LEM shrinks current transducers

Test & Measurement

15 April 2009 Test & Measurement

LEM has introduced several ranges of PCB-mounted current transducers housed in a package 30% smaller than the company’s LTS devices.

The CAS, CASR and CKSR family of transducers are intended for AC and DC isolated current measurement from 6 to 50 ARMS nominal, up to three times these nominal values for peak measurement and up to 300 kHz ±3 dB bandwidth. All models (6 ARMS, 15 A_RMS, 25 A_RMS and 50 A_RMS) are housed in the same compact package and can be set up on a printed circuit board according to the needs for different ranges from 1,5 A_RMS to 50 A_RMS, according to the model.

The new transducers have been specially designed to respond to the technology advances in drives and inverters, which require better performance in areas such as common-mode influence, thermal drifts, response time, levels of insulation and size. In these respects, the new models offer maximum thermal offset drift from 7 to 30 ppm/K and response time lower than 0,3 microseconds.

To obtain these performance levels, closed loop fluxgate technology was used, which enabled LEM to combine high accuracy and attractive price without compromising on attributes such as size, dynamic performance and wide measuring range.

Although the new transducers are 30% smaller than the existing LTS family, their insulation performance allows use in industrial applications without special PCB layouts. The CKSR model has one more primary pin than the three pins of the CAS and CASR models and a different primary footprint enabling higher creepage and clearance distances of 8,2 mm to be achieved. This is particularly useful when higher insulation is required in applications with high working voltages such as 600 V_RMS according to the EN 50178 standard. Moreover, this additional primary pin allows a configuration of the CKSR 6-NP model for a nominal current range of 1,5 A_RMS.

All transducer models are designed for direct mounting onto a printed circuit board for primary and secondary connections, and all operate from a single 5 V supply. The CASR and CKSR models provide their internal reference voltage to a V_REF pin; an external voltage reference between 0 and 4 V can also be applied to this pin.

The transducers are suitable for industrial applications such as variable speed drives, UPS, SMPS, airconditioning, home appliances, solar inverters and also precision systems such as servo drives for wafer production and high-accuracy robots.

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LEM shrinks current transducers

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