BASIC OPERATION
64
Cable guard
: Used in the case where the impedance
of the circuit under test is greater than 1GΩ, using
the high-impedance guard connection. It is usually
necessary to use shielded wires and test fixtures to
test high-impedance equipment, which can reduce
interference and protect the users from being injured
by hazardous voltage on the guard shield (or plate).
The CABLE guard selection provides a high-
impedance (~10kΩ) driven guard to prevent positive
feedback, which could cause oscillations when using
shielded cables. Cable guard is used to drive the
shields of cables and test fixtures. Inside the test
fixture, the guard can be connected to a guard plate
or shield that surrounds the DUT.
WARNING: To prevent electric shock injury, a
safety shield must be used to prevent physical
contact with a guard plate or guard shield that is at
a hazardous potential (above 30Vrms or higher
than 42.4Vpeak). The guard plate or guard shield
must completely be enclosed by the safety shield
device which must be connected to the earth
ground.
In the fixed device, a triaxial cable can be used to
connect the GSM and the device under test. The wire
in the center is connected to the Input/Output HI
terminal, the metal plate is connected to the V.Ω
GUARD terminal, and the safety shield is connected
to the Input/Output LO (connected to the earth
ground).
Coaxial cables can be used when the potential of the
V.Ω GUARD terminal is not higher than 30Vrms
(42.4V peak), the center wire is connected to the
InputT/Output HI terminal of the GSM, and the
metal plate is connected to the V.Ω GUARD
terminal.
Figure below shows the cable guard connection
Содержание GSM-20H10
Страница 107: ...GSM 20H10 User Manual 105 The operating flow of Grading mode is shown in the figure below ...
Страница 108: ...BASIC OPERATION 106 ...
Страница 110: ...BASIC OPERATION 108 ...
Страница 166: ...SYSTEM SETTINGS 164 ...
Страница 244: ...COMMAND SYNTAX 242 Example ROUTe TERMinals ...