Trane VUV Installation, Operation And Maintenance Manual page 118

Diagnostics and Troubleshooting
Figure 93. Ensure CSTI adapter board switches are set
correctly
6. After replacing modules, commission the unit by
performing at a minimum,
Verification," p. 69.
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
118
"Fan Speed Response
limit the output power of the motor under these overload
conditions. If the motors cannot achieve rpm close to the target
for a specific period of time, the unit will disable electric heat
and fan-status indicators.
MCA/MOP and Power Draw
ECM motors have variable output but are shipped at specific
settings to deliver proper performance and reliability. The
power draw indicated in the catalog indicates the power
consumed when applied properly (as shipped and with the
nominal ESP applied). However, the nameplate of the unit
indicates the maximum input draw of the motor, as the motor
settings can be changed to draw more power.
Electric Heat Relays
For quiet operation, the new BLDC units employ power relays
instead of definite purpose contactors for electric heat
actuation. The coils of multiple relays are hooked in parallel to
simulate a multi-pole contactor, as shown in
Two sets of three relays are used to perform the function of a
two 3-pole contactors.
Figure 94. Sample arrangement: electric heat relay
Troubleshooting Other Unit Functions
In some cases, the normal or abnormal operation of the ECM
may interact with other components in the system. Generally,
verification of the engine and adapter boards' wiring and
configuration should be checked if there are unexplained
abnormalities in other areas of the unit:
• Valve operation
• Electric heat operation
• Changeover sensor operation
• Damper operation
• Condensate overflow switch
A high degree of protection is provided on electric heat units.
If electric heat fails to actuate, it may be because of one of the
following events:
• Fans are failing to meet target speed. If a second motor is
not present, all settings for speeds for Motor 2 should be
set to 0000.
• Hot water may be available in the changeover coil.
• The connection to analogue input 1 on the Tracer® ZN
controller may be reversed in polarity.
• Target speeds for motors may be set too high:
FPRV
– The parameter may be set incorrectly.
AiPU
– The parameter may be set incorrectly.
Figure 94, p. 118.
UV-SVX005G-EN