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NI 9229/9239
26
ni.com
Meas
u
rement Category I is for meas
u
rements performed on
circ
u
its not directly connected to the electrical distrib
u
tion system
referred to as MAINS voltage. MAINS is a hazardo
u
s live
electrical s
u
pply system that powers eq
u
ipment. This category is
for meas
u
rements of voltages from specially protected secondary
circ
u
its. S
u
ch voltage meas
u
rements incl
u
de signal levels, special
eq
u
ipment, limited-energy parts of eq
u
ipment, circ
u
its powered by
reg
u
lated low-voltage so
u
rces, and electronics.
Caution
Do
not
connect to signals or
u
se for
meas
u
rements within Meas
u
rement Categories II,
III, or IV.
Meas
u
rement Category II is for meas
u
rements performed on
circ
u
its directly connected to the electrical distrib
u
tion system.
This category refers to local-level electrical distrib
u
tion, s
u
ch as
that provided by a standard wall o
u
tlet, for example, 115 V for U.S.
or 230 V for E
u
rope.
Caution
Do
not
connect to signals or
u
se for
meas
u
rements within Meas
u
rement Categories III or IV.