Alarm disabling unit for production equipment with long stop warning
I built this module for Sensonor ASA back in 2007, I have no idea if it is alive today.
The purpose of this module is to make it possible to the operator to reset the alarm on the production equipment, but still make sure that the alarm sounds at the next fault. Today there is no way to turn off the alarm until the situation is cleared, but with this module that is now possible. Earlier the operators would remove the relay for the alarm, this gave an unfortunate long stop time if the relay was not placed back and the equipment faulted silently.
The production equipment has two chambers with controlled temperature, when the equipment stops the temperature in the cold chamber becomes unstable. When the emergency shutdown is triggered, this is needed for accessing the guard doors, the LN2 (liquid nitrogen) supply is closed. Therefor one doesn't want the equipment stopped for too long.
When a alarm situation occurs the red LED flashes and the production alarm sounds, by pressing "reset alarm" the voltage to the sound alarm is cut. The red LED lights continuously when the alarm is reset. When the alarm situation is no more the red LED turns off and the voltage to the sound alarm is restored. When a new fault occurs the procedure is repeated.
Warning long stop
If an alarm situation persists more then 30 or 60 minutes (jumper setting) the module will sound the alarm again. That means if the previous alarm was reset the voltage to the sound alarm will now be restored, blue LED starts flashing. This alarm is reset the same way, by pressing "reset alarm" the voltage to the sound alarm relay is once more cut. The blue LED will now be on continuously. The purpose of this alarm is to make the operators aware that they should consider defrosting the cold chamber is the equipment is left in standby much longer.
- PD.0 Reset button
- PD.1 Stack lights signal
- PD.2 Jumper for setting long stop timer
- PB.0 Red LED
- PB.1 Blue LED
- PB.2 Stack lights relay N.O
- PB.3 Power LED
|3||Stack lights in + (to optoisolator)||Green|
|4||Stack lights in - (to optoisolator)||Blue|
|5||Stack lights relay +||Yellow|
|6||Stack lights relay - N.O||White|
- GND to internal reset button (Without resistor)
- Signal from internal reset button (With resistor)
- GND to stack lights relay (D-sub 6)
- Signal from stack lights
- Red : + (D-sub 3)
- Blue : - (D-sub 4)
- 24V supply voltage
- Red : + (D-sub 1)
- Blue : - (D-sub 2)
- 24V to stack lights relay (D-sub 5)
- Jumper for setting long stop timer
- With jumper : 30 min
- Without jumper : 60 min