ABSTRACT
Maximum current protection relays are the basic components in a majority of types of
powerful electrical and electronic devices and also have use in power engineering.
Analysis of the trends in relay technology development shows that the major relay
developers do not share a solid and consistent direction for simple current relay de-
sign improvement. For instance, some experts reason that certain families of electric-
mechanical relays currently in mass production need to be replaced by static IC relays. At the same time, they claim that regular electric-mechanical relays (including
the simple maximum current relays) are most reliable and affordable for many electric
utility companies, and will, therefore, be used in the majority of control and protec-
tion systems. It is important to note that the modern electric-mechanical relay is a
high speed device, which is insensitive to pulse and high-frequency interference and
surge voltage. It exhibits a very robust behavior in overload modes and has a satisfac-
tory reset ratio. One has to agree, though, that electric-mechanical relays usually con-
sist of many high precision expensive components, the production of which becomes
inefficient for the relay manufacturer.
