• Four-wire Kelvin measurement cancels test lead resistance for 0.25 percent basic accuracy
• Measures 5 micro-ohms to 400 ohms across six ranges, resolution down to 1 micro-ohm
• Selectable test currents: 10 mA, 100 mA, 1 A, and 10 A (nominal 10.2 mA, 102 mA, 1.02 A, 10.2 A)
• Front-panel polarity reversal with averaging to cancel undesirable voltages
• Stores up to 99 test results; automatic storage of multiple results
• Automatic discharge of residual charge on the equipment under test
• Thermal switch protects the 10 A range in continuous use; input fuse protection
• Built-in rechargeable NiMH battery pack, up to 850 tests at 10 A per charge
• Large multi-function backlit LCD; sealed case rated IP64 (cover closed), IP53 (cover open)
• Included DataView software for download, temperature compensation, and reporting

• Bonding and joint resistance: mechanical bond tests, aircraft and rail bonds, metallic coating resistance
• Contact resistance on circuit breakers, switches, and busbar and cable connections
• Ground bond and continuity verification
• Resistance measurements on motor and transformer windings

Cable and component resistance checks for quality control and maintenance

• Type: portable micro-ohmmeter, four-wire Kelvin method (de-energized circuits only)
• Resistance range: 5 micro-ohms to 400 ohms, six ranges
• Resolution: 1 micro-ohm (best), stepping to 10 mohms and 100 mohms on upper ranges
• Basic accuracy: plus or minus (0.25 percent of reading + 2 counts)
• Test current: 10.2 A, 1.02 A, 102 mA, 10.2 mA (all plus or minus 2 percent); 10 A guaranteed on the lowest range
• Open circuit voltage: 4 to 6 V; max inductance: 0.5 H
• Voltage indication: 0.01 mV to 4.70 V; current indication: 5.0 mA to 11.00 A
• Memory: 99 test results, with DataView software (included)
• Power: rechargeable NiMH 6 V, 8.5 Ah pack, built-in 90 to 256 V (45 to 420 Hz) charger
• Battery life: about 850 tests at 10 A, up to 5000 at 10 mA (5 s on / 25 s off duty cycle)
• Output fuse: 12.5 A, 500 V, 6 x 32 mm
• Dimensions: 10.70 x 9.76 x 7.18 in (272 x 248 x 182 mm); weight 10 lbs (about 4.5 kg)
• Case protection: ABS polycarbonate, IP64 cover closed, IP53 cover open
• Operating temperature: 14 to 131 F (-10 to 55 C), 10 to 85 percent RH; altitude below 2000 m
• Safety: IEC/EN 61010-1, Measurement CAT III 50 V with respect to earth, Pollution Degree 2

The AEMC 6240 answers a simple question on switchgear, motors, and bonded joints: is this connection good, in real numbers. Built around the four-wire Kelvin method, it cancels test lead resistance so the reading reflects the sample, not your leads, with 0.25 percent basic accuracy. It measures from 5 micro-ohms to 400 ohms across six ranges, resolves down to 1 micro-ohm, and lets you pick the test current (10 mA, 100 mA, 1 A, or 10 A) to match the sample.

The unit is packaged in a sealed, safety-yellow field case (IP64 with the cover closed, IP53 open) and runs on a built-in rechargeable NiMH pack, so it goes where the work is. A front-panel polarity reversal function averages readings to cancel stray voltages, up to 99 results store to memory, and a thermal switch protects the 10 A range during continuous use. Input fuse protection and automatic discharge of residual charge on the sample keep the operator and the instrument safe. Note that the 6240 tests de-energized circuits only.

Included DataView software lets you download results, apply temperature compensation, and generate reports for acceptance and maintenance records.