Time-delayed safety relays

The emergency stop must be controlled and as rapid as practically possible. For heavy machinery, this often means that the machine needs to be braked to a stop before completely cutting off power. A time-delayed safety relay is used for this controlled stopping in stop category 1 applications. Typically, in frequency converter and servo motor applications, controlled stopping of the machine is desired. In this case, the relay’s immediate contacts issue a stop command, and the time-delayed contacts provide the final stop. Another application is keeping safety doors of dangerous machinery closed until the hazardous movement has fully stopped.