Teledyne offers relays that are normally closed of the S2840B SSR series. These devices are characterized by a normally closed contact when input is low or when the interfacing circuit is open. The container is "Hockey Puck" industrial standard.

This type of relays is characterized by a 280 VAC, 40 A with a 600 V over voltage tension; the control tension can vary between 5, 12 and 24 V with a dielectric power up to 4000 VAC.

The ceramic composition base and the use of Teledyne proprietary processes offer the device a high thermal impedance guaranteeing fast cooling even in extreme operating conditions.