Page 3 - AV-series

AV-series frequency control

PLANT DEMAND FOR COMPRESSED AIR A plant’s demand for compressed air
Output % varies throughout the day - from zero
100 demand to peak demand.
Conventional screw compressors
are not able to switch between
50 operating modes according
to a plant’s current demand
for compressed air. Owing to
constant switching between
loading/unloading modes or the
0 6 12 18 24 idle running of compressors,
Monday–Friday Saturday Sunday conventional screw compressors
consume consistently large
amounts of electrical energy when operating. The Comprag AV compressor series with frequency control has been
created for economical compressor operation where there is varying demand.
AV compressors are provided
OPERATING COST OF COMPRESSOR with a frequency converter for
11% % 16 % Investment in purchase continuous control of compressor
16%
11
8%
10% % 8% Servicing output according to the current
10
demand for compressed air. They
Commissioning provide a plant with the necessary
1%
1%
1% 1%
Energy consumption amount of compressed air at a
78
50
78% % 50% % given moment and at a constant
Saving set pressure, while consuming only
25% in electrical as much electrical energy as there
energy
is demand for compressed air. This
COMPRESSOR without COMPRESSOR COMPRAG with mode of operation conserves as
frequency control frequency control much energy as possible.
Comprag compressors with frequency control allow a 25% saving in electrical energy consumption.
Mechanism of compressor with frequency control:
Varying compressed-air demand involves a change in pressure in a plant’s compressed-air system. A pressure sensor installed
in the compressor brings about a change in system pressure by means of a corresponding signal sent to the compressor’s
controller. Via the frequency converter, the controller sets a speed for the electric motor to match the compressor’s required
output. In this way, the plant’s compressed-air system pressure is kept at a constant value.
The frequency converter means that
CURRENT FOR DIFFERENT STARTING CIRCUITS OF AN INDUCTION MOTOR compressor start-up is associated
with very low starting currents. This
% Nominal current 600 Soft starter Star-delta switching life of the electrical motor and the
has a positive effect on the service
800
electrics.
Frequency converter
Direct starting
400
200
0
2 4 6 8 10 12 14 16 18 20 22 24 26 seconds
www.comprag.com STATIONARY SCREW COMPRESSORS AV-SERIES 3