Control relays normally have normally open and normally closed contacts on multiple poles. A pole of a relay is one switch element including a common, normally open and normally closed contact.
A contactor (or Motor starter) normally has 3 normally open contacts for switching 3 phase power. Some have auxiliary contacts for external logic. You can see examples elsewhere in the knowledge tree. Search for "contactor" to see most varieties we use at Milnor.
Like most relays, a control relay has a electromagnetic coil that pulls in the switching element that carries the switch elements.
See the image below showing the contact example on one pole.
Notice that in the unpowered state the Common and Normally Closed contacts are made.
When powered, the Common and Normally Open contacts will be made.
Milnor uses both 3 pole and 4 pole control relays. The numbering on the poles is always similar and DOES NOT follow the markings on a 14 pin relay base.
