Cropico ohmmeter solves aircraft-corrosion threat

Air-force technicians are using the Cropico DO4000 digital ohmmeter to measure the ground points on its fighter jets and Apache and Chinook.

These ground points are located at various key points around the airframe and the DO4000 enables technicians to quickly and easily check that the resistance levels between each one are lower than 2.5milliOhm.

Ground points are required to create a safe electrical network inside an aircraft - when it flies through dry air, it gets statically charged, so when it lands this needs to be safely discharged through the ground.

After that, the ground personnel can maintain the aircraft safely.

It is important that these ground points have specific standards because, for example, when refuelling the aircraft there could be spark-ignition due to residual charge.

Also the ground points take care of the different currents running throughout the airframe during flight.

Total Test and Measurement Support, Cropico's Netherlands test and measurement-equipment distributors, supplied the DO4000.

The DO4000 ensures measurement accuracy, including forward and reverse current measurement with auto averaging, true current zero, long-scale length and a selectable measurement range from 40mW to 4kW with respective resolutions between 10mW and 1W.

Within the range, model 4001 also includes temperature compensation, with pre-set coefficients for copper and aluminium, plus user-settable coefficients for other materials.

Temperature measurement is available for the -50 to +800C range.

Protection up to 415Vrms is provided at the measurement terminals and push-button operation is achieved easily by clearly marked function controls.

Direct reading measured values are displayed on a four-digit LCD display.

Over range and low battery indication is also provided, and warning LEDs illuminate when an open circuit lead condition is detected.