No Current Imbalance Doesn’t Mean No Problem

Just because the three phase current data being returned by the installed relay is balanced, doesn’t clear the power circuit of possible anomalies. Remember from previous tips that the opposition to AC current is influenced by impedance, which is the combination of reactance and resistance. Not just resistance. A high resistance connection may be a small part of the overall impedance, but can still create a significant amount of localized heating. This localized heating can lead to big problems if not corrected. Waiting until the problem is severe enough that the resistance element dominates the total impedance and changes the AC current may be too late and risk a single-phase fault. Using the MCE® technology for precision resistance measurements will give an early indication of power circuit anomalies so they can be repaired before causing a high current imbalance.

Check out this case study comparing current and resistance imbalance.