Keysight U1251B Operating and maintenance instructions

Keysight U1251B and
U1252B Handheld
Digital Multimeter
Quick Start
Guide

Contacting Keysight
www.keysight.com/find/assist
(worldwide contact information for
repair and service)
Safety and EMC Information
This meter is safety-certified in
compliance with EN/IEC
61010-1:2001, UL 61010-1 Second
Edition and CAN/CSA 22.2
61010-1 Second Edition, CAT III
1000 V/CAT IV 600 V Overvoltage
Protection, Pollution Degree II. Use
with standard or compatible test
probes.
Safety Notices
CAUTION
A CAUTION notice denotes a
hazard. It calls attention to an
operating procedure, practice, or
the like that, if not correctly
performed or adhered to, could
result in damage to the product or
loss of important data. Do not
proceed beyond a CAUTION notice
until the indicated conditions are
fully understood and met.
WARNING
A WARNING notice denotes a
hazard. It calls attention to an
operating procedure, practice, or
the like that, if not correctly
performed or adhered to, could
result in personal injury or
death. Do not proceed beyond a
WARNING notice until the
indicated conditions are fully
understood and met.
Safety symbols
Earth (ground) terminal
Equipment protected
throughout by double
insulation or reinforced
insulation
Caution, risk of electric
shock
Caution, risk of danger
(refer to the instrument
manual for specific Warning
or Caution information)
CAT III
1000 V
Category III 1000 V
overvoltage protection
CAT IV
600 V
Category IV 600 V
overvoltage protection
2 Keysight U1251B and U1252B Quick Start Guide
For further safety information details, refer to the
Keysight U1251B and U1252B Handheld Digital Multimeter User’s Guide.
ENGLISH

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The following items are included with your
multimeter:
✔Silicone test leads
✔4 mm probes
✔Alligator clips
✔Printed Quick Start Guide
✔Certificate of Calibration
✔9 V alkaline battery (for U1251B only)
✔Rechargeable 8.4 V battery (for U1252B only)
✔Power cord and AC adapter (for U1252B only)
If anything is missing or damaged, please contact
the nearest Keysight Sales Office.
NOTE
Your multimeter is capable of remote data logging.
To use this feature, you will need an IR-USB cable
(U1173A, purchased separately) and the Keysight
GUI Data Logger Software (downloadable from
www.keysight.com/find/hhTechLib).
WARNING
Ensure the terminal connections are correct for that
particular measurement selection before starting any
measurement. To avoid damage to the device, do not
exceed the input limit.

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Charging the Battery
Use the specified accessory, the 24 V DC adaptor
to charge the battery.
1Remove and disconnect the test leads from
the meter.
2Turn the rotary switch to the position.
Connect the power cord to the DC adapter.
3Plug the Red (+)/ Black (–) banana terminals
of the DC adapter to the and the COM
terminals respectively. The DC adaptor can be
replaced with a DC power supply in order to
set the 24 V DC output and the over current
limitation to a value more than 0.5 A. Ensure
that the polarity of the connection is correct.

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4The primary display indicates “bAt” and the
“SbY” flashes on the secondary display and a
short tone sounds to remind you whether to
charge the battery or not. Press to start
charging the battery, or the meter will
automatically start the self-test after the 24 V
supply is applied. We recommend not to
charge the battery if its capacity is over 90%.
NOTE
For the battery charger, the mains supply voltage
should not fluctuate by plus or minus 10%.
CAUTION
– Do not rotate the rotary switch from
position when charging the battery.
– Perform battery charging only with 7.2 V or
8.4 V NiMH rechargeable battery, 9 V size.
– Disconnect test leads from all the terminals
when charging the battery.
– Ensure proper insertion of battery in the
multimeter, and follow the correct polarity.
– Upon initial use (or after a prolonged storage
period), the rechargeable battery may require
three to four charge/discharge cycles before
achieving maximum capacity. To discharge,
simply run the multimeter under the
rechargeable battery's power until it shuts
down or the low battery warning appears.
– The multimeter may indicate that charging is
complete after ten minutes when charging a
new rechargeable battery. This is a normal
phenomenon with rechargeable batteries.
Remove the rechargeable battery from the
device, reinsert it, and repeat the charging
procedure.

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Functions and Features
Action Steps
Turns ON backlight Press .
Checks battery capacity Press and hold for >1 s.
Freezes the measured value Press .
Starts MIN/MAX/AVG recording Press and hold for >1 s.
Offsets the measured value Press .
Changes the measuring range Press .
Turns on auto range Press and hold for > 1 s.
Turns on dual display Press .
Starts manual data logging Press and hold for > 1 s.
Views the logged data Press for > 1 s, press to
scroll through the logged data.
Clears the logged data Press for > 1 s, press
for >1 s.

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Input Terminals and Overload Protection
Measurement Functions Input Terminal Overload Protection
Voltage COM 1000 V R.M.S
Diode 1000 V R.M.S
< 0.3 A short circuit
current
Resistance
Capacitance
Temperature
Current (μA and mA) µA.mA COM 440 mA/1000 V
30 kA/fast-acting fuse
Current (A) A COM 11 A/1000 V
30 kA/fast-acting fuse

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Performing Voltage Measurements
Measuring AC voltage
1Set the rotary switch to . For and
mode, press to ensure is
shown on the display.
2Connect the red and black test leads to input
terminals V. mV (red) and COM (black)
respectively.
3Probe the test points and read the display.
4Press to display dual measurements.
Parameter can be switched consecutively.

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Measuring DC voltage
1Set the rotary switch to or . Ensure
that is shown on the display.
2Connect the red and black test leads to input
terminals V. mV (red) and COM (black)
respectively.
3Probe the test points and read the display.
4Press to display dual measurements.
Parameters can be switched consecutively.
Using the Filter
1To enter the Setup mode, switch off the
meter, then turn the rotary knob to any
non-OFF position while holding until
you hear a beep. You may release once
you hear the beep.
2Press or to scroll through the menu items
until FiLtE is shown in the secondary display.
3Press or to enable the Filter.
4Press to save your changes.
5Press and hold until the meter restarts
and returns to its normal operating mode.
NOTE
For measuring DC voltage from a mixed signal in DC
measurement mode, ensure that the Filter is enabled.
CAUTION
To avoid possible electric shock or personal injury,
enable the Filter to verify the presence of hazardous
DC voltages. Displayed DC voltages can be
influenced by high frequency AC components and
must be filtered to assure an accurate reading.

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Performing Current Measurements
To perform current measurements, set up your
multimeter as shown in the figure below. For
measuring DC current from a mixed signal in DC
measurement mode, ensure that the Filter is
enabled.
Measuring AC current
1Set the rotary switch to or .
Press to ensure is shown on the
display.
2Connect the red and black test leads to input
terminals µA.mA (red) and COM (black) or
A (blue) and COM (black) respectively.
3Probe the test points in series with the circuit
and read the display.