3. GENERAL OPERATION
Page 83
© 1998-2008 DH Instruments, a Fluke Company
tolerance wider increases the time. However, if the tolerance is set too small so that it
does not correctly reflect the degree of agreement between the pressure controller
pressure measurement and the PG7000’s floating piston, overshoot of the piston float
point or inability to float the piston will result.
The pressure controller tolerance determines, when applicable:
a) the distance from the actual pressure target that pressure is set before the
AutoGen function begins to seek movement of the piston.
b) the amount of pressure overshoot that must occur before “forced rotation” is
used to overcome possible friction between the piston and the cylinder.
This function is used only when the pressure controller is a PPC3.
OPERATION
To view or set the pressure control tolerance, press
[GEN]
,
<5tol>
.
The current value of the pressure control tolerance is displayed. The value is in
% of full scale of the pressure controller. If the pressure controller is
AutoRanged, the AutoRange maximum pressure is used as full scale (see the
pressure controller’s Operation and Maintenance Manual).
The default tolerance value is 0.05% of full scale.
Edit the tolerance value if desired. Do not make the pressure tolerance less than
the worse case agreement between the pressure controller pressure measurement
and the pressure indicated by the PG7000 when its piston is floating.
3.9.9.5
<6REFLOAT>
PURPOSE
To turn ON and OFF a function that causes the automated generation component (see
Section 3.9.9.) to refloat the piston to the target piston position after a new pressure or
mass target is entered, even if the piston is already floating within the piston position
Ready
limits. When Refloat is ON, the piston is always refloated to the target piston
position after a new pressure or mass target command. This gives the full stroke of the
piston to drop before refloat is necessary. When Refloat is OFF, the time required to
activate the pressure control component and refloat the piston is eliminated if it is not
needed. This can result in very rapid pressure setting when the piston is still floating
after a mass load change.
OPERATION
To turn ON and OFF the Refloat function, press
[GEN]
,
<6refloat>
. The cursor is on
the choice corresponding to the current state. Select
<1no>
for the piston NOT to be
controlled to the target position after a pressure or mass command if the piston is
already in the
Ready
piston position limits. Select
<2yes>
for the piston to always to
be controlled to the raise the piston. The default is
<2yes>
.
3.9.9.6
<7VOL>
PURPOSE
To read and/or set the volume of the system to which the PG7000 system is
connected.
This function is used available only with PG7302 and PG7307.
