Automatic Speed Regulation Function; Constant Flow Rate Regulation - Mitsubishi Electric s-MEXT-G00 006 Technical Manual

TM_s-MEXT_ME28relC_00_12_19_EN
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:
After acquiring the ∆P it is compared with the setpoint derived from the following function:
Where:
•
Q = desired calculated flow setpoint.
set
•
Q = flow setpoint entered from the keypad.
t
•
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
The controller adjusts following the chart below.
INCREASE flow
AUMENTO Portata
The Diff. press set is derived from the above formula.
Technical manual
Figure 10-3: Chart for positioning the pressure taps for the differential pressure sensor

P
k
0 155
4 112
7 445
NO action
NESSUNA Azione
Differential
Differenziale
P23.05
Figure 10-4: Fan adjustment graph
2
 
Q
 
t
2
 
n
Q
= =
set
2 2
k k
Type
dn355
dn310 Vpro-ZH
dn630 Vpro-ZH
DIMINUZIONE Portata
P23.65
Differential
Differenziale
P23.66
86
Fan models
R3G 355-AM29 -71
RH31V-6IK.BD.1R
RH63V-ZIK.GG.1R
RH63V-ZIK.GL.1R
DECREASE flow
Pressione differenziale
Differential pressure
TRANSLATION OF THE ORIGINAL INSTRUCTIONS