376 Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide
24 Reference
 
Measurement Category Definitions
The "Not rated for CAT II, III, IV" measurement category is for measurements 
performed on circuits not directly connected to MAINS. Examples are 
measurements on circuits not derived from MAINS, and specially protected 
(internal) MAINS derived circuits. In the latter case, transient stresses are variable; 
for that reason, the transient withstand capability of the equipment is made known 
to the user.
Measurement category II is for measurements performed on circuits directly 
connected to the low voltage installation. Examples are measurements on 
household appliances, portable tools and similar equipment.
Measurement category III is for measurements performed in the building 
installation. Examples are measurements on distribution boards, circuit-breakers, 
wiring, including cables, bus-bars, junction boxes, switches, socket-outlets in the 
fixed installation, and equipment for industrial use and some other equipment, for 
example, stationary motors with permanent connection to the fixed installation.
Measurement category IV is for measurements performed at the source of the 
low-voltage installation. Examples are electricity meters and measurements on 
primary overcurrent protection devices and ripple control units.
Maximum Input Voltages
Use this instrument only for measurements within its specified measurement category 
(not rated for CAT II, III, IV). No transient overvoltages allowed.
 Maximum input voltage at analog inputs
135 Vrms
50
Ω input: 5 Vrms Input protection is enabled in 50 Ω mode and the 50 Ω load will 
disconnect if greater than 5 Vrms is detected. However the inputs could still be damaged, 
depending on the time constant of the signal. The 50
Ω input protection only functions 
when the oscilloscope is powered on.