GE DigitalFlow DF968, Service Manual

Page: 10 / 78

March 2008
1-2 Calibration
Calibrating the Analog
Outputs
Every Model DF868 flowmeter includes two built-in analog outputs
(A and B) at terminal block
I/O
, which is designated as
Slot 0
. Both the
zero-point and full-scale values for each output must be calibrated.
After calibrating the outputs, which have a resolution of 5.0
μ
A
(0.03% full scale), their linearity should be tested.
Note:
The zero point of the analog output may be set for either 0 mA
or 4 mA. However, the calibration procedure always uses the 4
mA point, as the meter will extrapolate this value to obtain the
0 mA point.
Prepare for the calibration procedure by connecting an ammeter to
analog output A of
Slot 0
, as shown in Figure 1-1 below. Refer to the
menu map in Figure 1-6 on page 1-15.
Figure 1-1: Ammeter Connection (Output A)
Press the
[CAL]
key to enter the Calibration Program :
CALIBRATION ‰ Press
[F1]
to calibrate
Slot 0
. (The
option bar will include a slot
listing for each installed option
card.)
Cal
last slot selected
SLOT0 SLOT1 SLOT2 SLOT3
Terminal Block I/O (Slot 0)
B
RTN
B
SIG
A
RTN
A
SIG
4 1
+ -
Ammeter