4 34410A/11A/L4411A User’s Guide
Protection Limits
The Keysight 34410A/11A and L4411A Digital
Multimeters provide protection circuitry to pre-
vent damage to the instrument and to protect
against the danger of electric shock, provided
the Protection Limits are not exceeded. To
ensure safe operation of the instrument, do not
exceed the Protection Limits shown on the
front and rear panel, and defined below:
Note: The front-panel terminals are shown
above. The rear-panel terminals are identical.
The Front/Rear switch selects the terminal set
to be used. Do not operate this switch while
signals are present on the front or rear termi-
nals. The current-protection fuse is on the rear
panel.
Input Terminal Protection Limits
Protection Limits are defined for the input ter-
minals:
Main Input (HI and LO) Terminals. The HI
and LO input terminals are used for voltage,
resistance, capacitance, and diode test mea-
surements. Two Protection Limits are defined
for these terminals:
HI to LO Protection Limit. The Protection
Limit from HI to LO ("A" in the figure at left) is
1000 VDC or 750 VAC, which is also the
maximum voltage measurement. This limit
can also be expressed as 1000 Vpk maxi-
mum.
LO to Ground Protection Limit. The LO
input terminal can safely "float" a maximum
of 500 Vpk relative to ground. This is Protec-
tion Limit "B" in the figure.
As is implied by the above limits, the Protection
Limit for the HI input terminal is a maximum of
1500 Vpk relative to ground.
Current Input Terminal. The current input ("I")
terminal has a Protection Limit of 3A (rms)
maximum current flowing from the LO input ter-
minal. This is Protection Limit "C" in the figure.
Note that the current input terminal will be at
approximately the same voltage as the LO ter-
minal.
Note: The current-protection circuitry includes
a fuse on the rear panel. To maintain protec-
tion, 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 and temperature mea-
surements ("
Ω 4W"). The Protection Limit is
200 Vpk for all of the terminal pairings ("D" in
the figure):
LO sense to LO input.
HI sense to LO input.
HI sense to LO sense.
Note: The 200 Vpk limit on the sense terminals
is the Protection Limit. Operational voltages in
resistance measurements are much lower —
less than 10 V in normal operation.
IEC Measurement Category II
Overvoltage Protection
To protect against the danger of electric
shock, the Keysight 34410A/11A and L4411A
Digital Multimeters provide 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.
IEC Measurement Category II includes electri-
cal 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 34410A/11A and L4411A 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). However,
the 34410A/11A and L4411A may not be used
with its HI and LO inputs connected to mains in
permanently installed electrical devices such
as the main circuit-breaker panel, sub-panel
disconnect boxes, or permanently wired
motors. Such devices and circuits are subject
to overvoltages that may exceed the protection
limits of the 34410A/11A and L4411A.
Note: Voltages above 300 VAC may be mea-
sured only in circuits that are isolated from
mains. However, transient overvoltages are
also present on circuits that are isolated from
mains. The Keysight 34410A/11A and L4411A
are designed to safely withstand occasional
transient overvoltages up to 2500 Vpk. Do not
use this equipment to measure circuits where
transient overvoltages could exceed this level.
To Next Page
Loading...
