LEM Introduces High-performance Split-core Current Transformers for Active Power Monitoring
LEM S.A. announced the TT series of compact split-core ac current transformers. These new devices feature an innovative core material, which enables the TT series to be the first to offer high performance at an attractive price. The core material used in the transformers is a new type of ferrite with improved magnetic permeability, allowing the accurate measurement of ac signals within an extended frequency range that includes 50/60Hz.
The new transformers feature an absolute accuracy better than 1% at the nominal current and even better for lower primary currents. The ferrite material provides an excellent linearity of better than 0.1%, even at very low levels, and the transformers have a particularly low phase shift of 1.5° ±1° between measured voltage and current. The hard and dense core allows very small air gaps and is insensitive to aging and temperature changes, in contrast to laminated FeSi or FeNi materials.
Two ranges of primary current measurement are available: 50A and 100A. The TT 50-SD measures only 1.43 x 1.69 x 1.24 inches (36.5 x 43 x 31.5 mm) with a .31 inch (8 mm) diameter sensing aperture for non-contact measurement. The TT 100-SD measures 1.75 x 2.00 x 1.44 inches (44.5 x 51 x 36.5 mm) with a .63 inch (16 mm) diameter sensing aperture. With a 3000:1 ratio, the TT 50-SD and TT 100-SD have low output currents (respectively below 16.66 mA or 33.33 mA). This, together with the internal output-protection circuit, guarantees safe and easy installation without the need to shut down operation, since there is no risk of producing a high voltage surge when the transformers are opened, unlike 1A or 5A output products.
Being small, safe, self-powered and split-core, the TT current transformers are easy to install and put into operation. They are well-suited for distributed measurement systems and can be retro-fitted into existing installations and non-interruptible equipment. Principal applications will be in the field of energy sub-metering and cost allocation, dynamic consumption and peak analysis, energy waste or defective equipment detection and power quality control.
