Parker PV046 - Page 9

9
Parker Hannifin Manufacturing Germany GmbH & Co. KG
Pump & Motor Division Europe
Chemnitz, Germany
Electro hydraulic proportional controls version 45 for
axial piston pumps, PV series
Bulletin MSG30-3254-INST/UK
Installation and setup manual
As shown in figure 6, the pressure sensor is
positioned in the pilot circuit. According to the
dierential pressure adjusted at the compensa-
tor valve, the system pressure is higher than the
controlled pressure.
This concept avoids stability problems with the
control loop and the necessity of an external
adjustment of the control loop. On the other
hand there are additional measures necessary
(e.g.: command signal correction), if linearity
between input (command signal) and output
(system pressure) is required.
Figure 7 shows the typical behaviour of pilot
pressure p
p
and system pressure p
1
as function
of the input signal.
The digital control module oers the required
signal correction to compensate for this eect.
The standard module parameter sets already
include this feature for the factory set pressure
dierentialof 15 bar.
For other dierential settings see module oper-
ating instructions.
Figure 7: Pressures vs input signal
p1 = pressure at pump outlet, system pressure
(=p
P
+ ∆p)
∆p = compensator differential
(factory setting 15 bar)
p
P
= pressure at pilot valve, closed loop con-
trolled pressure
command U
P
system press. p
1
, pilot press. p
P