Marsh Bellofram TBC On-Delay DIP Switch TDR time delay relay starts operating upon application of supply voltage to the input. The relay energizes once the delay period is completed. During or after the delay period, reset is achieved by removing the supply voltage. With the TBC Series, there is no false transfer upon removal of supply voltage until the delay period is completed. It provides a fast, precise and uninterrupted operation due to the quick recycle time.