Wiring Diagram symbols

Could you clarify the meaning of the symbols depicted in the attached file: one comprising two parallel lines intersected by a diagonal stroke, and the other comprising two parallel lines without the stroke? 

  
     
 

Those are internal relays.

Two lines, normally open.

Two line with diagonal, normally closed.

Abbreviations such as GCR, Generator Control Relay.

UV, Under Voltage.

OV, Over Voltage.

These are depictions to simplify the circuit. There doesn't have to be a physical relay. It could be an actual transistor that's doing the job. They could be logic circuits also.