Megger models also offer the highest resistance thresholds in their test circuits, meaning that contact resistance to the test probes does not pose a problem, even under the most hostile conditions. In areas where soil is unavailable, sufficient contact can be made by merely placing a coiled chain or contact mat on the surface. Auto-ranging digital displays complete the test in a matter of seconds, with accuracies available down to 0.001 Ohm.
The four terminal models allow the operator to measure soil resistivity in addition to making "fall of potential" ground electrode resistance measurements. The determination of soil resistivity is critical in the planning, design, and location of grounding systems.
Megger DET 5/4D and 5/4R Four Terminal Ground Resistance Tester
The DET 5/4R and DET 5/4D are fully automatic four-terminal instruments, designed for testing systems where the expected ground resistance is 10 ohms or less. They offer an expanded measurement range on both high and low ends and the accuracy required for resistivity calculations. The DET 5/4R and DET5/4D are simple to use (one button operation) and have auto-ranging and auto-error detection capabilities.
The instruments can be configured for either three- or four-terminal testing, at the operator's discretion. Installed grounds may be tested by either configuration: three-terminal for quick setup and ease of testing, four-terminal for enhanced precision by elimination of lead resistance.
The DET 5/4D and 5/4R are just part of our full line of ground resistance testers. For more information on the ground tester that fits your needs, contact AVO International.
AVO International, 4651 S. Westmoreland Rd., Dallas, TX 75237. Tel: 800-723-2861; Fax: 214-333-3533.