Air System; Internal Air Fans; Flow Rate Sensor For Fans - Daikin UATYA-BBAY1 Manuel D'installation, D'utilisation Et D'entretien

4.7 Air system

4.7.1

Internal air fans

Depending on the configurations, there may be only supply fans or also return fans in the units.
The fans are radial fans with reverse blades, with external rotor motor directly coupled to the impeller.
The radial fans are called "EC", with electronically commutated brushless motor. The fan is powered by mains AC
voltage, and speed control is obtained via DC 0-10V control signal coming from the microprocessor installed on the
unit. This makes it possible to set the air flow rate through the parameter being displayed.
The motors have alarm signalling, which includes thermal overload protection, overcurrent, undervoltage, absence
of one or more phases and seized rotor.
The EC fans are not provided with a contactor and are constantly live as soon as the main disconnect
switch of the unit is closed.
4.7.2

Flow rate sensor for fans

Units with "EC" fans are provided with a differential pressure transducer that detects the pressure difference between
the inside and the outside (upstream) of the intake nozzle. The air flow rate is proportional, for each fan/nozzle pair,
to the square root of the pressure difference according to the equation:
where
- Q = total air flow [m3 / h]
- n = number of fans in the unit
- k = constant according to the fan nozzle
- ΔP = pressure difference measured on the nozzle [Pa]
The differential pressure value and the air flow rate can be shown directly on the display of the microprocessor that
carries out automatic control of the air flow rate.
We reserve the right to make changes without any prior notice.
UATYA
4P645202-2
Translation from original instructions
Packaged Rooftop
31