1-9
1.9.3 Coulombs verification
Coulombs verification is performed by applying accurately
known charge values derived from a voltage source and a
capacitor to the Model 6517A INPUT jack, and then verify-
ing that Model 6517A readings fall within specified limits.
Follow the steps below to verify coulombs measurement ac-
curacy.
1. Connect the Model 6517A to the calibration standard
then to the voltage calibrator, as shown in Figure 1-4.
Initially, make the connections to the 1nF capacitor.
2. Turn on the Model 6517A and the DC voltage calibrator,
and allow a one-hour warm-up period before making
measurements.
3. Restore Model 6517A factory default conditions, as
explained in paragraph 1.7. Also make sure that the off-
set-nulling procedure discussed in paragraph 1.8 has
been performed.
Table 1-7
Limits for 20µA–20mA range verification
6517A
range
Applied DC
current
Reading limits
(1 year, 18° to 28°C)
20µA
200µA
2mA
20mA
19.0000µA
190.000µA
1.90000mA
19.0000mA
18.9805µA to 19.0195µA
189.805µA to 190.195µA
1.89800mA to 1.90200mA
18.9805mA to 19.0195mA
1. Repeat procedure for negative currents.
2. Reading limits shown calculated only from Model 6517A one-year
accuracy specifications and do not include test equipment
uncertainty.
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
INPUT
250V PEAK
!
LINE RATING
50-60HZ
50VA MAX
AC ONLY
LINE FUSE
SLOWBLOW
1/2A 90-125V
1/4A 180-250V
IEEE-488
(CHANGE IEEE ADDRESS
WITH FRONT PANEL MENU)
DIGITAL
I/O
TRIG LINK
115V
LO
HI
RS232
!
MADE
IN
U.S.A.
PREAMP OUT
250 PEAK
COMMON
2V ANALOG
OUTPUT
TEMP
TYPE K
HUMIDITY
OPTION SLOT
V SOURCE
EXT TRIG
IN
MTR COMP
OUT
INTERLOCK
SELECTED
LINE VOLTAGE
90-110V
105-125V
180-220V
210-250V
1010V
PEAK
750V
PEAK
Low-noise Coax BNC Cable
Triax-to-BNC Adapter
Model 6517 Electrometer
BNC-to-dual
Banana Plug
Adapter (Connect
Cable Shield to
Output LO)
DC Current Calibrator
Figure 1-3
Connections for 20µA–20mA range verification
4. Select the coulombs function and the 2nC range on the
Model 6517A.
5. Compute the desired calibrator voltages as follows:
Where: V = calibrator voltage in volts
Q = charge in coulombs
C = standard capacitance value in farads
After calculating the voltage values, enter them where
indicated in Table 1-8.
6. With zero check enabled, press REL to zero correct the
instrument.
7. Disable zero check, and set the voltage calibrator output
to 0.0000V.
8. Set the calibrator output to the calculated voltage. Allow
the reading to settle completely.
9. Compare the Model 6517A displayed reading with the
limits shown in Table 1-8.
10. Set the calibrator output to 0.000000V, and enable zero
check.
11. Repeat steps 5 through 10 for the remaining ranges
listed in Table 1-8. For each range, be sure to:
• Set the Model 6517A to the appropriate range.
• Make connections to the correct capacitor in the cali-
bration standard.
• Set the calibrator to 0V with zero check disabled.
• Set the voltage calibrator to the calculated voltage
value.
• Compare the Model 6517A reading with the stated
reading limits.
V
Q
C
----
=