TM_s-MEXT_ME28relC_00_12_19_EN
Technical manual
TRANSLATION OF THE ORIGINAL INSTRUCTIONS
86
10.5
AUTOMATIC SPEED REGULATION FUNCTION
This function allows to automatically adjust EC radial fan speed. It may follow two logics:
•
Constant flow rate regulation.
•
Constant residual ∆P regulation.
For these two logics, a differential pressure transducer is used and positioned so as to detect the pressure value used for regulation.
10.5.1
Constant flow rate regulation
The pressure transducer detects the pressure difference on the fan outlet, as shown in the figure below:
Figure 10-3:
Chart for positioning the pressure taps for the differential pressure sensor
After acquiring the ∆P it is compared with the setpoint derived from the following function:
2
2
2
2
k
n
Q
k
Q
P
t
set
=
=
Where:
•
Q
set
= desired calculated flow setpoint.
•
Q
t
= flow setpoint entered from the keypad.
•
n = Number of fans.
•
k = Characteristic value of the measurement inlet (varies according to the diameter).
The following table shows the k value associated to each diameter and type of outlet used in s-MEXT units.
This value can be set by changing parameter P11.03.
Value P11.03
k
Type
Fan models
0
155
dn355
R3G 355-AM29 -71
4
112
dn310 Vpro-ZH
RH31V-6IK.BD.1R
7
445
dn630 Vpro-ZH
RH63V-ZIK.GG.1R
RH63V-ZIK.GL.1R
The controller adjusts following the chart below.
DIMINUZIONE Portata
P23.65
AUMENTO Portata
Pressione differenziale
NESSUNA Azione
Differenziale
P23.05
Differenziale
P23.66
Figure 10-4:
Fan adjustment graph
The Diff. press set is derived from the above formula.
INCREASE flow
NO action
DECREASE flow
Differential
Differential
Differential pressure
