■ STANDSTILL:
The inlet valve is closed. The minimum pressure/check valve shuts off the oil separator from
the distribution network. The venting valve is open.
The compressor motor is stopped.
■ MODULATING CONTROL:
With the help of a control valve (the proportional controller) the degree of opening of the inlet
valve is steplessly varied in response to the air demand. The airend delivers compressed air to
the distribution network.
The load and power consumption of the drive motor rises and falls with the air demand.
The regulating valve is factory set. The setting should not be changed without consultation with
KAESER SERVICE.
4.6.2 Control modes
Using the selected control mode, the controller switches the machine between its various opera‐
tional states in order to compensate for air being drawn of by consumers and maintain system
pressure between the set minimum and maximum values. The control mode also rules the degree
of energy efficiency of the machine.
The machine-dependant venting phase between the LOAD and STANDSTILL operating modes en‐
sures load changes at minimum material stresses.
The controller SIGMA CONTROL BASIC can operate in the following modes:
■ DUAL
■ QUADRO
■ MODULATING control
Energy-efficient control modes for various applications:
Application
Recommended
control mode
Compressed air station with one machine or several machines with com‐
parable delivery
QUADRO
Machine for peak load in a compressed air station
DUAL
Machine for intermediate load in a compressed air station
QUADRO
Machine for basic load in a compressed air station
QUADRO
Tab. 38 Energy-efficient control modes
The SIGMA CONTROL BASIC controller is factory set to QUADRO control mode unless specifi‐
cally ordered otherwise.
DUAL
In the DUAL control mode, the machine is switched back and forth between LOAD and IDLEto
maintain the machine working pressure between the preset minimum and maximum values. When
maximum pressure is reached, the machine switches to IDLE. When the preset
idling time
has
elapsed the machine is STOPPED.
The
idling time
is permanently set in SIGMA CONTROL BASIC .
4
Design and Function
4.6
Operating modes and control modes
9_5717 20 E
Service Manual Screw Compressor
ASK T SIGMA CONTROL BASIC
31
Option C1
Option C1
