Rogowski coils employ loop, twist and click measures
Rogowski coils to be used as a sensor to measure current up to 300,000A AC with accuracy class 0.5 according to IEC 61869-10 and IEC 61869-6 are unveiled at SPS in Nuremberg, Germany, today by LEM.
The ARU range achieves IEC 61869-10 class 0.5 without the need for additional components such as resistors or potentiometers to calibrate the coil, which can drift over time, says LEM. The range benefits from Perfect Loop technology, a patented coil clasp that eliminates the inaccuracy caused by sensitivity to the position of the conductor inside the loop. This provides a robust and fast twist-and-click closure, adds LEM.
Compared with the company’s previous Rogowski coils (the ART range), the ARU range can be installed outdoors as the models comply with UV, water, dust and ice resistance standards. The range has a ruggedised material to be durable in extreme environments and is able to operate in a wide temperature range of -40 to +80 degrees C. An internal shield protects against external fields, improving accuracy and optimising performance for small current measurements, LEM continues.
The ARU series provides the same ease of installation as existing split-core current transformers, but with the benefits of being thinner and more flexible.
They are available in dimensions of 70, 125, 175, 250 and 300mm diameter for the aperture. Whichever dimension is selected, assures LEM, the ARU can be mounted very quickly by simply clipping on to the cable to be measured. Contact with the cable is not necessary, while the ARU models ensure a high level of safety as well as provide a high rated insulation voltage (1,000V Cat III PD2 – reinforced).
The ARU range allows the coil disconnection to be detected by a security seal passed through a specially designed slot, making it useful when used with a metering device. They can be used in applications requiring protection up to IP 68.
The models include an accuracy class 0.5 and complete the LEM product portfolio for the AC current measurement.
The ARU series current sensors are CE marked and conformed to the IEC 61869 standard series, as well as being covered by LEM’s five-year warranty.
