Fluke 5790B, Руководство по обслуживанию

Страница: 60 / 172

5790B
Service Manual
3-22
2. Set up the 5730A as follows so that its internal ac transfers are off:
a. Push the “Setup Menus” softkey.
b. Push the “Special Functns” softkey.
c. Push the “ACXfer Choice” softkey so that ON appears.
d. Push PREV MENU twice.
e. Set the 5730A to 1 V, 1 kHz, operate. Push the “Intrnl Xfers”
softkey so that OFF appears. (The “Intrnl Xfers” softkey appears
only in the 5730A ranges below 220 V and at frequencies below
120 kHz.)
f. Push 0,V, 0, Hz, ENTER, on the 5730A. Leave the 5730A in
standby.
3. Select INPUT 1 so that its indicator ring is lit up, and then select Setup
Menu>Calibration>Adjust AC All Main . The display changes to indicate
the first AC Step: LF (10 Hz) Linearity.
4. For all the ac cal points down to the 70 mV range, use the Fluke
Calibration 792A AC/DC Transfer Standard to adjust the ac voltage level
being applied to the 5790B INPUT1 connector. There are three
procedures for ac calibration points, depending on their amplitude. Go to
the appropriate step as defined below:
•
Step 6: 2 V through 600 V
•
Step 7: 60 mV through 600 mV
•
Step 8: 2 mV through 20 mV
5. For an ac calibration point in the 2 V through 1000 V range, proceed as
follows:
a. Obtain a copy of Figure 3-6, the worksheet for this group. Fill in
the test voltage and frequency and the associated 792A
correction.
b. If the test voltage is above 220 V, add the 792A 1000 V range
resistor to the test setup as shown in Figure 3-8.
c. Push the “Continue” softkey. This automatically selects the correct
Product range.
d. 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 the 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.
e. Set the 5730A to the nominal test voltage, dc positive (Do not use
a characterized setting as the Product is now used as the dc
reference, thus allowing for any resistive drop caused by the 792A
loading). Wait for the 5730A “U” annunciator to go out.
f. Wait for 30 seconds for the DMM reading to stabilize. Record the
DMM reading under the 792A column in the worksheet for +DC.