Kikusui TOS9301 - Grounding Mode (GND)

TOS93 Series User’s Manual 71
Withstanding Voltage and Insulation Resistance Tests | Setting Test Conditions
Grounding mode (GND)
Select whether to include the current running through the stray capacitance (p.321) of test leads, tools,
and the like in measurements. An i
con is shown in the upper right of the display according to the setting.
 When set to Low (example of ACW)
Value Description Icon
Low Measures by including the current running through the stray capacitance across test leads or
tools and ground and the current running through the insulation resistance. Tests can be
performed safely without the risk of shorting the ammeter.
Guard High-sensitivity high-precision measurement is possible because the current running through the
stray capacitance across test leads or tools and ground and the current running through the
insulation resistance are excluded from measurement. Use this mode only when the EUT and
tools and the like are completely floating. If one end of the EUT is grounded to earth or if the LOW
te
rminal and chassis a
re shorted, the ammeter will be shorted. This is extremely dangerous.
WARNING
• If there is a possibility that the EUT or tools and the like will be grounded or if you
are uncertain about it, do not set GND to Guard. Doing so is extremely dangerous
because the ammeter will be shorted and will not be able to measure current.
• If you set GND to Guard, do not connect measuring instruments that are grounded
at one end (e.g., Kikusui 149-10A High Voltage Digital Voltmeter, TOS120
0 Current
Calibrator) to this product. Doing so is extremely dangerous because the ammeter
will be shorted and will not be able to measure current.
Using the product in a high humidity environment when GND is set to low will adversely
affect the measurement accuracy in insulation resistance tests. If the grounding mode (GND)
is set to low in a high humidity environment, the current will leak to the ground from the high-
voltage wiring sections inside the product and the high-voltage wiring sections between the
product and the EUT. This leakage current ranges from several nA to several tens of μA
depending on the usage and wirin
g conditions of the optional TOS932
0 high voltage
scanner. The effects of leakage current can be reduced by making measurements with the
offset enabled.
A
Stray capacitance and
insulation resistance of
test leads, tools, etc.
Set to Low
Ammeter
TOS93
HIGH
LOW
A
Stray capacitance and
insulation resistance of
test leads, tools, etc.
Set to Low
Ammeter
TOS93
HIGH
LOW
Can be used with a grounded EUT
Can be used with a ungrounded EUT
EUT
EUT