1-26 Performance Verification Model 2750 Multimeter/Switch System Service Manual
5. Source 1A and 3A, 1kHz full-scale AC currents as summarized in Table 1-13, and
verify that the readings are within stated limits.
6. Press the OPEN key to open Channel 21.
Verifying normal resistance
Check normal resistance by connecting accurate resistance values to the Model 7700 and
verify that its resistance readings are within the specified limits.
CAUTION Do not apply more than 300V between the 7700 plug-in module INPUT or
SENSE H and L terminal, or between any adjacent channels, or instrument
damage could occur.
Follow these steps to verify normal resistance accuracy:
1. Using shielded Teflon or equivalent cables in a 4-wire configuration, connect the
Model 7700 CH1 H and L INPUT terminals, and CH11 H and L SENSE terminals
to the calibrator as shown in Figure 1-13.
2. Install the Model 7700 in Slot 1 of the Model 2750, then turn on the power, and
allow the unit to warm up for two hours before proceeding. Be sure the front panel
INPUTS switch is set to the REAR position.
3. Set the calibrator for 4-wire resistance with external sense on.
4. Select the Model 2750 4-wire resistance function by pressing the 4 key. Close
Channel 1 by pressing the CLOSE key, then ENTER for “SINGLE” channel, and
keying in 101.
5. Set the Model 2750 for the 1 range, and make sure the FILTER is on. Enable
OCOMP (offset-compensated ohms) by pressing SHIFT then OCOMP. (Use
OCOMP for 1, 10, and 100 range verification.)
6. Recalculate reading limits based on actual calibrator resistance values.
Tab le 1- 13
Plug-in module ACI limits
ACV Range Applied AC Voltage Reading Limits @ 1kHz (1 year, 18°C to 28°C)
1A
3A
1.000000A
3.00000A*
0.99860 to 1.00140A
2.9817 to 3.0183A
*If the Fluke 5725A amplifier is not available, apply 2.2A from the calibrator. Reading limits for 2.2A are
2.1949 to 2.2051A.
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