4.7 Operating modes and control modes
4.7.1 Operating modes
The machine operates in the following modes:
■ LOAD:
The inlet valve is open. The airend delivers compressed air to the distribution network.
The drive motor runs under full load.
■ IDLE:
The inlet valve is closed. The minimum pressure/check valve shuts off the oil separator from the
distribution network. The oil separator tank is vented.
A small volume of air circulates through the bleed hole in the inlet valve, through the airend and
back to the inlet valve via the venting valve.
The compressor motor runs without load and draws little current.
■ STANDSTILL:
The inlet valve is closed. The minimum pressure/check valve shuts off the oil separator from the
distribution network. The oil separator tank is vented.
The drive motor is stopped.
■ PROPORTIONAL:
With the help of a control valve (proportional controller), the degree of opening of the inlet valve
is continuously varied in relation to the actual 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.
4.7.2 Control modes
Using the selected control mode, the controller switches the compressor between its various opera‐
tional states in order to compensate for air being drawn of by consumers and maintain system pres‐
sure between the set minimum and maximum values.
The SIGMA CONTROL BASIC can work with the following control modes:
■ DUAL
■ QUADRO
■ MODULATING control
The SIGMA CONTROL BASIC is factory set to QUADRO control mode unless specifically ordered
otherwise.
DUAL
In the DUAL control mode, the machine is switched back and forth between LOAD and IDLE to
maintain pressure between the preset minimum and maximum values. When maximum pressure is
reached, the machine switches to IDLE. When the preset
idle period has elapsed, the machine
switches to STANDSTILL.
The
idling time is fixed in SIGMA CONTROL BASIC.
4
Design and Function
4.7
Operating modes and control modes
Number: 9_6945 01USE
Service manual Screw compressor
Aircenter SX 3/7.5 SIGMA CONTROL BASIC
25
Option C1
Option C1
