TRACE
MATE-277V
Chapter 3 APPLICATIONS
3.1
Mechanical Thermostat Replacement
Mount the control unit near the pipe being traced in a
location with easy access. Replace the thermostat capil-
lary tube with an RTD mounted on the pipe and connect
the existing heater and power wires to the TraceMate-
277V as shown in Figure 3.1. A green alarm status light,
visible to maintenance personnel, is connected to the
TraceMate-277V LED alarm output and should always
be on. If the light goes off, the following may have
occurred: (1) bulb burnt out (fail-safe indication); (2) no
control power available; (3) system fault. Examine the
LEDs inside the TraceMate-277V to determine the cause
of the alarm.
Advantage of this scheme over mechanical thermostats
is: easy setpoint adjustment and early warning of system
faults with TraceCheck system exercising every 24 hours
and rapid fault diagnosis in the event of a problem.
Alarm Annunciator
If an alarm annunciator or programmable controller is
available, terminal 10, 11 & 12 can be used as a low cost
digital interface. These terminals are form c dry con-
tacts. A separate voltage source must be connected across
these terminals as shown in Figure 3.2 for the annuncia-
tor to sense the alarm logic.
Switching Requirements
Two different TraceMate-277V models are available to
accommodate different power configuration of electric
heat trace. The single pole switching model is used for
phase to neutral power feed. The dual pole switching
model is used for phase to phase power feed. Two SCRs
are used in this model to ensure both lines are switched
off. Not only is this an electrical code requirement, but to
ensure both connections to the heater are not hot when the
controller is not calling for heat. This is especially
important for the ground fault function to operate
properly since switching only one line there is a 50%
chance that the heater output is properly tripped.
Figure 3.1 Thermostat Replacement
Figure 3.2 Alarm Annunciator
