Types:
Electro-mechanical:-An electrical signal applied to a coil causing a
mechanism to activate thereby changing a set of mechanical contacts.
SSR:- Solid state comes from the electronic industry, implying no
moving parts- Uses electronic switching devices like transistors,
SCR/ thyristors,
triacs etc.
*There are proportional control devices that looks just like SSRs but
in effect they are controllers of which the output is
a function of a linear input control signal.
One cannot always tell the physical difference between a
electromechanical relay and a SSR
since some relays could be sealed and externally look alike.
