Blog

To understand excitation current testing, it helps to start with magnetism. Every magnet has a magnetic field made up of lines of force. These magnetic lines leave the north pole and enter the south pole. The total number of magnetic field lines is called magnetic flux.

When a power or distribution transformer is disconnected from the power system, the transformer core may not return to a completely unmagnetized state. Some magnetic flux can remain in the core. This is called remnant magnetism or residual magnetism.

What does the future hold for our industry — especially when it comes to those all-important standards that ensure reliability, protect property, and help us to avoid injury or death? As we revise and update codes and standards from NETA, NFPA, IEEE, ASTM, NEMA, CSA, and OSHA, I think we should all read this very carefully, especially the summary.

Critical to Electrical Reliability and Safety for Industrial and Commercial Power Systems It happens in a fraction of a second – and what happens after that can mean the difference between the inconvenience of a power outage to a large-scale electrical failure and/or fire. Therefore, the assurance that your electrical power system does what it is intended to do is paramount.

Introduction: What Happened? At 5:45 a.m. on a particularly cold winter day, an industrial manufacturing plant experienced a significant electrical fault event on a 15 kV substation that feeds power to approximately 30% of the manufacturing operations. The main circuit breaker in one of the plant’s three medium-voltage substations experienced a fault, an arc flash event, and a subsequent trip of the entire lineup, apparently due to a rodent that caused a phase-to-phase fault in the 15 kV potential transformer (PT) compartment. The fault traveled into the medium-voltage bus assembly in the metal-clad switchgear lineup, ultimately causing the main breaker to trip and de-energizing a large portion of the facility.