Ground Relay Contact Resistance Tests - Keithley 6521 Instruction Manual

4.3.6 Ground relay contact resistance tests

Perform the following steps to verify that the contact resis-
tance of the ground relay for each channel is within specifie
limits.
1. Connect an alligator clip lead to the HI and LO input
jacks of the DMM to be used for the test. (See Figure
4-3.)
2. Turn on the DMM, and allow it to warm up for one hour
before making the tests.
3. Select the ohms function and the 20Ω range on the
DMM.
4. Temporarily short the ends of the DMM leads together,
then enable the DMM REL mode to null out any resid-
ual test lead resistance. Leave REL enabled for the re-
mainder of the contact resistance tests.
EDIT ERR REM TALK LSTN SRQ REAR REL FILT MATH 4W AUTO ARM TRIG
1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8
2001 MULTIMETER
PREV DCV ACV DCI ACI Ω2 Ω4 FREQ TEMP
DISPLAY
NEXT
REL TRIG STORE RECALL FILTER MATH
POWER
INFO LOCAL CHAN SCAN CONFIG MENU EXIT ENTER
Model 2001 DMM
Figure 4-3
Connections for ground relay contact resistance tests
Input HI
SENSE
INPUT
Ω 4 WIRE
HI
SMPL
9 10
350V 1100V
!
PEAK PEAK
LO
500V
PEAK
INPUTS
RANGE F R
Input LO
AUTO
FRONT/REAR
2A 250V
AMPS
RANGE
CAL
5. With the power off, install the scanner card in the Model
6517 Electrometer OPTION SLOT.
6. Turn on the Model 6517 power.
7. Press CONFIG then CARD, and program the Model
6517 for the current scan mode. (See paragraph 3.4.4 for
details.)
8. Press the OPTION CARD button, then select OPEN-
ALL-CHANNELS in the CHANNEL SELECTION
menu to make certain that all channels are open.
9. Connect the DMM to the HI and LO terminals of the
channel 1 input jack, as shown in Figure 4-3.
10. Note the resistance reading on the DMM. Verify that the
reading is <1Ω.
11. Repeat steps 9 and 10 for channels 2-10. Be sure to con-
nect the DMM to the HI and LO input terminals of the
channel being tested. Also, the channel being tested
must be open so that the ground relay is closed.
H H
L
Out
L
G
H
L
Model 6521/22 Card
Service Information
IN 1
IN 10
Note: Model 6521 shown. Model
6522 connections same except
for triax inputs.
Channel 1 connection shown
4-5