Surface mount isolated current transducers have an integrated current conductor
PCIM Europe 2017: LEM introduces the GO series, expanding its miniature, IC transducers range for AC and DC isolated current measurement up to 300kHz.
The transducers offer full isolation, despite their small size, says the company, by integrating the primary conductor for nominal current measurements of 4.0, 6.0, 8.0, 10, 12, 16, 20 or 30A with a measurement span of 2.5 times the nominal current. The transducers are able to support high overload currents up to 200A peak for one millisecond, similar to the response time of a transducer with a magnetic circuit, says the company.
The transducers are mounted directly onto a PCB and are available as small form factor SO8 or SO16 surface mount devices. This says the company, reduces manufacturing costs and save space in space-constrained applications.
The IC transducers integrate low resistance primary conductors (minimising power losses) within a proprietary ASIC, to allow direct current measurement and consistent insulation performance, while still providing high creepage and clearance distances.
Standard models provide an analogue voltage output with different sensitivity levels, according to the models, to achieve an output voltage of 800mV at IPN for 5.0V versions and 500mV at IPN for 3.3V versions. Ratiometric output is an option though dedicated models.
The transducers are designed with primary integrated conductors for gradient measurement, to provide immunity against the external fields found in power electronic applications.
The design combines field-proven techniques such as spinning, programmable internal temperature compensation, via the EEPROM, for accuracy over the full range of temperature, from -40 to +125°C with a maximum of 3.74%. The absence of a magnetic circuit means that there is zero magnetic offset generated.
The SO16 package, provides two different over-current detection (OCD) warning levels as a standard on two dedicated pins; one very fast, and the other slower, but more accurate.
Some applications, particularly for motor drives, need speed but are less demanding of the current range and isolation levels while having strong pressure on price and dimensions. Examples of this are white goods, window shutters and air-conditioning, where the low cost and small size of these transducers are beneficial. In these applications using AC drives, AC and DC inverters, supplies, servo-drives, the transducers compete against other traditional low cost current measurement solutions such as shunts, commonly used for cost reasons, but add the benefit of natural insulation.
The GO series conforms to latest industrial standards, and is covered by the company’s five-year warranty.