RMS clamp meter

GMC-I PROSyS has introduced the CP41 AC/DC True RMS Clamp Meter, , a hand-held unit that combines simplicity of operation and convenience with non-invasive measurement of current to an accuracy of ± 1% of reading and resolution of 1mA.

The CP41 meets the needs of a wide range of users in industrial and automotive markets. Its range and sensitivity allow measurement of operating currents, and leakage currents, with a single product, and without breaking connections in the circuits under test. Measurement capability in the mA range permits verification of 4-20mA current-loops in process-control systems, while the meter is equally applicable to testing light-industrial and residential electrical installations.

It measures, selectably, DC or AC currents with a resolution of 1mA and, on its AC ranges, with true-RMS current indication. It maintains accuracy even in electrically noisy environments, featuring excellent rejection of external magnetic fields together with a very high level of immunity to interference from voltage transients. The meter is battery-powered, and has a 4-digit liquid-crystal display: full-scale readings are up to 4A or 40A, with auto-ranging and auto-zero functions. The company also offers a second variant of the CP41, the CP410, which measures higher currents: its auto-range full-scale limits are up to 40A or 400A.

The unit uses compensated Hall-Effect sensing in a patented magnetic circuit, to detect the magnetic current generated by the current of interest; this technology allows measurement of both DC and AC currents. AC currents are measured over a frequency range of 15 to 400 Hz.

In operation, the user opens the jaws of the probe, which have a 25-mm aperture, and closes them around the conductor carrying the current of interest: advanced design of the magnetic circuit means that location of the conductor within the aperture is non-critical and errors due to off-centre positioning are negligible. The CP41’s design supports safe, single-handed operation in hazardous areas, assisted by a display-hold function which allows the user to take a measurement in a difficult-to-reach location, remove the CP41 from the test site, and to bring it back into clear view still displaying its current reading.

Both instruments meet the Safety requirements of EN61010-2-032:2002 and the EMC specifications of EN 61326-2-2:2006, and provide safe operation on uninsulated conductors carrying voltage of up to 300V with respect to ground. They measure 194 x 74 x 25mm, weigh 235g, and operate for 15 hours from a standard 9V alkaline battery.