12LS Controller Installation and Operation Manual, Rev 3 ... - Watlow

3.4.1 PID CONTROL AND ALARM OUTPUTS CONNECTIONSTypical digital control outputs utilize external optically- isolated solid-state relays. These relays use a 3 to 32vdc inputfor control and can be sized to switch up to 100 amps at 480vac. For larger currents these relays can be used to drivecontactors.|-----------------------------------------------------|¦ NOTE: Control outputs are SINK OUTPUTS. They will be¦¦low when the output is ON. They should be connected ¦¦to the minus (-) side of SSRs. ¦|-----------------------------------------------------|Example of Heat/Cool And Alarm Outputs Connections:SSR 1 SSR 2 SSR 3|------| |------| |------|RTB TERMINALS PIN ¦ - + ¦ ¦ - + ¦ ¦ - + ¦|------| |------| |------|PID HEAT 1 9 ||-------| ¦ ¦ ¦ ¦ ¦¦ ¦ ¦ ¦ ¦PID COOL 1 33 ||----------¦---------| ¦ ¦ ¦¦ ¦ ¦ ¦+5VDC 1 ||----------|------------|---------¦--|¦DIG OUTPUT 1 28 ||---------------------------------|3.4.2 PID OUTPUT LIMITINGThe output from each loop's dual heat/cool output may be limited to a value less than 100%. This level may not beexceeded by the PID control action. This limit on the control output may be limited by a period of time and thanreturned to full 100% output or it may be a continuous limit until changed by the programming keys.The limit time delay is restarted whenever:a) A new time period is entered.b) A loop is switched from MANUAL to AUTO mode.c) The controller is restarted(powered up).The time period is adjustable from 1 to 999 seconds for a maximum period of time of over 16 minutes. A time of 0seconds will be displayed as C, the same as for Continuous.The Output Limiting is disabled by setting the value to 100%. The control mode of ON/OFF has no output limitingavailable.The output limiting may be used for "Soft Start" type of requirements of different processes. May also be used torestrict the energy into a process, thus tailoring the controller output to the process requirements.3-15