Specifications

1 = VLT HVAC Basic Drive
2 = Star/delta starter
3 = Soft-starter
4 = Start directly on mains
2.5.8 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
two different systems. In the example on the following
page, the two systems can be established at roughly the
same price.
2.5.9
Without a Frequency Converter
D.D.C. =
Direct Digital
Control
E.M.S. =
Energy
Management
system
V.A.V. = Variable Air Volume
Sensor P = Pressure
Sensor
T
= Temperature
Table 2.1 Fan System made in the Traditional Way
M
- +
M
M
x6 x6
x6
175HA205.12
Valve
posi-
tion
Starter
Fuses
LV
supply
P.F.C
Flow
3-Port
valve
Bypass
Return
Control
Supply
air
V.A.V
outlets
Duct
P.F.C
Mains
Fuses
Starter
Bypass
supply
LV
Return
valve
3-Port
Flow
Control
Valve
posi-
tion
Starter
Power
Factor
Correction
Mains
IGV
Mechanical
linkage
and vanes
Fan
Motor
or
actuator
Main
B.M.S
Local
D.D.C.
control
Sensors
PT
Pressure
control
signal
0/10V
Temperature
control
signal
0/10V
Control
Mains
Cooling section Heating section
Fan sectionInlet guide vane
Pump Pump
Introduction to VLT HVAC Ba... VLT HVAC Basic Drive Design Guide
14 MG.18.C2.02 - VLT
®
is a registered Danfoss trademark
22