ASIC-based current transducers extend range to 250A
PCIM 2014: Three HO series open-loop, Hall-effect ASIC-based current transducers have been released by LEM. They have a wide operating range of -40 to +105̊C. Stéphane Rollier says that the transducers are the only ones in the industry to offer over-current protection. The versatile devices offer a range of mounting options, PCB, panel or bus bar, and exploiting the aperture which measures 15 x 8mm, for cables and clamps.
There are three interchangeable mounts for the HO xxx-S panel mounted current transducers: one vertically, one horizontally and one on the busbar when used. The mount can be changed by the user for additional versatility.
The transducers measure DC, AC, and pulsed signals using the second generation of Open-loop Hall-effect ASIC, first introduced with the HO 8, 15, 25-NP and -NSM series and the HO 6, 10 and 25-P models.
Offset and gain drifts are up to twice as accurate across the temperature range, says the company, as the previous generation and have a faster response time of 2.5 to 3.5µs.
Operating from a single supply voltage of 3.3 or 5V, the transducers can measure up to x 2.5 the primary nominal current and integrate an additional pin which provides over-current detection set at x 2.93 the nominal current I PN (peak value). They also provide fault reporting in the event of memory corruption.
High clearance and creepage distances of more than 8mm and a Comparative Tracking Index (CTI) of 600 mean that, despite small packages of 229.5 to 331.5cm3, there is no compromise on the insulation level provided between the primary and measurement circuits.
Typically, the standard scaled analogue voltage output is converted into a digital value by an ADC which requires a reference voltage provided by the company. The transducer can also be configured to take measurements relative to an external reference voltage.
Applications include solar combiner boxes and solar-power inverters, as well as small smart meters, variable speed drives, uninterruptible and switch-mode power supplies, air conditioning, home appliances, static converters for DC motor drives, and robotics. The wide operating temperature range of -40 to +105°C also makes the transducers suitable for industrial applications.