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Several people have been looking for wiring diagrams to include a timer in their oven controls. There are different ways of incorporating a timer into the wiring, but here is a fairly simple way using a Sestos B2E digital timer. I chose this timer as I had one available for testing. Other timers may or may not work as described here. A wiring example showing before and after for an SSR set-up is included.
Wiring:
The method I’ve chosen adds the timer between the pid and the relay(ssr or contactor). If you already have an on/off switch between the pid and relay to allow changes to the pid’s parameters with the elements disabled it stays as is, if not a simple on/off spst switch needs to be added. If you are using an AC input contactor make sure the switch selected is rated for AC voltage.
I suggest you wire the timers input voltage terminals 9 & 10 into the pid's input voltage terminals so they power on together. They can both be protected by a small 1 amp fuse if desired. The Output1 wire from your pid that goes through the switch to the relay, as discussed above, now needs to go to the B2E's terminal #7, and a new wire goes from the B2E terminal #6 to the relay’s terminal that you just disconnect the wire from.
The B2E has a reset button on the front panel, but we also need to add a pause switch for the timer. This is required to restart the whole process as described at the end of this description. To wire a pause switch for the timer you need to add an on/off spst switch to your control box and connect wires from the B2E's terminals #2 & #5 to the switch.
Once you are able to power the B2E timer on perform the following parameter changes:
Press the mode key for 3 seconds.
Change "Unit" to "sec"
Change "node/Mode" to either up or countdown, your choice
Change"node/time" to “one shot” dashes will appear "------"
Change "In" to PnP
Change "Lock" to off
With this setup, when the relay switch is enabled between the pid and the timer the elements will heat and you can begin to monitor PMT. Once PMT is reached, hit reset on the timer which will initiate the countdown/countup. At expiration of the timer, the B2E's contacts 6 & 7 will open and disable the relays input power and therefore the elements.
To start another cycle or turn off the optional alarm, turn the pause switch on, then push the B2E's reset button. This will energize the elements and the pid will manage to the set point. If you are just resetting the alarm and not ready for another oven cycle turn the element switch off. If you are ready for another cycle leave or turn the element switch on, monitor PMT and when achieved turn the pause switch to off to start the timed event.
Optional Alarm:
A timer expiration alarm can easily be added to this set-up. If using ssr's you will need a buzzer or alarm rated 12VDC. For contactors a 120VAC alarm is required. To disable the alarm once it sounds at the end of the timed cure cycle follow the procedure described above to start another cycle.
There are certainly other methods of incorporating a timer, but this method allows you to run the oven to achieve PMT, start the timer and at timer expiration, disable the elements and turn on an alarm.
Sestos B2E timer.pdf
Wiring:
The method I’ve chosen adds the timer between the pid and the relay(ssr or contactor). If you already have an on/off switch between the pid and relay to allow changes to the pid’s parameters with the elements disabled it stays as is, if not a simple on/off spst switch needs to be added. If you are using an AC input contactor make sure the switch selected is rated for AC voltage.
I suggest you wire the timers input voltage terminals 9 & 10 into the pid's input voltage terminals so they power on together. They can both be protected by a small 1 amp fuse if desired. The Output1 wire from your pid that goes through the switch to the relay, as discussed above, now needs to go to the B2E's terminal #7, and a new wire goes from the B2E terminal #6 to the relay’s terminal that you just disconnect the wire from.
The B2E has a reset button on the front panel, but we also need to add a pause switch for the timer. This is required to restart the whole process as described at the end of this description. To wire a pause switch for the timer you need to add an on/off spst switch to your control box and connect wires from the B2E's terminals #2 & #5 to the switch.
Once you are able to power the B2E timer on perform the following parameter changes:
Press the mode key for 3 seconds.
Change "Unit" to "sec"
Change "node/Mode" to either up or countdown, your choice
Change"node/time" to “one shot” dashes will appear "------"
Change "In" to PnP
Change "Lock" to off
With this setup, when the relay switch is enabled between the pid and the timer the elements will heat and you can begin to monitor PMT. Once PMT is reached, hit reset on the timer which will initiate the countdown/countup. At expiration of the timer, the B2E's contacts 6 & 7 will open and disable the relays input power and therefore the elements.
To start another cycle or turn off the optional alarm, turn the pause switch on, then push the B2E's reset button. This will energize the elements and the pid will manage to the set point. If you are just resetting the alarm and not ready for another oven cycle turn the element switch off. If you are ready for another cycle leave or turn the element switch on, monitor PMT and when achieved turn the pause switch to off to start the timed event.
Optional Alarm:
A timer expiration alarm can easily be added to this set-up. If using ssr's you will need a buzzer or alarm rated 12VDC. For contactors a 120VAC alarm is required. To disable the alarm once it sounds at the end of the timed cure cycle follow the procedure described above to start another cycle.
There are certainly other methods of incorporating a timer, but this method allows you to run the oven to achieve PMT, start the timer and at timer expiration, disable the elements and turn on an alarm.
Sestos B2E timer.pdf