Timing relay has device that delays the immediate activation or deactivation of the armature when power is applied to or removed from the relay (or both)
Older units used pneumatic/fluid cylinder or motor/gear arrangements.
New styles uses electronics,R/C network to generate delay.
Timing relay contacts are -
a)Specified by style of contact -Normally open -Or Normally closed
b)Specified by delay operation -timed closing -Timed opening
NOTC (Normally Open,Timed Close)
The direction of the contacts motion is identical to regular NO contact,but there is a delay in closing contact.
Contacts are open before coil is energized,timing occurs when coil is energized.
This type of contact is alternatively known as a normally-open,on-delay.
NOTO (Normally Open,Timed-Open)
This type of contact is normally open when the coil is de-energized and closed by the application of power to the relay coil.
The timing action occurs upon de-energization of coil rather than upon energization.
Alternatively known as a normally-open,off-delay
NCTO (Normally closed,Timed Open)
Contact is normally closed when the coil is de-energized.
Contact is opened after the coil has been continuously powered for the specified amount of time.
Alternatively known as a normally-closed,on-delay.
NCTC (Normally Closed,Timed-Closed)
Contact is normally closed before the coil is energized,and opened by the application of power to the relay coil.
The timing action occurs upon de-energization of the coil.
Alternatively known as a normally-closed,off-delay.