Wiring; Heat Output; System Timings; Dip Switches And Pots - EngA C-TRAC2 Installation, Operation And Maintenance Manual

A

IV. WIRING

Power supply = 24 VAC @ 0.9 amps.
The C-TRAC2.1 terminals "H and N" require a separate 24 VAC, 20 VA class 2 isolation transformer
supplying power to only "H and N". Often this is best to not have a grounded neutral as side stray voltages
can interfere with C-TRAC operation and create strange operating situations.
Terminal "N" should be wired to the neutral which is common to the same power source supplying power to
terminals ("E, A, K"). All remote wiring less than 50 feet long should be installed in clean electrical
environments and attached to terminals "Q, U, X, Y, V, Z" . Wire should be a minimum of 22 ga twisted pair
wire. (Shielded wire is best.) For longer runs and electrically noisy installations, the use of a minimum 20 gauge-
shielded wire is recommended. (Shield should be grounded at unit end only, other end taped.)
:
NOTE
If there is to be an interruption of only the C-TRAC2.1 power such as by a time
clock shutdown at night, there cannot be any other load connected to the C-TRAC
terminals H, A, E, or K. If this wiring is not correct there may be about 18 volts on
any components attached incorrectly when the C-TRAC2.1 has power turned off.
This is the result of a feedback voltage which may cause certain output signals to
stay energized. (E.g. It may keep a fan delay relay energized to keep fan running when
not required.)
V. HEAT OUTPUT
The C-TRAC2.1 has a 0-10 VDC output ramp from terminals "HD and B", which can be used to control gas
heat controls (DJM2, DJT2, G-TRAC, G-TRAC2, 109 Interface), electric heat (H-TRAC) or water coils, etc.
VI. SYSTEM TIMINGS
The C-TRAC2.1 has two built in timing circuits.
1. Timing from heat to economizer to mechanical cooling modes varies depending on the error between
calculated set point and actual discharge temperatures.
2.
Inter-stage minimum run and minimum off time for compressors is 4 minutes.
VII. DIP SWITCHES AND POTS
The C-TRAC2.1 uses a number of dipswitches and pots to set the parameters it will look at to set its control
set point at. They are set at the factory to "customize" the control for its particular application on each unit.
Changing any of these settings can destroy the control capability for your particular system.
Option 1. Discharge air control. (Only dipswitch 1 on.)
Option 2. Not used – for test purposes only. (Only dipswitch 2 on).
Option 3. Discharge air control with room or return air reset. (As the room warms up the discharge
temperature falls. Dipswitch 1 and 3 on, reset wired to "V, X, Y and Z").
Option 4. Discharge air control with ambient and/or VAV reset. As the airflow increases or the ambient
temperature increases the discharge temperature will be set downwards. (Dipswitch 1 and 4 on,
resistor network wired to "V, X, Y, and Z").
Option 5. Discharge air control with the BMS reset signal of 4-20 ma or 0-10 VDC modifying the
discharge temperature. (As the signal strength increases above 12 MA or 5.5 VDC the discharge
temperature is driven warmer; as the BMS signal falls below 12 MA, 5.5 VDC the discharge
temperature is driven colder. Dipswitch 1 and 5 on, BMS reset wired to + and -).
:
NOTE
At approximately 5.5 VDC or 12 ma input from the BMS there would be no reset occurring.
As the BMS input voltage deviates from this voltage, the C-TRAC2.1 will reset the
discharge up or down
The C-TRAC2.1 dipswitches will be set for operation as per the following table:
IOM-12
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C-TRAC2.1 MANUAL
March 1999 R1