Electrical test equipment is frequently used to measure resistance offered by a device to check whether the value falls within the acceptable range or not. Protective devices are some of the electrical components that frequently require resistance testing.
Since these electrical components are exposed to corrosion, vibration, and thermal and electrical stress, they have high chances of developing faults. In the ideal case, the resistance offered by contact points should be of the order of micro ohms. The low resistance value favors maximum power transfer. However, the environmental and operating stress can degrade the contacts below permissible levels and resistance values may increase.
Megger digital low resistance ohmmeter, a preferred choice among most customers, is used to measure very low levels of resistance by using Double Kelvin Bridge input to have minimal effect on the resistance reading. It functions by applying current across the device to be tested and measuring the voltage drop across it. The DLRO’s microprocessor takes the reading of the drop in voltage and calculates resistance. A good quality contact point would have a smaller voltage drop across it, and thus lower values of resistance. DLRO test permits the user to check whether the contact points are good enough to be kept in operation or not.