Tuesday, 7 December 2010

AC/DC current probes offer simple clamp operation and measurement down to 1mA

GMC-I PROSyS has extended its CP3 range of AC/DC, non-invasive, current measurement probes. Offering measurement sensitivity into the milliamp range, and with resolution of 1 mA, the CP3 range provides engineers with probes that are ideal for detecting and measuring leakage currents in automotive systems, or verifying correct operation in process control signal loops.

The CP3 range uses the clamp-on format; with one-handed operation, the user opens the jaws of the probe, closes it around the conductor carrying the current to be measured, and immediately gets a calibrated voltage output that directly represents the current to be measured. The CP3 probes use compensated Hall Effect technology to detect the magnetic field generated by the measured current, a technique that allows both AC and DC currents to be monitored by the same probe: when measuring AC, frequency response extends to 100 kHz.

GMC-I PROSyS has many years of experience in designing clamp-on current probes and the magnetic circuit employed in the CP3 range offers very high rejection of external magnetic fields, and very low errors due to off-centre positioning of the conductor within the measurement aperture. For the user, this means that the probe can easily be positioned in awkward, hard-to reach spaces and will return an accurate reading free from concerns about precisely orienting the unit or of the influence of nearby sources of interference such as large electric motors. Similarly, CP3 units offer high immunity to voltage transients (dV/dt rejection), further adding to their usability in electrically noisy environments.

A measurement challenge for today’s automotive engineers is to verify that vehicle systems have fully shut down when commanded to do so; this means measuring small currents in the main-battery connection of the vehicle without the disruption of breaking the connection to insert a conventional ammeter; the specification of the CP3 range meets this requirement exactly. In the same way, the
4 – 20mA calibrated signal current loops commonly used in process control installations can be checked without disrupting their operation. The probes will also detect small earth-leakage currents that indicate faults when carrying out electrical installation tests.

Features of the CP3 include automatic power-off to preserve battery life (which can be disabled for long measurement runs), and auto-zeroing. The probes can be ordered with measurement jaw apertures of 25 or 32 mm, and come in single or multi-range versions with full-scale measurement capability extending up to 300A.

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