Trane BCHE Installation, Operation And Maintenance Manual page 93

WARNING
Safety Alert!
Failure to follow instructions below could result in
death or serious injury.
In addition to the following tasks, you MUST:
• Follow all instructions in the unit's Installation,
Operation, and Maintenance manual, including
warnings, cautions, and notices.
• Perform all required tasks in any applicable
Service Alerts and Service Bulletins.
• Review and understand all information provided
in Submittals and Design Specifications.
CAUTION
Burn Hazard!
Failure to follow this instruction could result in the
unit overheating and becoming hot to the touch,
which could result in minor or moderate injury, and/or
equipment damage.
On electric heat units, certain parameter values are
locked out to prevent overheating of the unit. These
functions will appear to be saved; however, they will
not be accepted if the Electric Heat Protection setting
is "On". Do not change the Electric Heat Protection
setting to "Off" and make changes to the protected
settings unless you are programming an
unconfigured service replacement board to match the
unit settings on a ECM configuration label.
NOTICE
Equipment Damage!
Failure to follow instructions below could result in
equipment damage.
• A single 24 Vac supply system must be used.
• Ensure proper polarity and grounding when
connecting the 0 to 10 V system.
Note: Configuration adjustments to the motor control board
should be made through the SMALLER of the two
low-voltage lids on the front of the control panel,
through the low-voltage insulation/shielding.
• The 0–10V (variable speed) inputs are available for
use, but are not mandatory. The ECM system comes
standard with three to five field-accessible thermostatic
inputs (with adjustable speed), so the use of the 0–10V
inputs is optional.
• All inputs are independently configurable and
simultaneously accessible, and the motor control board
will choose the highest user (configured and requested)
speed. However, care should be taken with customer
controls to avoid contention of signals.
BCX-SVX002A-EN
ECM Overview and Setup
The motor control board and adapter boards offer
standard, normalizing 0–10V Variable speed fan inputs for
use with field supplied controllers or thermostats. These
inputs can be used as the only input to the system, used in
addition to the thermostatic (H, M, L) inputs, or not used at
all. The inputs are accessible via 1TB4 on the adapter
boards.
The motor control board is factory configured to drive the
unit to a minimum speed (catalogue "low speed" value),
defined as A A l l M M 1 1 and A A l l M M 2 2 once the analog (0–10V) input is
honored. As a default, the noise floor/threshold is set to
3 percent (0.3V). At 0.3V, the system will drive the motors
to the speeds defined in defined as A A l l M M 1 1 and A A l l M M 2 2 . If the
analogue input goes to 10V, the motor control board will
drive the motor to maximum speed (normally catalogue
"high speed" value), defined as A A h h M M 1 1 and a a h h m m 2 2 , and will
change speed in response.
Although the VelociTach motor control board ships with
settings that will work with most 0–10 VDC outputs,
calibration should be performed to maximize response
range and controller authority. Typically, the only settings
needed for the VSP inputs are calibration of the signal to
ensure that the system obeys the following rules:
• The minimum output from the field supplied controller is
met with a positive fan response. That is, we do not
want the v v f f l l r r setting on the motor control board to be
higher than the minimum output of the field supplied
controller, as the motor control board will "ignore" a
portion of the usable range of the customer fan variable
speed output.
• The minimum output from the field supplied controller is
not significantly greater than the floor setting v v f f l l r r floor.
If the minimum output of the controller is significantly
greater than the floor setting, the first point that the
motor will turn on will be above the A A l l M M 1 1 and A A l l M M 2 2
value. The full range of motor control will not be fully
utilized in this case, as the motor will never reach the
low speed motor analogue input scaling value for
Motor 1 and Motor 2 (A A l l M M 1 1 and A A l l M M 2 2 )
• The maximum output of the controller needs to be 10V,
or if lower, needs to be compensated using the analog
input scaling value, A A i i s s c c to normalize the operational
range. As a default, the scaling value is set to 1.00 (so
a voltage of 5V will be graded as 5V); however, to
compensate for long runs or lower max voltages (i.e.,
lower than 10.00), the scaling value can be increased
accordingly to maximize operational range.
For example, if the voltage is only reaching a value of
9.0V at the adapter boards, then the A A i i s s c c parameter
should be set to (10/9=) 1 1 .1 1 1 1 1 1 1 1 . If left un-calibrated, the
unit will never attain maximum speeds, defined as A A h h M M 1 1
and A A h h M M 2 2 .
• The motor control board can accept slightly over-biased
inputs up to 12 VDC, and the A A i i s s c c parameter can be
set to a value less than 1.0 to compensate.
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