Danfoss VLT HVAC Basic Drive FC 101 Programming Manual page 95

Parameters
3.15.6 22-8* Flow Compensation
In certain applications, it is not possible for a pressure transducer to be placed at a remote point in the system, and it can
only be placed close to the fan/pump outlet. Flow compensation operates by adjusting the setpoint according to the output
frequency, which is almost proportional to flow. Thus, it compensates for higher losses at higher flow rates.
H (required pressure) is the setpoint for closed-loop (PI) operation of the frequency converter and is set as for closed-
DESIGN
loop operation without flow compensation.
Illustration 3.17 Flow Compensation Set-up
There are 2 methods which can be employed, depending on whether the speed at system design working point is known.
Parameter used
Parameter 22-80 Flow Compensation
Parameter 22-81 Square-linear Curve Approximation
Parameter 22-82 Work Point Calculation
Parameter 22-84 Speed at No-Flow [Hz]
Parameter 22-86 Speed at Design Point [Hz]
Parameter 22-87 Pressure at No-Flow Speed
Parameter 22-88 Pressure at Rated Speed
Parameter 22-89 Flow at Design Point
Parameter 22-90 Flow at Rated Speed
Table 3.12 Speed at Design Point Known/Unknown
MG18B502
Programming Guide
Speed at design point
Danfoss A/S © 04/2018 All rights reserved.
Speed at design point
KNOWN UNKNOWN
+
+
+
+
+
+
-
-
-
3 3
+
+
+
+
-
+
+
+
+
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