the right to discontinue or limit sale of any product or service available throughout this website on temporary or permanently basis without notice. CWS highly recommends customers not to use its products offered on this website for inappropriate use and applications. Products should be tested for its suitability by prospective customers in all possible applications and conditions. Customers using or selling CWS products for use in other than recommended applications do so entirely at their own risk and agree to fully indemnify CWS from any damages arising or resulting from such use or sale.

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CWS 353 West Grove Ave. Orange, California 92865
Call us Toll Free: 1-800-679-3184 or 1 (800) 377-3244

Tel: (714) 279-9010, Fax: (714) 279-9482

Copyright 2008, Coil Winding Specialist, Inc
Updated July, 2013

CAGE Code: 5DME2(Registered with