Current transducers measure to 25A, in PCB-mount format

April 08, 2014 // By Graham Prophet
LEM has added to its range a series of open-loop Hall-effect ASIC based devices measuring up to 25A DC, AC or pulsed; with over-current detection and fault reporting functions, they operate over -40 to +105ºC and have a PCB-mount design with aperture for the primary conductor.

In the HO series of PCB-through-hole mounting current transducers, these units provide an aperture of 8 x 8 mm to carry the primary conductor under measurement, extending the options for this form-factor. The new models, for 6, 10 or 25 A nominal measurements of DC, AC, and pulsed signals use LEM’s latest Open-loop Hall-effect ASIC introduced with the launch of the HO 8, 15 and 25-NP & –NSM models.

The HO 6, 10 and 25-P models’ offset and gain drift are twice as accurate (over the temperature range -25 to +85ºC) as the previous generation. A high level of insulation between primary and measurement circuits, due to the high clearance and creepage distances of more than 8mm and a CTI (comparative tracking index) of 600, allows a test isolation voltage of 4.3 kVRMS/50 Hz/1 min.

HO xx-P series transducers increase performance in other areas such as response time, power supply and noise, allowing the development of more technically advanced power electronics applications.

The transducers require a PCB mounting area of 2.88cm 2 and weigh 10g. They can measure up to 2.5 times the primary nominal current but also incorporate an additional pin providing an over-current detection set at 2.63 x the nominal current I PN (peak value). The products also provide fault reporting in the case of memory contents being corrupted. LEM's HO xx-P transducers operate from a single supply voltage at 3.3 or 5V.

The new range delivers its output as a scaled analogue voltage; in most systems this will be converted to a digital value by an analogue/digital converter which requires a reference voltage. The HO xx-P series can also be configured to make measurements relative to an external reference.

The transducers are CE marked, conform to the EN 50178 standard and are recognised for industrial applications with a wide operating temperature range of -40 to +105°C. LEM offers a five-year warranty for each transducer.