Current transformer to reduce the security factor - Database & Sql Blog Articles

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Inductance

To ensure that the current transformer maintains high accuracy under normal operating conditions and avoids excessive error during overcurrent situations to protect the measuring instruments, two common approaches are typically used.

First, when the number of ampere-turns in the transformer is low and high measurement accuracy is required, materials with high initial permeability and low saturation magnetic density—such as permalloy or ultrafine crystal alloys—are commonly used for the core. These materials help maintain precision even under varying load conditions.

Second, for transformers with a high number of turns, if the measuring winding cannot meet the instrument's safety factor requirements, an auxiliary transformer can be connected in parallel to the secondary circuit. This auxiliary transformer acts like a saturable reactor, offering high impedance at rated current but low resistance at higher currents. As a result, it limits the current flowing through the measuring device, protecting it from damage. However, when selecting this auxiliary transformer, it’s important to ensure proper matching so that the main transformer continues to operate accurately under normal conditions.

In practice, engineers must carefully evaluate both the performance characteristics of the transformer and the specific application requirements to choose the most suitable protection method. This ensures not only the reliability of the system but also the longevity of the measuring instruments involved.