Portable 10A Low Resistance Tester for Electrical & Industrial Maintenance.

Measuring low resistance requires reliable test currents and clean connections. The AEMC Instruments 6240 Micro-Ohmmeter is a rugged, portable 10A tester built to measure contact resistance, motor windings, transformer coils, and ground bonds without complicated setups.

It uses a 4-wire Kelvin measurement method to eliminate lead resistance errors, delivering accurate readings down to 5 micro-ohms. With auto-start testing, built-in memory, and clear connection warnings, the AEMC 6240 speeds up routine maintenance and compliance testing in both field and factory environments.

Key Features

• 4-Wire Kelvin Measurement

  Eliminates test lead resistance so you get true, precise readings on low-resistance targets.

• 10A Test Current

  Delivers stable current up to 10A for testing heavy-duty switch contacts, busbars, and motor windings.

• Auto-Start Testing

  Automatically starts measuring as soon as proper contact is made, making repetitive production or field testing much faster.

• Connection & Lead Diagnostics

  Warns you immediately if test leads are loose, improperly connected, or affected by noise, preventing false data collection.

• Smart Power & Battery Management

  Internal rechargeable NiMH battery provides hundreds of tests per charge, with clear battery level indicators to prevent mid-test shutdowns.

• Data Storage & USB Export

  Stores up to 99 test results in internal memory for easy export and report generation via DataView software.

FAQ

Error Messages & Screen Symbols

Why does it say “Voltage Present”?:

The device is picking up stray voltage on whatever you’re testing. For safety, you need to clear that voltage completely before starting. If more than 20V hits the C1-C2 terminals, the front panel fuse will pop right away to protect the unit.

What does the “>” (Overrange) symbol mean?:

The resistance is just too high for the current setting you picked. Just turn the knob to a higher range.

Why is the lightning/wave symbol (Noisy Measurement) showing up?:

There’s too much background noise or interference in the area, so the reading might not hit that 0.25% accuracy guarantee.

Operation & How to Use

How does the 4-Wire Kelvin setup work?:

New users ask about this a lot. It uses 2 pairs of leads: source leads feed a steady current, and sense leads read the voltage. If you’re using Kelvin clips, make sure both sides of the jaw make solid contact, since each side has a different job.

What’s the Polarity (+/-) button for?:

It automatically flips the current direction and gives you the average. Super handy for canceling out background DC current or induction so your numbers stay accurate.

How do I turn on Auto Mode?:

Just hold down the MEM button for over 2 seconds. It’ll start testing the second the probes touch the target, and save the reading as soon as you pull them off.

Data & AEMC 6240 Software

How do I get the test data onto my PC?:

The AEMC 6240 has a built-in optical port. You’ll need the included DataView software to pull your saved readings (holds up to 99 tests) over the cable and make official reports.

Battery & Care

What kind of battery does it take and how do I care for it?:

It runs on a 6V NiMH rechargeable battery. People often run into issues where the unit won’t turn on after sitting in storage for a while. To keep the battery from dying completely, top it off every few months even when you’re not using it.

Technical Specifications

What’s in the Box

1. AEMC 6240 Micro-Ohmmeter Unit

2. Set of 10A Kelvin Clip Leads (10 ft)

3. Rechargeable NiMH Battery Pack & Power Cord

4. USB Cable & DataView Software

5. Soft Carrying Bag / Protective Case

6. User Manual

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