Sensor #2; Measuring Temperature And Setpoint; Operation - EngA C-TRAC3 Installation, Operation And Maintenance Manual

A
to satisfy the SPC in its present mode and the discharge temperature slips outside of the discharge
temperature dead band then it will begin timing for a mode change. Once the timing is completed, it can
change modes. If the timer is active and the discharge temperature slides back into the dead band, the
mode change timer is reset. If the current operating mode becomes disabled the C-TRAC3 will immediately
move into the next mode. A preprogrammed option can disable the unit operation if no modes are
available. The table below indicates which 24Vac input terminal can enable or disable its corresponding
mode.
Mode Terminal
Heat
Economizer
Cool
The C-TRAC3 will not always be able to exactly maintain the SPC. Enabling a cooling compressor, for
example, may cause the discharge temperature to fall below the SPC. When the compressor is disabled
the temperature may rise above the setpoint. On average, however, the discharge temperature will
closely match the SPC.
The C-TRAC3 controls to a +/-2°F dead band of the SPC when in heating and economizer mode. The
cooling dead band is based on the dry bulb temperature drop of each stage of mechanical cooling.

SENSOR #2

The C-TRAC3 is has the option of using, and controlling to, two sensors. Some equipment may incorporate
2 discharge air sensors for improved temperature control. Multi-zone equipment use sensor #1 for the
hot deck, and sensor #2 for the cold deck. Dehumidification equipment use sensor #1 for the reheat
(leaving) section, and sensor #2 for the pre-cool section.

MEASURING TEMPERATURE AND SETPOINT

The calculated setpoint (SPC) and the actual temperature can be monitored using a DC voltmeter and the
temperature test points and a DIP switch block mounted on the face of the C-TRAC3 (located near the
RS232 serial connection). Note that the calculated setpoint includes any resets to the setpoint. Refer to
Table 4 on page 14.

OPERATION

As the C-TRAC3 is configurable and will vary in its operation unit to unit, it is imperative that the unit
function, terminal designation sheet and wiring diagram be reviewed to understand how the control is
operating for each particular application.
CAUTION:
All of the remote wiring must be complete and functional before attempting to start
the unit.
HS Heating is allowed with 24Vac at the terminal.
E Economizer is disabled to minimum with 24Vac.
A Cooling is allowed with 24Vac at the terminal.
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Table 1
Operation
C-TRAC3
Jan 13 R5