EngA C-TRAC2

A C-TRAC2.1 MANUAL
IOM-12 Page 8 March 1999 R1
The economizer is to be configured to one of the following operation modes:
1. Dampers go to minimum fresh air position whenever the first compressor starts. (Dipswitch 6 OFF and
dipswitch 7 ON.) 1 and 2 (dip switches 6 and 7 are both ON).
2. Dampers go to minimum fresh air position whenever the outside enthalpy or the outside temperature is high.
(Dipswitch 6 is ON and dipswitch 7 is OFF with a 24-volt ac input to terminal E).
NOTE: The power applied to terminal E must be from the same source as the power supply to the
C-TRAC2.1 terminal H.
3. A combination of 1 and 2 (dip switches 6 and 7 are both ON).
4. Constant compressor load (dip switches 6 and 7 are both OFF). In this mode of operation the C-TRAC2.1 will try
to operate with maximum outside air. If the cooling demand drops off, instead of shutting off a compressor, it
will first throttle back the inlet air damper. If there is still not enough load in the return air the compressor will
be cycled off. This will maintain a more constant compressor load and keep the discharge temperature
satisfied while minimizing compressor cycles. Operation in this mode will require an external economizer
ambient lockout and separate minimum position pot. For the 0 – 10 VDC 2 wire damper motor signal a 10K
OHM pot is used externally or the SGA24 remote minimum pot can be used externally. When a 10K OHM
pot is used ensure that the diodes are placed in proper ‘bias’. (See drawing for various options). For the 3 wire
Honeywell damper motors wired to RBW a minimum position pot such as Q209 or S9638 is used.
Cooling
Compressor Ambient Lockout
The mechanical cooling cannot operate unless the outside ambient is above a pre-selected limit. The ambient
control is a separate control that is wired to the C-TRAC2.1 terminal A. When the outside temperature is above
the set-point of the ambient control then a 24 VAC signal is applied to terminal A. The C-TRAC2.1 is able to cycle
on the cooling stages.
NOTE: Use the same 24 V power on terminal A as is being used to power the C-
TRAC2.1 terminal H.
The discharge air set point is the same for both the economizer and the mechanical cooling.
Cooling Delays
The C-TRAC2.1 contains time delays for minimum run, minimum off, and inter-stage timing. These delays are all
a non-adjustable 4 minutes. For service purposes turning on dip switch 8 can shorten the above delays.
NOTE: This switch must be left in the off position during normal operation. If it is left ‘on’ it
may result in compressor failure or lack of control stability.
In addition to the above delays there may also be a cooling integral demand delay. This delay is calculated by the
C-TRAC2.1 based on time and demand. This delay is non-removable and ranges in time from 1 to 8 minutes.
If the compressor ambient control is switched while compressors operating, the C-TRAC 2.1 will switch to heating
mode as it thinks that the ambient was too cold for compressors to run!
To Simulate a Call for Full Cooling
To simulate a call for full cooling open circuit the discharge air sensor by removing the wires from either “Q” or
“M”.
XII. BURNER OPERATION
Burner operation is supervised by controls outside the C-TRAC2.1. In many applications the C-TRAC2.1 will
supply a modulating 0-10 VDC signal to control the burner control module (i.e. DJM, G-TRAC, etc.) which in
turn modulates the burner.