User manual

2-6 Connections Model 6485 and 6487 User’s Manual
t^okfkd The maximum safe voltage between picoammeter LO and chassis ground
(common mode voltage) is 42V. The Model 6485 does not internally limit
the LO-to-chassis voltage. Exceeding 42V can create a shock hazard.
If it is possible for the DUT or external supply to present more than 42V to
the input HI, it is imperative that the connection between input LO and the
external voltage source be sufficiently low impedance and capable of car-
rying the short-circuit current of the source, in order that the LO not exceed
42V.
`^rqflk The LO to chassis breakdown voltage is 500V. Exceeding this voltage may
cause damage to the instrument.
Figure 2-6
Shielding for Model 6485 measurements (unguarded)
Model 6487 DUT connections
Current measurement connections
Basic connections for current measurements are shown in Figure 2-7; the DUT is the cur-
rent to be measured. Circuit high is connected to the center conductor of the input connec-
tor and circuit low is connected to the connector’s input LO (inner shield).
HI
LO
DUT
Metal Noise Shield
B. Safety Shield
Metal Safety
Shield
Safety
Earth
Ground
HI
LO
DUT
INPUT
(
220V
Peak)
Metal Noise Shield
A. Noise Shield
INPUT
(
220V
Peak)