AMPERIS PDRM-1A Digital Micro-Ohmmeter

Readings from 1 µΩ to 200 Ω with category-leading accuracy

PDRM-1A

Ohmmeters

PDRM-1A

1 A digital micro-ohmmeter

Measuring very low resistances by the four-point Kelvin method, in the field and in the laboratory.

Fully automatic micro-ohmmeter

The PDRM-1A is a fully automatic digital micro-ohmmeter: it selects its own range and injects up to 1 A DC to read resistances from 1 µΩ to 200 Ω, with an accuracy of 0.1% of reading ± 2 counts and a resolution of 1 µΩ over 4¾ digits. The rugged, sealed and light unit — 0.86 kg — suits both site work and bench testing.

Four points, zero contact uncertainty

Two conductors inject the current at the ends of the joint while another two read the voltage drop directly across the section under test, so the resistance of the contacts stays out of the measurement. The microprocessor cancels offset and parasitic voltages, and the heavily filtered inputs keep the reading stable even in the presence of strong magnetic fields.

Main features

• Three test currents — 1 A, 100 mA and 5 mA — automatically adjusted.
• Standard and differential operating modes, comparing against a stored reference.

• 128 × 64 pixel LCD display with two-level backlight.
• Low current injection for applications with small measuring contacts.
• Six rechargeable NiMH AA batteries: over 4000 measurements at 1 A.
• Automatic shutdown after 2 minutes; the backlight switches off after 30 seconds.

Applications and accessories

Applications

• Checking earth connections and power busbars with the relative measurement mode.
• Verification of welded joints made with high current and of mechanical connections.
• Testing circuit-breaker contacts and power fuses.
• Quality control of castings and electrodes.
• Non-destructive verification of exothermic welds in substations.

Example: inspecting earthing grids

The earth connections used for de-energised work are the main safety guarantee for field crews. With the relative mode, the PDRM-1A stores the reading from a reference connection and compares every new measurement with it, showing the deviation — a fast way to decide whether each point of the grid is acceptable.

Accessories

• Dual hand probes with replaceable spring-loaded tips (122 cm; heavy-duty version up to 3 m).

• 35 mm booster-type and 19 mm dolphin-type Kelvin clamps.
• Dedicated probe for exothermic welds; cable-elbow accessory.
• 9.5 µΩ reference resistance to validate the unit before work.
• Nylon pouch, 46 × 35 × 18 cm rigid case and custom-length cables.

PDRM-1A — TECHNICAL SPECIFICATIONS