Summary Of Alarms - Selectable Alarms; Alarm Relays; Power Lamp; Burner Bypass Switch - Novatech 1635 User Manual

14. 'DAC Cal Fail'
The digital to analog and voltage isolator circuit has been found to fall well outside the normal calibration
specifications. Default calibration constants have been used to keep the output channels working if at all possible. This
check is only performed when the 'AUTO CAL' button is pressed.
15. 'Gas Cal Err'
Probe does not correctly calibrate to calibration check gas1.
16. 'Burner bypass'
The safety interlock relay has been bypassed by turning on the 'BURNER BYPASS' switch on the PSU / terminal
printed circuit board. Refer to Section 2.20.
17. 'Watchdog Timer'
Microprocessor error. This alarm will not appear on the display. The common alarm relay will be forced open circuit.
If the watchdog timer senses a malfunction in the microprocessor, it will attempt to reset the analyser every 2 seconds.
After two resets the alarm relay contacts will go open circuit.

3.3.2 SUMMARY OF ALARMS - SELECTABLE ALARMS

There are three user configurable alarm relays. Any or all of the following functions can be selected for each relay.
18. 'Probe Temperature'
The probe temperature is under 650°C. The oxygen reading is therefore invalid. If the probe heater has been on for
more than 20 minutes and the temperature is less than 650°C a 'heater fail' alarm will occur.
Note: The 'Probe Temp' relay function is used with unheated probes to indicate oxygen reading is invalid (the probe is
below 650°C), in case the process temperature falls below this level. For heated probes this relay will be energised
while the probe is heating up from ambient.
19. 'Cal in Progress'
A calibration check is occurring, either manual (in RUN mode) or automatic.
20. Alarm Horn
This is not an alarm condition. If one of the three user configurable alarm relays have 'Alarm Horn' enabled, the relay
will have closed contacts only when there is an unaccepted alarm on the analyser. Press the alarm button twice to
accept any new alarm to cancel the horn relay.

3.3.3 ALARM RELAYS

The alarm relays are fail safe. That is, the contacts will be closed during normal operation, and will be open circuit if
there is an alarm or if the power is removed from the analyser.
3.4

POWER LAMP

Illuminates when power is connected to the analyser. If the lamp is flashing, the watchdog timer is attempting to reset
the microprocessor. Replace the 1630-1 microprocessor PCB.
3.5

BURNER BYPASS SWITCH

This switch is mounted on the terminal PCB near the POWER switch.
There are two ways of enabling the heaters and alarms for the probes and sensors: -
Use the safety interlock on terminals 18 & 19 (BURNER ON switch), or turn the BURNER BYPASS switch to the ON
position.
While the BURNER BYPASS switch is on there will be an alarm, "Burner Bypass".
If it is not needed to have the analyser interlocked with the combustion appliance terminals 18 & 19 can be bridged
together.
August 2009
1635 Water Vapour Analyser 29