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NI 9503 User Manual and Specifications
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© National Instruments
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31
Measurement Category I is for measurements performed on
circuits not directly connected to the electrical distribution system
referred to as
MAINS
voltage. MAINS is a hazardous live electrical
supply system that powers equipment. This category is for
measurements of voltages from specially protected secondary
circuits. Such voltage measurements include signal levels, special
equipment, limited-energy parts of equipment, circuits powered by
regulated low-voltage sources, and electronics.
Caution
Do
not
connect the NI 9503 to signals or use
for measurements within Measurement Categories II, III,
or IV.
Note
Measurement Categories CAT I and CAT O
(Other) are equivalent. These test and measurement
circuits are not intended for direct connection to the
MAINs building installations of Measurement
Categories CAT II, CAT III, and CAT IV.