Amgis Toroidal Power Products

50/60Hz Current Transformers and Current Sensors

Current transformers (CTs), often called instrument transformers, are used for measurement of electrical currents. A current transformer produces a reduced current accurately proportional to the current in the circuit (1/N x I), which can be conveniently connected to measuring and recording instruments.

50/60Hz current transformers

One of the major benefits in using current transformers in your application is the isolation it provides between the circuit and the measuring equipment; typically, to measure the current, a break in the circuit would be needed to connect the ammeter in series, a CT can be placed at any location on a board without affecting the connectivity of the circuit.

Current transformers represent a unique application of transformer theory. Unlike power transformers, their purpose is not to change the line voltage up or down to power a piece of equipment. Rather, their purpose is to measure the amount of current passing through a conductor and to isolate this measurement from the source.

Whether utilizing a standard EI core or a toroidal core, current transformers generally employ a single turn primary winding and a multi turn secondary winding. Typical turn ratios are 1 to 500 or 1 to 1000 indicating that the actual current flowing through the primary winding can be reduced by a factor of 500 or 1000. This makes it practical to measure very large currents in a safe and efficient manner.

Current sensors, primarily used in sensing applications, function as the secondary of a current transformer. The conductor carrying the current to be measured is the “one turn primary.”

Applications of current transformers and current sensors include:

  • Metering
  • Coupling Analog to Digital Circuits
  • Sensing Overload Current
  • Ground fault detection
  • Load drop or shutdown

Amgis offers several lines of standard 50/60Hz toroidal current transformers: low cost CT series, high output voltage CX series, high accuracy CCX series, and precise/very high accuracy CP series. We currently offer one line of current sensors: ASM series.

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