Fluke 5790B, Руководство по обслуживанию

Страница: 61 / 172

Calibration Adjustment and Verification
Calibration
3
3-23
Record the reading on the Product Output Display under the
5790B column for +DC.
g. Push [
±
][ENTER] on the 5730A to toggle output polarity.
h. Again, allow the DMM reading to stabilize. Record the DMM
reading under the 792A column in the worksheet for -DC. Record
the reading on the Product Output Display under the 5790B
column for -DC. Ignore polarity for the Product reading (record the
absolute value).
i. Apply the frequency required for the calibration step. Wait for the
“U” annunciator on the 5730A to go out.
j. Allow the DMM reading to stabilize. Record the DMM reading
under the 792A column in the worksheet for ac. Do not record a
reading for the Product.
k. Now do a computation to get the measured ac using the formulas
shown in the worksheet:
1) Compute the average of the dc readings for the Product
and the 792A as shown.
2) Compute “AC MEAS” using the formula shown. Be sure to
include the 792A correction as indicated in the formula.
l. Observe the default “EXACT VALUE” on the display. It shows the
allowed number of decimal places for you to enter. Enter your
computation of “AC MEAS” in the Product using the keypad, and
push the [ENTER] key. After you push [ENTER], the Control
Display shows the progress of the internal process of the
calibration step.
Note
While a calibration step is in progress, inaccurate values may appear
on the Measurement Display. This is normal. When the Product is
finished with the step, the display will read accurately.
m. When the step has completed, set the 5730A to standby.
6. For an ac calibration point in the 60 mV through 600 mV group, you will
need to adjust the 5730A in accordance with the error displays that you
recorded in Table 3-2. Proceed as follows:
a. Obtain a copy of Figure 3-7, the worksheet for this group. Fill in
the voltage, frequency, 5730A error displays (positive and
negative) from Table 3-2, and the associated 792A correction.
b. Push the “Continue” softkey. This automatically selects the
appropriate 5790B range.
c. Set the 792A INPUT RANGE knob to the appropriate position.
Always use the lowest range that will accept the input.

Caution
Always ensure that the proper range has been selected before
applying voltage to the 792A input. Inputs that exceed the
protection level shown on its rear panel label disrupt the state
of calibration and can cause instrument damage.