External Discharge Air Reset Signal; External Outdoor Air Damper Reset Signal - Daikin MicroTech II Installation And Maintenance Manual

Field Wiring

External Discharge Air Reset Signal

The discharge air temperature set point on DAC units can be
reset by an external voltage or current signal applied to analog
input MCB-AI2. The external reset method can be selected at
the controller keypad. External reset requires a field supplied
reset signal in the range of 0–10 VDC or 0–20 mA wired to
terminals 132 and 133 on the field terminal block (TB2). Refer
to the unit wiring diagrams or Figure 16 on page 38 for wiring
termination details.
Ground loop current hazard. Can cause equipment
damage.
Isolate the external reset signal from any ground other than
MicroTech II controller chassis ground. If not isolated, ground
loop currents can occur, causing damage or erratic unit
operation. The device or system providing external reset signal
must be connected to the MicroTech II controller chassis, or it
must be providing an isolated output. If not, condition the signal
with a signal isolator.
If the external reset option is selected, the controller linearly
resets the cooling and heating discharge air temperature set
points between user-programmed minimum and maximum
values as the field supplied reset signal varies from a minimum
to maximum (or maximum to minimum) value.
Field wire the external reset signal to the unit using a twisted
pair, shielded cable (Belden 8761 or equivalent). Cable with 22
AWG conductors is sufficient.
Do not install this cable in the same conduit as power wiring.
Such installation can cause unit malfunction.
Note – If the field signal is in the 0–10 VDC range, configure the
analog input jumper associated with analog input MCB-
AI2 in the no-jumper (NJ-VDC) position. The analog
input DIP switch for this input then must be in the ON (V)
position. If the field signal is in the 0–20 mA range,
configure the jumper in the current (2-MA) position. The
analog input DIP switch for this input then must be in the
OFF (T) position.
Detailed information regarding discharge air temperature reset
is located in the "Discharge Set Point Reset" section of the
applicable operation manual (see Table 1 on page 1).
16
CAUTION
CAUTION

External Outdoor Air Damper Reset Signal

Ground loop current hazard. Can cause equipment
damage.
Isolate the external reset signal from any ground other than
MicroTech II controller chassis ground. If not isolated, ground
loop currents can occur, causing damage or erratic unit
operation. The device or system providing external reset signal
must be connected to the MicroTech II controller chassis, or it
must be providing an isolated output. If not, condition the signal
with a signal isolator.
On units equipped with a 0–100% modulating economizer but
not equipped with the optional Design Flow outdoor air
measuring option, the minimum outside air damper position
set point can be reset by an external voltage or current signal
applied to analog input MCB-AI7. The external reset method
can be selected at the controller keypad. External reset requires
a field supplied reset signal in the range of 0–10 VDC or
0–20 mA wired to terminals 124 and 125 on the field terminal
block (TB2). Refer to the unit wiring diagrams or Figure 18 on
page 42 (SCC units) for wiring termination details.
If the external reset option is selected, the controller linearly
resets the outside air damper position set point between user-
programmed minimum and maximum values as the field
supplied reset signal varies between a minimum and maximum
(or maximum to minimum) value.
The external reset signal must be field-wired to the unit using a
twisted pair, shielded cable (Belden 8761 or equivalent). Cable
with 22 AWG conductors is sufficient.
Do not install this cable in the same conduit as power wiring.
Such installation can cause unit malfunction.
Note – If the field signal is in the 0–10 VDC range, configure the
analog input jumper associated with analog input MCB-
AI7 in the no-jumper (NJ-VDC) position. The analog
input dip-switch for this input then must be in the ON (V)
position. If the field signal is in the 0–20 mA range,
configure the jumper in the current (2-MA) position. The
analog input dip-switch for this input then must be in the
OFF (T) position.
Detailed information regarding outside air damper position
reset can be found in the "Economizer" section of the
applicable operation manual (see Table 1 on page 1).
CAUTION
CAUTION
Daikin IM 696-4