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Figure 22. SCR (top) and internal potentiometer
(bottom)
Max
120 v
208 v–
277 v
347 v
DO NOT SET THIS
POTENTIOMETER
BELOW THE VOLTAGE
OF THE FAN MOTOR.
N N o o t t e e : : Do not set this potentiometer below the voltage
of the fan motor.
Electrically Commutated Motor
(ECM)
Figure 23. ECM control board – Non-modulating
control with Trane unit controller (excludes Tracer®
UC210 and UC400) or non-Trane unit controller
Trane offers an energy efficient ECM as a motor option.
The optional Tracer® UC210 and UC400 unit controllers
directly interface with the ECM to control fan airflow
and fan on/off control. Other Trane and non-Trane unit
controller options require an ECM control interface
(shown in
Figure 23, p.
33) to set fan airflow while the
unit controller dictates fan on/off control via a binary
output. The manual potentiometer is used to set the
percent-on or speed. The ECM control interface
contains display, which can be used to view percent-on
setting and speed.
VAV-SVX08R-EN
N N o o t t e e : : This feature only verifies airflow is set properly. It
does not indicate actual ECM speed. The ECM
must be load tested. The ECM must be
connected to the fan to properly test the ECM
and display fan speed.
The following tables provide mapping from fan
percent-on setting to fan airflow for each fan type and
size. Additional fan settings can be determined by
interpolating from the tables or using the following
equation:
•
Airflow setting = Airflow min + {(Potentiometer
Setting) x [(Airflow max - Airflow min)/100]}
Figure 24. ECM control board – Modulating control
with non-Trane unit controller
An alternate ECM interface (shown in
is utilized on unit with Non-Trane unit controller
including factory mounted third-party unit controllers.
This ECM interface allows fan modulation and fan on/
off control from the unit controller. There are two input
signal options as well as a temporary adjustment via
manual potentiometer.
•
0-10 VDC modulation signal with separate on/off
binary signal.
•
2-10 VDC modulation signal where the ECM starts
at a rise to 2 VDC and stops at a fall to 1 VDC.
N N o o t t e e : : 2-10 VDC input signal requires the shunt to be
installed on the "P" terminals as shown in
25, p.
33.
Figure 25. ECM control board 2-10 VDC input signal
shunt placement
The ECM control interface contains two diagnostic LED
indicators, motor RPM (speed) and Motor Speed
Request. Motor RPM indicates the motor is driven and
running when lit. Motor Speed Request, represents the
percentage of the requested motor speed being
U U n n i i t t S S e e t t u u p p
Figure 24, p.
33)
Figure
33
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