I read with great interest the subject matter on time delay relays (Chapter 5)--realizing that a relay is nothing more than a fancy switch. Each of the 4 types talked about in the lesson mentions characteristics of the relay when the coil is unpowered (de-energized). However, the relay I purchased a few years back from Diversified Electronics (TDE-24-AKA-010) requires a constant supply of voltage whether it is operational or not. It is my understanding that a "non-time delay" relay does not need this constant voltage. It only gets the necessary voltage when the relay is asked to make or break contacts. So, my question is "why is the constant voltage needed on my time-delay relay?" Obviously, this steady supply of voltage is not being supplied to the coil--or the device (alarm) I am controlling would always be sounding.