A contact resistance test (also known as a ductor test) measures the resistance of electrical connections such as joints, terminations and connectors. These can be connections between any two conductors, for instance busbar sections or cable connections. The test measures the resistance at the micro- or milli-ohm level and is used primarily to verify that electrical connections are made properly, and can detect the following problems:
Circuit breakers are used everywhere – in our homes, offices, and electric facilities. The degradation of the electrical insulation that is an integral component of these protective devices, can be influenced from both environmental and operational stresses. Additionally, oxidation and ware of circuit breaker contacts can lead to relatively high resistance connections and overheating of the circuit breaker. In the worst case, contacts can become welded together, thereby defeating the protective intent of the circuit breaker. This is why it is important to utilize the proper electrical test equipment when testing, to ensure that the circuit breaker is properly fulfilling its intended purpose.
Ohmmeters are an electronic device that measure electrical resistance, and come with different levels of sensitivity. Some are designed to measure low-resistance materials, while others measure higher resistance. The higher resistance the material has, the less current will pass through it.
An ohmmeter is typically not used to measure resistance across an entire circuit, but rather through various parts of the circuit, although it can be used to test that a circuit is not broken.
With results within 0.05%, the AEMC 6250 10A Micro-Ohmmeter utilizing a four-lead Kelvin method, and features a four-input, manual-ranging meter with seven test current/resistance ranges for precise, low-resistance measurements from 0.1 microohm (μΩ) to 2,500 ohms (Ω) of inductive samples such as:
With the AEMC 6250 10A Micro-Ohmmeter resistance measurements are automatically calculated and displayed, taking into account the measurement value, ambient temperature, reference temperature and metal temperature coefficient. Sample temperature can be manually entered by the operator or directly measured by theAEMC 6250 10A Micro-Ohmmeterwith an external RTD temperature probe.
TheAEMC 6250 Micro-Ohmmeteris uniquely designed to conduct tests on both resistive and inductive material, with operator selection directly from the front panel. Three test modes are available: resistive (instantaneous test), inductive (continuous test), and auto (repetitive test). Up to 1500 measurements can be stored and printed directly to a printer or from a PC.