One way to detect problems on welded joints and relay contacts is by using a digital low resistance ohm meter. It detects internal problems of joints or contacts by measuring its resistance. A small increase in its baseline resistance means that there is a change in composition of the material. Rust, dirt, pollutants or thinning of metal contacts are the common causes of resistance change.
The Megger 247001 DLRO is a popular tester widely used by electricians because of its features. This tester has an output current of up to 10 amperes with a resistance range of 0-60 ohms. This Megger DLRO is portable and manufactured to withstand harsh conditions, suitable for field applications. You can use this tester in various applications like transformers, motor windings, generators, bus bars, welded joints, rails, pipe bonds, metal alloys and graphite electrodes. It has a reverse current mode to offset the thermocouple junction on dissimilar metals. Readings can be viewed on its large LED display and has a built-in automatic zero circuit to minimize errors in test results.