6.03
How to Use the Machine
TI008G0001
Modulation (not available for compressors of the AC 6000 series)
All MATTEI compressors are fitted with an automatic system for adjusting pressure according to delivery
pressure. The internal pressure of the compressor depends (partly) on line pressure and, consequently,
on the demand for air; when the latter drops or is nil, line pressure and internal pressure increase. In
Mattei compressors, the maximum pressure at which the unit runs no-load can be set (by calibrating a
valve). For values slightly below maximum, the suction valve is only “partially” closed by suitably modu-
lating machine capacity to line requirements. Maximum pressure and values slightly below this define
a field or range which is known as a MODULATION BAND.
This operating mode exploits this potential. The control unit ignores the Pmax and Pmin. settings and
operates the compressor without stopping except in case of an operator command.
Nota
The modulation bandwidth is typically 0.3 bar.
Suppose maximum no-load pressure is set (using the SERVO-VALVE) to 7.3 bar.
- For pressure values lower than 7 bar (7.3 - 0.3 = 7), the compressor delivers 100% of its capacity.
- For values ranging from 7 to 7.3 bar (the modulation band), the compressor delivers less than its rated
capacity, suitable for line demand.
074
By suitably adjusting the its “servo-valve”, the compressor can modulate before reaching Pmax. This
means that Pmax can only be reached in case of very low or nil demand.
Nota
If the unit is enabled with a line pressure greater than the set minimum pressure, the compressor
does not start but waits for the pressure to fall below the minimum value.
