Ingersoll-Rand EP 20 SE, Варианты руководства оператора/инструкции по эксплуатации, Страница: 27 / 70

25
Modulation/ACS Control (Optional)
For those plants which have relatively high constant
air demand, relative to the compressor capacity, the
recommended control mode is modulation.
The modulation control system retains the features
of the on line-off line control, but provides for
throttling of the inlet flow up to the off line air
pressure set point value.
By applying line pressure to an adjustable modulator
valve, the throttling position of the inlet valve is
controlled, thus allowing the modulator to "trim" the
inlet valve position as dictated by the line pressure.
The modulating pressure range is about 4 psig (0.3
BAR) and the modulator is factory set to straddle the
compressor rated pressure. Modulation begins when
the line pressure reaches about 99 percent of the
compressor rated pressure and continues as/if the
line pressure rises. Modulation becomes stable
when the compressor output equals the plant air
demand. When the modulation is at the factory
setting, the maximum capacity reduction will be
approximately 60 percent of the compressor rated
capacity (as indicated in Figure 4.7-1).
If the air demand has decreased to a level below the
60 percent modulated output, the line pressure will
increase slightly to actuate the Intellisys. The
compressor will then shift to the off line control
position, and operate unload with the compressor
vented.
It is sometimes desirable to begin modulation at a
higher pressure than the standard factory setting,
thereby increasing the modulated capacity at the
time the Intellisys is actuated. Refer to Figure 4.7-1
for modulated capacities available when this is done.
FIGURE 4.7-1