Relay Specifications- Operate Time

What is the Operate Time of a Relay?

The Operate Time of a relay is the transition time from the moment when voltage is applied to the relay coil to the moment the normally open switch contact(s) close.

The Operate Time for relays usually are in the milliseconds range; for example, a Panasonic JJM Series automotive relay has an operate time of 10ms, when the nominal voltage is supplied directly to relay coils, without any external components such as resistors.

The Operate Time of a relay includes the time for the coil to build up the magnetic field (magnetic attraction is necessary to attract and close the contact), the transfer time of the moveable contact (from its open to its close position), and the bounce time after the closing of the switch (relays can bounce up and down a number of times before finally settling permanently in its close position).

References
http://relays.te.com/kilovac/appnotes/operatetime.asp