3-Speed Adjustable; Variable Speed Fan; Outdoor Air Damper Operation - Daikin MicroTech Operation And Maintenance

3-Speed Adjustable

The UVC uses three defined PWM outputs to control the IAF
to low, medium, or high speed. When fan control is in the
Auto mode, the UVC adjusts the fan speed up and down in
an attempt to maintain the control temperature setpoint. The
fan capacity percentage required is calculated using a PI loop
comparing the control temperature and effective setpoint. The
fan speed increases when the capacity percentage required
is greater than or equal to the break point + the break point
differential defined in Table 16
Table 16: Fan Speed Break Points
Break Point Auto Low
Break Point Auto Medium
Break Point Auto High
Break Point Auto Differential
The fan speed decreases when the capacity percentage
required is less than the break point.
The fan speed signal used for low, medium, and high speed
is defined in Table 17 and can be field adjusted using the LUI
keypad or ServiceTools software. The application ensures that
low speed ≤ medium speed ≤ high speed and also prevent the
selection of a fan speed that is outside of the min/max range
for that fan setting.
If the UVC is configured for continuous fan operation, the fan
remains at low speed when no capacity is required.
Table 17: Ranges For 3 Speed Adjustable Fan
Fan Speed
PWM low fixed-speed
PWM medium fixed-speed
PWM high fixed-speed

Variable Speed Fan

The UVC uses a variable PWM output to control the IAF.
When fan control is in the Auto mode, the UVC adjusts the
fan speed up and down in an attempt to maintain the control
temperature setpoint. The fan capacity percentage required is
calculated using a PI loop comparing the control temperature
and effective setpoint.
www.DaikinApplied.com
.
5%
77%
95%
2%
Operating Range
50% - 80%
70% - 90%
80% - 100%

Outdoor Air Damper Operation

The UVC is configured for an OA damper operated by a
proportional actuator. The OA damper actuator contains a
spring that ensures the OA damper is closed upon loss of
power. The proportional actuator is controlled by a single
analog signal and a single binary on/off signal. The OA damper
typically is open to the current minimum position during the
occupied and bypass occupancy modes and closed during the
unoccupied and standby occupancy modes.
Minimum Position
This allows each unit to be field configured to provide the
amount of fresh air required to the space at each of the three
IAF speeds. For units with EC fan motors configured for variable
speed fan operation and no CO
position ramps linearly between the low speed minimum position
percent to the high speed minimum position percent as the
motor ramps linearly from minimum speed to maximum speed.
Table 18: Default OA Damper Minimum Positions
IAF speed
High
Medium
Low
NOTE: If the CO Demand Controlled Ventilation (DCV)
2
option is used, the UVC only uses the IAF high
speed OA damper minimum position regardless
of fan speed. The DCV function adjusts the OA
damper above this minimum as needed to maintain
CO setpoint.
2
35 OM 1280-2 • MICROTECH UNIT CONTROLLER
Description of Operation
, the OA damper minimum
2
Without CO With CO
2
20% 5%
25% 5%
30% 5%
2