Thermon TraceNet TCM 18 - Manual (Page 21)

After this start-up message, the TCM18 will immediately proceed to operation in its
SCAN MODE.
The TCM18 will operate in a heat tracing circuit SCAN MODE during normal oper-
ation. That is, the LCD display will automatically scroll through each enabled heat
tracing circuit number, indicating the actual measured temperature and the control
set point for maintain temperature on the first two display screen lines. The third dis-
play screen line will indicate the heater status (ON % or OFF) and the heat tracing
circuit heater current value. The fourth display screen line will indicate any alarm(s)
present on the circuit displayed. Where multiple alarm events occur on a circuit, the
TCM18 will display only one alarm message at a time until all have been cleared. A
typical SCAN MODE screen when the heat tracing circuit is operating normally is as
shown below in Figure 9:
CKT 7 TEMP= 61 ◦ C
MAINTAIN TEMP= 60 ◦ C
HEATER ON 80% 12.0A
Figure 9: Typical TCM18 information when in SCAN MODE
Note that the fourth message line on the display screen will be empty as long as
there are no alarm or trip conditions present on a given circuit. During SCAN MODE,
the TCM18 will sequence through all enabled heat tracing circuits beginning with the
first circuit and then loop back to the first circuit after displaying the last circuit and
repeat the scanning process. A summary of all possible alarm messages follows.
Message Explanation
RTD FAULT
ALARM The RTD reading is out of the range when the resis-
tance value exceeds 313.7 Ohms or is less than 48.46
Ohms. In this case, either the RTD has not been con-
nected or has opened or shorted in service.
17 PN 50316_0514