Setpoint Reset Of The Chilled Water - Daikin EWWQ-AJYNN Service Manual

Functional Control
2.4

Setpoint Reset of the Chilled Water

1
Introduction
2
Double setpoint
3
4
5
External signal
2–54
Among the MicroTech NC controllers options, there are also several possibilities to regulate the unit
with particular logics or outside signals. The setpoint reset function gives the possibility to modify the
local setpoint of the chilled water according to the following logics:
■ double setpoint
■ external signal
■ OAT (outdoor ambient temperature) reset
■ return water reset
Through an external contact (optionally a switch is installed on the electric panel control), it is possible
to vary the local setpoint of control between two well defined values. Such option results are
advantageously applicable in case of installation with ice bank. When the temperatures of evaporator
outgoing water are inferior to 4°C, the introduction of the correct quantity of Anti-freeze in the hydraulic
system is required.
Enable Double
Setpoint
Cooling Double
Setpoint
Heating Double
Setpoint
The setpoint override allows, by use of an external signal, to override the chilled water setpoint.
This function is activated by enabling the analog input B3 of the controller. A 4-20mA signal can be
used to change the setpoint.
Setpoint
Setpoint +
diff.
Setpoint
■ For inputs lower than 4mA, the water setpoint is set to the local setpoint
■ For inputs between 4 and 20mA, the setpoint is obtained by linear interpolation between the
setpoint and the setpoint + setpoint diff (entered in the user menu)
■ For inputs higher than 20mA, the water setpoint is set to setpoint + diff.
Remark: The value entered for the setpoint diff can also be negative.
Y
12.0 ˚C
- - - - ˚C
4mA
Setpoint
diff.
Input signal
20mA
Part 2 – Functional Description
ESIE07-05