Application Notes - Trane BCHE Installation, Operation And Maintenance Manual

Diagnostics and Troubleshooting
Figure 106. CSTI wiring
Adapter board
Attach green wire to
quick-connect terminal
Green wire
Attach green wire
to white plug
VelociTach
engine control
board
4. Ensure that the new VelociTach motor board controller
is configured to match the configuration label that is
present on the unit. It is necessary to configure the
VelociTach board to avoid improper operation of the
unit, discomfort to the end user, and loud fan operation.
Figure 107. Configure VelociTach board
5. Ensure that the CSTI adapter board switches are set
correctly, as indicated in the unit schematic (where
applicable) shown in the following figure.
142
Figure 108. Ensure CSTI adapter board switches
are set correctly
6. After replacing modules, commission the unit by
performing at a minimum,
Verification," p. 100.

Application Notes

The ECM motor has some notable differences to traditional
designs.
RPM Mode
The motors are programmed from the factory to run in rpm
mode and will not change rpm based on external static
pressure, except at the performance limits of the motor/
controller. The units are shipped with the rpm set to the
selected value for High. The speeds can be changed for
high, medium, and low operation, but should not be
changed for the electric heat actuation speeds.
Generally, the fans deliver less cfm for the same rpm, if the
static is increased and the power will decrease. The fan will
deliver more cfm for the same rpm, if the static is
decreased and the fan power will increase. A unit with high
static configuration should not be used to free-deliver air (i.
e., with no ducting attached).
Field Power Wiring
This motor uses an electronic variable speed motor control,
which includes a line reactor to minimize power line
harmonic currents. It is recommended that good wiring
practices be followed to manage building electrical power
system harmonic voltages and currents to avoid electrical
system problems or other equipment interaction.
Performance Boundaries
While the speeds of the fan motors can be adjusted, never
program a fan speed outside the operating limits for the
given unit size. In many cases, units configured for high-
static operation will not achieve the desired rpm if the ESP
of the unit is too low, or the unit is allowed to "free-
discharge." The VelociTach motor control board contains
settings that will limit the output power of the motor under
"Fan Speed Response
BCX-SVX002A-EN