Low resistance ohmmeters and winding resistance test sets, at first glance, might appear very similar. Both sets are used to measure very low resistances using an applied DC current , but that is where the similarity ends. Low resistance ohmmeters are well suited for a wide range of applications where measuring the integrity of a connection or bond is required. In these applications there is no storage of energy in the test specimen. When looking at the windings of a motor or transformer keep in mind that these windings are essentially large inductors. The higher the voltage and the larger the (MVA) capacity, the higher the induction and hence a potential hazard when applying DC test current. Standard low resistance ohmmeters simply do not provide the added safety features offered in a dedicated winding resistance test set such as the Raytech models WR50-12 and WR14 units.
Raytech WR50-12 Two Channel Winding Resistance Test Set is designed for a high degree of accuracy for the measurement of very low resistance of inductive loads.
The Raytech WR14 15 Amp Winding Resistance Meter is a battery or line-operated, field-portable instrument designed specifically to measure the dc resistance of all types of magnetic windings safely and accurately.