New current transformer offers IEC 60044-1 accuracy of 0.2 percent

February 25, 2013 // By Paul Buckley
REO’s new AC current transformer, which is accurate to 0.2%  and meets IEC 60044-1 requirements, can used to isolate low voltage monitoring circuits from higher power circuits when monitoring or measurement must take place.

A current transformer, which produces a reduced current accurately proportional to the current in the circuit, can be connected to measuring and recording instruments and are commonly used in metering and protective relays in the electrical power industry. Historically only AC waveforms could be monitored, but now, thanks to conditioning electronics, DC and complex waveforms can also be measured accurately, usually as feedback for equipment and systems. This regulates output with respect to some dynamic characteristic, for example, the resistance of a load that changes as it heats up.

The device is ideal for military applications such as monitoring a torpedo motor’s speed is using current transformers by one European manufacturer, to ensure that the torpedo is speedily and accurately targeted. Another application is servo motor current for automated turret stabilisation and automated aiming on tanks. The objective is to ensure that the tank can fire accurately regardless of the speed and terrain upon which it is travelling. Key to this system is the monitoring of current in the servo motors to provide linear and accurate feedback.

REO’s range is competitively priced with electrical and physical characteristics that allow the products to be used as drop-in replacements in applications where competitors’ devices are being used. REO also offers bespoke electrical characteristics and physical form, fixings and connections. For example, REO owns a patent on a design which provides accurate and repeatable readings, no matter where the conductor passes through the aperture.

The standard designs utilize automatically wound cores, housed within encapsulated housings to ensure robust mounting and protection from physical and environmental shock and vibration. These designs allow fast and straightforward mounting for control panels and industrial equipment, but also ensure consistent and reliable operation at pressures and temperatures which exceed that of normal electrical components.

The magnitude of current is typically up to 3000 A at a frequency response from DC to 150 kHz. REO also produces differential current