Thermostat User Manual

Opera

tion l

4-19

Operation

HTC DC Control Alarms

PASSIVE ALARMS

Passive alarms flash the alarm code and display process temperature until the

alarm condition goes away, or it becomes a shutdown alarm.

Code Description Alarm LED

P1 Process Temperature Deviation Blinking Red

SHUTDOWN ALARMS

Shutdown alarms flash the alarm code and display process temperature. The HTC

process air heater should stop when the process temperature is below 150°F

(65.6°C) but should still flash the alarm code until the Acknowledge Alarm button

is pressed. If the alarm condition is still active, the HTC cannot start, it will flash

the alarm code again. If the alarm condition is not active, the display should return

to the normal default screen display and the HTC is ready to run.

Alarms place the control in “standby” mode. After the alarm is corrected and

acknowledged, cycle the heater Standby/Enable switch to “Standby” then back to

“Enable” to restart the process control.

Code Description Alarm LED

A1 Process High Temperature Solid Red

A2 Process Temperature Loop Break Solid Red

A3 Process Heater Box High Temperature Solid Red

A10 RTD Integrity Solid Red

A39 EEProm Write Error-Internal Control Solid Red

Board Problem

A49 Process Protection High Alarm Solid Red

A50 Process Differential Alarm Solid Red