DH Instruments PG7000, Руководство по эксплуатации и обслуживанию

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3. GENERAL OPERATION
Page 75 © 1998-2008 DH Instruments, a Fluke Company
The AMBIENT screen is a run screen. This means that other functions can be accessed from
the AMBIENT screen and the active AMBIENT screen will be returned to when leaving functions. The
MAIN screen and SYSTEM screens are also
run screens (see Sections 3.7 and 3.9.5).
The AMBIENT run screen displays:
1. <nnnnnnn uuuu>: Current numerical value and pressure
unit of atmospheric pressure. Source of value can be internal
measurement, remote barometer, default or user depending
on current SETUP selection (see Section 3.10). The unit of
measure is determined by the UNIT function setting (see
Section 3.9.3). ATM head is applied to internal or external
barometer reading to correct atmospheric pressure to the
PG7000 reference level (see Section 3.11.3.3). Indicates
< --
-- > when information is unavailable or out of range.
Indicates <TIMEOUT> if the current SETUP selection is a
remote barometer and PG7000 communication with the
barometer times out.
nnnnnnn uuuu nn.n°C
nn%RH n.nnnnnn/s2
2. <n.nn°C>: Current ambient temperature. Source of value can be internal measurement, default or user
depending on current SETUP selection (see Section 3.10). The unit of measure is degrees Centigrade [ºC]
and cannot be changed. Indicates < ---- > when information is unavailable or out of range.
3. <n.nnnnnnm/s2>: Value of local acceleration due to gravity. Can be default or user depending on current SETUP
selection (see Section 3.10). The unit of measure is meters per second squared (m/s2) and cannot be changed.
4. <nn%RH>: Current ambient relative humidity. Can be internal measurement, default or user depending on
current SETUP selection (see Section 3.10). The unit of measure is percent relative humidity (%RH) and
cannot be changed. Indicates
< -- > if current SETUP selection is internal and current measurement is
unavailable or out of range.
Pressing [ESCAPE] in the AMBIENT run screen returns operation to the MAIN run screen.
All function keys are active from the AMBIENT run screen and operation returns to that
screen when leaving functions that were accessed from it.
The current selection in SETUP determines the source of the values used by PG7000 for
atmospheric pressure, ambient temperature and relative humidity. If the SETUP setting for these
values is user or default, the AMBIENT screen displays the user or default value, not PG7000’s
on-board measurement(s).
To change the ambient pressure units of measure, see Section 3.9.3. When the current
pressure unit of measure is an altitude unit, atmospheric pressure in the AMBIENT run screen is
expressed in kPa if the altitude unit is meters (m) or psi if the altitude unit is feet (ft).
3.9.7 [HEAD]
PURPOSE
To cause a pressure value, representing the fluid head resulting from a difference in height,
to be added to the pressure defined by PG7000 at its reference level. To set the height of
the DUT head.
PRINCIPLE
The pressure defined by the PG7000’s floating piston is the pressure at the bottom of the piston.
This is referred to as the PG7000 reference level. The height of the bottom of the piston with
the piston in mid-stroke position is marked
reference level on the PG7000 piston-cylinder
module mounting post. Frequently, when performing a calibration or test, the device or
system under test is at a different height than the PG7000 reference level. This difference in
height (referred to as
DUT head ) can cause a significant difference between the pressure
defined by the PG7000 at its reference level and the pressure actually applied to the device
under test located at a different height. In this case, it is useful to make a head correction to