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.
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:
- 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.