ECM Motors
150
UNT-SVX07E-EN
Typical equipment and controls design practice will
ensure that the fans will come on if there is a call for heat,
cool, or ventilation. In most cases, we will depend on the
controller/thermostat to call for the fan to come on when
appropriate, but during calls for electric heat, or calls for
heat on CSTI units equipped with electric heat, as a call for
the appropriate fan speed. This behavior, as described
previously, is an indirect request.
When a call for electric heat is made, the system will
positively drive the fan on to the correct speed, regardless
of whether the controller has asked for fan operation or
not. The unit design incorporates an interlock instead of a
lock-out. (It does not lock out electric heat if the fan is set
to off; it brings the fan on.)
Notes:
In many cases, indirect requests will result in fan
behavior change regardless of whether the end-
device fails to actuate (due to device failure, or
safety/down-stream lockouts). If there is hot
water available on CSTI units with changeover
coils and electric heat, we will still drive the fan
to the appropriate electric heat speed.
Notes:
The new fan coil designs incorporate
sophisticated fan interlocks that will lockout heat
if there is a fan failure.
If the preceding conditions do not describe the behavior of
the unit, the following checks should be performed:
Motor has been locked out
due to overspeed or runaway
condition
Motor 1 has an overspeed condition. The “Status Display”
will be interrupted to display:
→
→
• Ensure that set-screw is attached firmly to the motor
shaft.
• Ensure that motor plugs and all plugs to adapter boards
and the ECM engine board are secure.
• Verify that the configuration does not specify a speed
lower than 450 rpm for the affected motor. Speeds
below 450 rpm are not supported on fan-coil units.
VSP Inputs (0–10V inputs)
are of the wrong polarity
Variable speed (VSP) inputs may not be 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.
• Observe proper polarity of 0–10 Vdc inputs. Failure to
observe proper polarity can cause failure of the
VelociTach motor control board, the customer-supplied
controller, or the Tracer ZN controller.
Customer Controller output
signal to VSP Inputs are too
low.
Note:
If the customer supplied
controller outputs
signals that are below
the noise threshold, they
will be ignored by the
ECM Engine.
Noise floor is set too high.
• The VelociTach motor control board contains an
adjustable noise floor parameter,
that can be
configured to reject signals below the noise floor.
• The noise floor parameter is set too high, it can be
lowered as long as there are acceptable noise levels on
the inputs lines.
Table 94. Motor does not spin, spins too slowly
Situation
Probable Cause
Solution
Table 95. Motor spins too fast or spins without any apparent speed request
Situation
Probable Cause
Motor not controllable
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 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. Speeds below 450 rpm are not supported on the fan coil
product.
Inputs not of consistent
polarity
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 unit chassis.
• 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 inputs will honor only 0 V with respect to unit chassis).
Note:
Do not short 24 Vac (pos 1 or pos 2) to chassis; refer to the unit schematic.
Failure of motor control board
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.
• Please observe proper polarity of 0–10 Vdc inputs. Failure to observe proper polarity can cause failure of the
VelociTach motor control board, the customer-supplied controller or the Tracer ZN controller.
Output signals being ignored
Verify that the signal on the VSP inputs is noise free. The VelociTach motor control board contains an adjustable noise
floor parameter,
, that can be configured to reject signals below the noise floor.
• If the customer supplied controller outputs signals that are below the noise threshold, they will be ignored by the
ECM engine.
Motor spinning too fast
Verify that VSP input settings are correct. The motor control board board contains an adjustable digital amplifier,
, to 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
before
the input voltage has reached its upper limit.
Motor not controllable
Verify that
and
, the low motor signal output limits, are set correctly.
