Perma Pure GASS-2040 - Manual (Page 15)

15 GASS-2040 User Manual | Original Instructions
4.3 Systems Operation Monitoring
The PLC monitors the system parameters for proper operation and can alert personnel of
potential problems via an indicator light, or signal an external control system via digital outputs.
a. Alarm Output Operation – The system has three digital alarm outputs that can be used to signal
an external control system that a problem has been detected. Refer to the I/O Wiring section
for connection details on page 11. The definition of an active alarm is that the related output
will be OFF. During normal operation, (i.e. no active alarms), all alarm outputs will be ON. In the
event of a power failure to the system, all alarms will be in the active or OFF state.
- Low Dryer Purge Air Flow alarm - This alarm is initiated when the airflow that is used to
purge the dryer is too low. The airflow is sensed by a differential pressure switch located in
the lower enclosure and connected to the dryer purge gas inlet and outlet. At any time while
the dryer purge air is too low, this alarm will be active.
- Low Temperature alarm – This alarm is initiated when any of the system temperatures
fall below the respective setpoint by 5
O C as sensed by the thermocouples. At
any time the system temperatures is too low, this alarm will be active.
- General alarm – This is an alarm that is initiated by either of the two alarms above. At any
time while the system power is on and either of the two alarms above is active, this alarm will
also be active.
b. System Status Indicator Operation – The system power pushbutton/light serves as a basic
system status indicator and is located at the lower left hand side of the control panel. Based on
the status of the alarm outputs and whether the system has reached operating temperature or
not, the indicator light will either remain lit or flash at one of two different rates. There are
three modes of operation:
- Start-up/Heat-up mode – In this mode the indicator lamp will flash slowly at
approximately 1Hz. The system will stay in this mode until all of the system
temperatures achieve their respective setpoints.
- Normal Operation mode – In this mode the indicator lamp will remain lit and will not flash.
- Alarm mode – In this mode the indicator lamp will flash quickly at approximately 4Hz.
Two different system conditions can initiate this mode:
1. The system detects a low purge flow condition at any time. For example, power
to dryer heaters is interrupted to prevent damage due to overheating.
2. The system temperatures have all reached their respective setpoints (Normal
Operation mode attained) and one or more of the temperatures then falls below
the setpoint by more than 5
O C.
Note:
The actual Low Temperature alarm output is not affected by the system status mode and will
be active during any low temperature condition including Start-up/Heat-up.