Danfoss FC 102 Design Manual page 25

Introduction to VLT® HVAC D...
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1
0
0 12,5
Illustration 2.14 A Frequency Converter Does Not Consume
More Than Rated Current
®
1 VLT HVAC Drive
2 Star/delta starter
3 Soft-starter
4 Start directly on mains
Table 2.8 Legend to Illustration 2.14
2.7.9 Using a Frequency Converter Saves
Money
The example on the following page shows that a lot of
equipment is not required when a frequency converter is
used. It is possible to calculate the cost of installing the 2
different systems. In the example on the following page,
the 2 systems can be established at roughly the same
price.
2.7.10 Without a Frequency Converter
Direct Digital
D.D.C. =
Control
V.A.V. = Variable Air Volume
Sensor P = Pressure
Table 2.9 Abbreviations used in Illustration 2.15 and Illustration 2.16
MG11BC02
Design Guide
4
3
2
25 37,5 50Hz
Full load
& speed
Energy
E.M.S. = Management
system
Sensor
= Temperature
T
Danfoss A/S © Rev. 06/2014 All rights reserved.
Cooling section Heating section Inlet guide vane
- +
Return
Flow Flow
Return
Control Control
3-Port 3-Port
valve
valve
Valve Mechanical
Valve
posi- linkage
posi-
tion and vanes
Bypass Bypass tion
IGV
Motor
Pump Pump
M M
or
actuator
x6 x6
Starter Starter
Control
Fuses Fuses
LV LV
supply
supply
P.F.C
P.F.C
Mains Mains
Illustration 2.15 Traditional Fan System
2.7.11 With a Frequency Converter
Cooling section Heating section
Fan section
Fan
- + M
Return Flow Return Flow
Pump Pump
M M
x3 x3
VLT VLT VLT
Control
Control
temperature
temperature
0-10V
0-10V
or
or
0/4-20mA
0/4-20mA
Mains Mains
Mains
Illustration 2.16 Fan System Controlled by Frequency
Converters.
Fan section
Supply
air
Fan
V.A.V
M
Sensors
outlets
PT
x6
Duct
Local
Main
D.D.C.
B.M.S
control
Starter
Temperature
control
signal
Pressure
0/10V
Power control
signal
Factor
0/10V
Correction
Mains
Supply
air
V.A.V
Sensors
T outlets
P
x3
Duct
Local
Main
D.D.C.
B.M.S
control
Pressure
control
0-10V
or
0/4-20mA
23
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