Trane VUV Installation, Operation And Maintenance Manual page 116

Diagnostics and Troubleshooting
Table 69. Motor spins too fast or spins without any apparent speed request
Situation Probable Cause
Verify that the voltage jumper on the motor plug harness is absent for 208-230V units and 277V units. If the jumper is present for these
Motor not controllable
units, the motor electronics will be damaged, and the motor will not be controllable.
Fan speed request too low Verify that the fan speed request is not below 450 rpm.
Verify that the all binary inputs to the customer terminal blocks are of proper and consistent polarity.
• For CSTI units, the fan inputs and end device inputs on TB3 must receive signals that are 24 Vac with respect to the unit chassis.
• For Fan Speed Switch (FSS) units, that incorporate the Tracer® ZN/CSTI adapter board, all inputs to TB3 must be 24 Vac with respect to
Inputs not of consistent polarity
• For Tracer® ZN units, where there is a desire to use parallel fan inputs on the adapter board TB3 strip, the inputs must be COM (i.e., the
Note: Do not short 24 Vac (pos 1 or pos 2) to chassis; refer to the unit schematic.
Verify that variable speed (VSP) inputs are properly wired to 1TB4.
• Do not short the courtesy 10 Vdc supply to chassis or loads that require greater than 10 mA of DC current.
Failure of motor control board
• Please observe proper polarity of 0–10 Vdc inputs. Failure to observe proper polarity can cause failure of the VelociTach™ motor control
Verify that the signal on the VSP inputs is noise free. The VelociTach™ motor control board contains an adjustable noise floor
Output signals being ignored
parameter,
• If the customer supplied controller outputs signals that are below the noise threshold, they will be ignored by the ECM engine.
Verify that VSP input settings are correct. The motor control board board contains an adjustable digital amplifier,
Motor spinning too fast compensate for long 10 Vdc cable runs. For normalized (0–10 Vdc) signals, this setting should be set to 1.000. If it is set too high,
the motors will run faster than the requested ratio, and will hit the limit
Verify that
Motor not controllable
Replacing ECM Components
WARNING
Hazardous Voltage w/Capacitors!
Failure to disconnect power and discharge capacitors
before servicing could result in death or serious
injury.Disconnect all electric power, including remote
disconnects and discharge all motor start/run
capacitors before servicing. Follow proper lockout/
tagout procedures to ensure the power cannot be
inadvertently energized. Verify with a CAT III or IV
voltmeter rated per NFPA 70E that all capacitors have
discharged.
Replacement Guidelines
• ECM motors contain capacitors which store residual
energy. Please keep clear of the fan wheels for
five minutes after the power has been removed from the
system, as a power request with the motor powered off,
could result in a very short period of actuation. Unplugging
the motor is adequate to ensure that there will be no power
request.
• Configuration adjustments to the VelociTach motor in
accordance with the parameters that are printed on the
label adjacent to the VelociTach board. These parameters
reflect the factory settings for the unit. Subsequent
changes to parameters made during commissioning will
not be reflected in the printed parameters.
• Initial hookups to the CSTI and standard adapter board,
including low voltage interconnections, must be made with
the power off.
• Do not make connections to the motors or the adapter
boards while power is ON. Do not remove connections to
the motor or the adapter boards while the power is ON.
• Caution should be taken to stay clear of hazardous
voltages, moving parts and electric heat elements while
making adjustments to the VelociTach™ motor control
116
unit chassis.
inputs will honor only 0 V with respect to unit chassis).
board, the customer-supplied controller or the Tracer® ZN controller.
vflr
, that can be configured to reject signals below the noise floor.
M1Lo M2Lo
and
Ahm1
, the low motor signal output limits, are set correctly.
board. If it is not practical to stay clear of these areas
during adjustment, please contact Trane Global Parts for
configuration kit that allows easy powering of the engine
board outside of the unit with a 9V battery.
• For safe operation, it is necessary to configure
replacement boards to match the setup/switch
configuration of the previously installed boards.
• Ensure that new circuit modules are firmly seated on the
nylon standoffs, and that the nylon standoffs are firmly
seated on the metal panel
• Ensure that drip-loops are maintained on wiring on pipe
end of unit to avoid wicking of water into the unit.
• Before assuming that any of the boards or components in
the new system have failed, please ensure that the
VelociTach™ motor control board has been configured
correctly and that the switches on the CSTI board (where
applicable) are set correctly.
• It is necessary to configure the service replacement
VelociTach™ motor control board before commissioning
the unit. The board is pre-configured with safe values, but
will NOT work correctly unless properly configured. The
factory shipped parameter settings are on the label
adjacent to the VelociTach™.
• Only genuine Trane replacement components with
identical Trane part numbers should be used.
• Unit fan assemblies contain concealed wires that should
be removed before the fan-board is removed, to avoid
nicking the wire.
• Care should be maintained to retain the order of the motors
with respect to the motor plugs. On a unit with two motors,
the double-shafted motor will always be to the left side, and
will be designated as Motor 2 by the controller.
AiSc
before the input voltage has reached its upper limit.
UV-SVX005G-EN
, to