A C-TRAC3
14 of 21 Jan 13 R5
This is a calculated increase meant to compensate for a reduction in total airflow, not a measured actual
value.
External controls are required to disable the mechanical cooling and heating if the VFD has been switched
to bypass mode, due to VFD failure.
If the C-TRAC3 is configured for variable airflow systems, the minimum position pot is factory sealed at the
fully counter-clockwise position, as the input will interfere with the VFD minimum speed setting.
Adding a variable air volume system to equipment originally designed with
constant air flow will void warranty, unless approved and recorded by Engineered
Air.
WIRING
The C-TRAC3 terminals H and N require a minimum 24 Vac, 40 VA class 2 power supply that does not need
to be isolated from the rest of the systems components. The C-TRAC3 incorporates an internal ½ wave
rectified power supply that has the DC common virtually the same as the AC’s neutral supply (within
0.05Vdc).
Terminal N should be wired to the common of the same source supplying power to terminals E, A, and K.
All remote wiring attached to terminals Q, U, X, Y, V, Z, + and - should be installed in a clean (no electrical
noise) environment. Wire size should be a minimum of 24ga. twisted pair to reduce electrical noise
(shielded wire is recommended). For longer runs (over 50 ft. eq. length), the use of a minimum
20 gauge-shielded wire is recommended. The shield should be grounded at the unit end only, with the
other end taped.
It is important to ensure correct polarity when wiring into the system.
The modulating output signals from the C-TRAC3 can be programmed for other voltage ranges if needed
for operating other controls. The minimum load resistance is 500 Ohms. The possible variable voltage
ramps are:
0 – 10 VDC
0 – 7 VDC
0 – 5 VDC
0 – 2 VDC
As noted, these are configured values and the selected value is noted in the unit function sheet.
If the BMS input terminals (+ and -) are included as part of the unit function and are not field wired, the
signal is considered as being zero, therefore the control will operate as described when this signal is low
(ex maximum cooling).
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