Watlow Series SD6L
The Watlow Series SD6L is a 1/16 DIN Limit controller. It is used as a redundant controller to prevent overheating due to failure of the temperature controller or controlling relay or actuator motor. These controllers feature dual display, a universal thermocouple input and mechanical relay output. On gas furnaces they are wired in series with gas and air pressure switches, and on electric ovens they are wired in series with the door limit switches to open a dedicated contactor.