Thermon TraceNet TCM 18 - Manual (Page 74)

Self-regulating or power limiting heater
may be operating at cooler than design
pipe temperatures due to processing con-
ditions and thus heaters may be drawing
higher current values. Increase high current alarm set point (if
approved by project engineer).
Self-regulating or power limiting heater
may be operating in its cold start regime. When reading current on one of these
type heaters, it is necessary to read the
current at steady state. One may have
to wait as long as 5 minutes for heater
steady state values. After five minutes the
current value will continue to drop as the
pipe or equipment begins to warm.
Heater circuit may be longer than antici-
pated in the design stage. Verify installed length (if possible) and if
different review design. If length is differ-
ent but performance-wise the “as built” de-
sign is acceptable, initiate “as built” draw-
ing change and change controller high
current setting.
Wrong heater wattage or heater resis-
tance may be installed. Check heater set tags or markings on
heater cable against installation drawings.
As an additional check, disconnect heater
from power and measure DC resistance.
Heat tracing may be powered on wrong
voltage. Recheck heater supply voltage.
Current sensing circuitry may have en-
countered a problem. Use a different current clamp type meter
which is known to be accurate and do
a comparative reading. Investigate cur-
rent measurement circuitry further. Note
that one should only read heater currents
when the heater is 100% on.
PN 50316_0514 70