DLRO100 series of digital low resistance micro-ohmmeters

Overview

The DLRO100 series of digital low resistance micro-ohmmeters delivers a test current of 100 A DC and a max output current (DC) of 110 A, with a measuring range of 0.1 µΩ to 1.999 Ω and a resolution of 0.1 µΩ. The instrument provides a smooth DC output with ramp-up and ramp-down and negligible ripple to reduce unwanted tripping of parallel equipment during tests. Power options include battery and mains operation; units can be fitted with a user-replaceable, high-power rechargeable Li-ion battery of less than 100 Wh that provides up to 200 manual/automatic tests per charge and charges in 2.5 hours. The DLRO100 series is portable at 7.9 kg and features a large LCD display, high noise immunity circuitry for stable readings, and enclosures rated IP54 (lid open). Safety features include a CAT IV 600 V rating, DualGround™ support (with optional DC clamp), and LED indicators. Data storage and communication options include Bluetooth and USB, with internal memory and USB drive download available on some models; available lead lengths are 5, 10, or 15 metre CAT IV 600 V leads, and the unit accepts a terminal adapter for spade-type connectors and uses banana jacks for voltage sensing leads. Explicitly supported applications include checking the resistance of busbar and cable joints, measuring wire and cable resistance, and verifying lightning conductor bonding. The DLRO100 series is intended for testing switchgear and circuit breakers during manufacture and in the field, and for production testing of circuit breakers, high voltage switchgear, welded joints, and connections. Additional stated transport and aerospace applications include railway rolling stock ground connections and manufactured joints, railway lines and conductor rails for commissioning and maintenance, and aircraft frame bonds and static control. The series is designed around the 100 A test current to meet standard requirements for circuit breaker contact resistance testing (IEC requires 50 A or greater, IEEE requires 100 A or more) and supports DualGround™ techniques and a smooth DC output to minimise accidental relay tripping during such tests.