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WARNING
CAUTION
5-16
■ GUARD
• If it is not known whether the DUT or jig is grounded, never select GUARD.
If GUARD is selected while the DUT is grounded, the ammeter will be
short-circuited, thereby disabling measurement and posing a grave dan-
ger. See Fig. 5-4 (B).
• If GUARD is selected, do not connect this tester to any measuring instru-
ments or other devices that involve single-side grounding, such as Kiku-
sui's high-voltage digital voltmeter 149-10A and current calibrator
TOS1200. Otherwise, the ammeter will be short-circuited. See Fig. 5-4 (A).
HIGH VOLTAGE terminal
Ammeter
TOS9213S
TOS9213AS
(A) Connecting the 149-10A
HIGH VOLTAGE terminal
Ammeter
TOS9213S
TOS9213AS
(B) Selecting GUARD when the DUT is grounded
Fig.5-4 Dangerous connection
• If the LOW terminal of this tester is connected to the HIGH or LOW termi-
nal of the earth continuity tester TOS6200, the ammeter will make mea-
surement errors if GUARD is selected, as the resistor inside the TOS6200
is connected in parallel to the tester's ammeter. Therefore, to use the
TOS6200, avoid connecting these terminals, or select LOW.
D
U
T
LOW
terminal
Setting to GUARD
D
U
T
LOW
terminal
Setting to GUARD
149-10A
Insulation
resistance of
the test lead
wire and jigs
TOS9213S/ TOS9213AS
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