QUADRO
In the QUADRO mode, the controller operates as in the DUAL mode during periods of high air demand
by switching between LOAD and IDLE, but during periods of low air demand it switches directly to
STANDSTILL.
This mode of control requires two preset time periods: the
running period and the idle/standstill pe‐
riod.
The
idling/stopped and the running time are set in SIGMA CONTROL BASIC.
MODULATING control
MODULATING control is based on the DUAL control mode. The difference to DUAL is that the gas
delivery is continuously varied within the control range of the machine.
This control mode is not available on variable speed machines with a frequency-controlled
drive (SFC).
Compressed air demand
Operating states
Rises
MODULATING
LOAD
Falls
MODULATING
IDLE
STANDSTILL
Tab. 22 Operating states under MODULATING control
4.8 Refrigeration Dryer Control Modes
The controller can operate in the following modes:
■ CONTINUOUS
■ TIMER
CONTINUOUS
In this mode the refrigeration dryer runs continuously, even if the compressor is shut down.
This mode of control is set up at the factory.
TIMER
The refrigeration dryer is time-controlled and is switched on and off when the compressor is stopped.
In this mode, the operating temperature is held within tight limits.
This control mode saves energy.
Which control mode is the most practical, and when?
Control mode Advantage
Disadvantage
CONTINUOUS Constant dew point.
Higher power consumption when the compres‐
sor is shut down
4
Design and Function
4.8
Refrigeration Dryer Control Modes
26
Service manual Screw compressor
Aircenter SX 3/7.5 SIGMA CONTROL BASIC
Number: 9_6945 01USE
Option C1
