Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-15
Model 7700 switching module
Connections for the Model 7700 switching module are shown in Figure 3-5. Note that
only channels 21 and 22 can be used for current measurements.
Figure 3-5
DCI and ACI connections using Model 7700 switching module
Amps measurement procedure
NOTE Make sure the INPUTS switch is in the correct position. To use front panel
inputs, it has to be in the “F” (out) position. For switching modules, it has to be
in the “R” (in) position.
1. If a switching channel is presently closed (displayed), press OPEN to open it.
2. Select the amps measurement function by pressing DCI or ACI.
3. Use the RANGE
Δ and ∇ keys to select a measurement range consistent with the
expected current, or press AUTO to select autoranging (AUTO annunciator turns
on). Details on range are provided in Section 4.
4. Apply the current(s) to be measured.
CAUTION Do not apply more than 3A to the input or the AMPS fuse will blow.
Model 7700 switching module — When performing current measure-
ments, the maximum allowable voltage is 60VDC or 30V RMS.
Exceeding these limits could cause damage to the switching module.
5. If using a switching module, use the and keys to close the desired amps chan-
nel (for the Model 7700, 21, or 22). All other channels will be open.
6. Observe the displayed reading. If the “OVERFLOW” message is displayed, select
a higher range until a normal reading is displayed (or press AUTO for autorang-
ing). For manual ranging, use the lowest possible range for the best resolution.
7. To measure another amps channel, repeat steps 5 and 6.
8. When finished, press OPEN if there is a channel closed.
NOTE When you have an amps-only channel closed, you cannot select a non-amps
function. For example, if channel 21 of the Model 7700 is closed, you cannot
select the DCV function (“INVALID FUNC” displayed).
Model 7700
Switching
Module
H
L
CH 21 or 22
Caution: Maximum input: 60VDC or 30V RMS, 3A switched,
60W, 125VA maximum
Current
Source
2750-900-01.book Page 15 Wednesday, August 3, 2011 7:56 AM
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