Input Terminal Protection Limits; Sense Terminal Protection Limits; Iec Measurement Category Ii Overvoltage Protection - DATATEC EDU34450A Guia Del Usuario

Input Terminal Protection Limits

Protection Limits are defined for the input terminals:
Main Input (HI and LO) Terminals. The HI and LO input terminals are used for voltage, resistance, capacitance, and
diode test measurements. Two Protection Limits are defined for these terminals:
– HI to LO Protection Limit. The Protection Limit from HI to LO ("A" in the figure above) is 1000 VDC or 750 VAC,
which is also the maximum voltage measurement. This limit can also be expressed as 1000 Vpk maximum.
– LO to Ground Protection Limit. The LO input terminal can safely "float" a maximum of 500 Vpk relative to ground.
This is Protection Limit "B" in the figure above.
Although not shown on the figure, the Protection Limit for the HI terminal is a maximum of 1000 Vpk relative to the
ground. Therefore, the sum of the "float" voltage and the measured voltage must not exceed 1000 Vpk.
Current Input Terminal. The current input ("I") terminal has a Protection Limit of 3 A (rms) maximum current flowing
from the LO input terminal. This is Protection Limit "C" in the figure above. Note that the current input terminal will
be at approximately the same voltage as the LO terminal.
The current-protection circuitry includes a fuse on the front panel. To maintain protection, replace this fuse only
with a fuse of the specified type and rating.

Sense Terminal Protection Limits

The HI and LO sense terminals are used only for four-wire resistance measurements ("Ω 4W"). The Protection Limit is
200 Vpk for all of the terminal pairings ("D" in the figure above):
– LO sense to LO input.
– HI sense to LO input.
– HI sense to LO sense.
The 200 Vpk limit on the sense terminals is the Protection Limit. Operational voltages in resistance measurements
are much lower - less than 5 V in normal operation.

IEC Measurement Category II Overvoltage Protection

To protect against the danger of electric shock, the Keysight EDU34450A 5½ Digit Multimeter provides overvoltage
protection for line-voltage mains connections meeting both of the following conditions:
– The HI and LO input terminals are connected to the mains under Measurement Category II conditions, defined
below, and
– The mains are limited to a maximum line voltage of 300 VAC rms.
IEC Measurement Category II includes electrical devices connected to mains at an outlet on a branch circuit. Such
devices include most small appliances, test equipment, and other devices that plug into a branch outlet or socket.
The EDU34450A may be used to make measurements with the HI and LO inputs connected to mains in such devices,
or to the branch outlet itself (up to 300 VAC rms). However, the EDU34450A may not be used with its HI and LO
12 Keysight EDU34450A User's Guide