Determining the electromagnetic characteristics of a slow release actuator

This paper presents a new method to determine the electromagnetic characteristics of slow release B1 relay, which is used in US railways. This relay operates few seconds after it is energized or de-energized. The slow operation of this relay is accomplished by short circuits loops around the magnetic core of the relay. The operation of the B1 relay is highly affected by electromagnetic characteristics of the relay, therefore, this research aimed to obtain the B-H or equivalently λ-I curve of the relay core. Since the relay has short circuit loop around its core, it is not possible to obtain its λ-I curve by conventional methods. Thus, different methods have been proposed, and finally the most efficient one is chosen and explained further in this paper.