B+K precision 390B Series User manual

Compliance Information
390B, 391B, & 393B
EC Declaration of Conformity - EMC
Compliance was demonstrated to the following specications listed in the Ocial Journal of the European
Communities: EMC Directive 2014/30/EU.
EN 61010 Safety requirements for electrical equipment for measurement, control, and
laboratory use
– Part 1: General requirements
– Part 2-033: Particular requirements for hand-held multimeters and other meters, for
domestic and professional use, capable of measuring mains voltage
EN 61326 Electrical equipment for measurement, control and laboratory use - EMC
requirements
– Part 1: General requirements
– Part 2-1: Particular requirements - Test congurations, operational conditions
and performance criteria for sensitive test and measurement equipment for EMC
unprotected applications
– Part 2-2:Particular requirements - Test congurations, operational conditions and
performance criteria for portable testing, measuring and monitoring equipment used
in low-voltage distribution systems
EN 55011:2009+A1:2010 Industrial, scientic and medical equipment. Radio-frequency
disturbance characteristics. Limits and methods of measurement

Compliance Information 3
IEC 61000 Electromagnetic compatibility (EMC)
– Part 3 – 2: Limits — Limits for harmonic current emissions (equipment input current
≤16 A per phase)
– Part 3-3: Limits - Limitation of voltage changes, voltage uctuations and icker in
public low-voltage supply systems, for equipment with rated current ≤16 A per phase
and not subject to conditional connection
– Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test
– Part 4-3: Testing and measurement techniques - Radiated, radio-frequency,
electromagnetic eld immunity test
– Part 4-4: Testing and measurement techniques - Electrical fast transient/burst
immunity test
– Part 4-5: Testing and measurement techniques - Surge immunity test
– Part 4-6: Testing and measurement techniques - Immunity to conducted disturbances,
induced by radio-frequency elds
– Part 4-8: Testing and measurement techniques - Power frequency magnetic eld
immunity test
– Part 4-11: Testing and measurement techniques - Voltage dips, short interruptions
and voltage variations immunity tests

Compliance Information 4
394B
EC Declaration of Conformity - EMC
Compliance was demonstrated to the following specications listed in the Ocial Journal of the European
Communities: EMC Directive 2014/30/EU.
EN 61010 Safety requirements for electrical equipment for measurement, control, and
laboratory use
– Part 1: General requirements
– Part 2-030: Particular requirements for testing and measuring circuits
– Part 2-033: Particular requirements for hand-held multimeters and other meters, for
domestic and professional use, capable of measuring mains voltage
EN 61326 Electrical equipment for measurement, control and laboratory use - EMC
requirements
– Part 1: General requirements
– Part 2-1: Particular requirements - Test congurations, operational conditions
and performance criteria for sensitive test and measurement equipment for EMC
unprotected applications
– Part 2-2:Particular requirements - Test congurations, operational conditions and
performance criteria for portable testing, measuring and monitoring equipment used
in low-voltage distribution systems
EN 55011:2016+A1:2017 Industrial, scientic and medical equipment. Radio-frequency
disturbance characteristics. Limits and methods of measurement

Compliance Information 5
IEC 61000 Electromagnetic compatibility (EMC)
– Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test
– Part 4-3: Testing and measurement techniques - Radiated, radio-frequency,
electromagnetic eld immunity test
– Part 4-4: Testing and measurement techniques - Electrical fast transient/burst
immunity test
– Part 4-5: Testing and measurement techniques - Surge immunity test
– Part 4-6: Testing and measurement techniques - Immunity to conducted disturbances,
induced by radio-frequency elds
– Part 4-8: Testing and measurement techniques - Power frequency magnetic eld
immunity test

Compliance Information 6
IEC Measurement Category & Pollution Degree Denitions
Measurement Category (CAT) - classication of testing and measuring circuits according to the types
of mains circuits to which they are intended to be connected.
Measurement Category other than II, III, or IV : circuits that are not directly connected
to the mains supply.
Measurement Category II (CAT II) : test and measuring circuits connected directly to
utilization points (socket outlets and similar prints) of the low-voltage mains installation.
Measurement Category III (CAT III) : test and measuring circuits connected to the
distribution part of a building’s low-voltage mains installation.
Measurement Category IV (CAT IV) : test and measuring circuits connected at the
source of the building’s low-voltage mains installation.
Mains Isolated : is for measurements performed on circuits not directly connected to a
mains supply.
Pollution - addition of foreign matter, solid, liquid, or gaseous (ionized gases) that may produce a
reduction of dielectric strength or surface resistivity.
Pollution Degree 2 (P2) - only non-conductive pollution occurs except that occasionally a
temporary conductivity caused by condensation is expected

Compliance Information 7
Product End-of-Life Handling
The equipment may contain substances that could be harmful to the environment or human health if
improperly handled at the product’s end of life. To avoid release of such substances into the environment
and to reduce the use of natural resources, we encourage you to recycle this product to an appropriate
system that will ensure that most of the materials are reused or recycled appropriately.
This product is subject to Directive 2012/19/EU of the European Parliament and the
Council of the European Union on waste electrical and electronic equipment (WEEE), and
in jurisdictions adopting that Directive, is marked as being put on the market after August
13, 2005, and should not be disposed of as unsorted municipal waste. Please utilize your
local WEEE collection facilities in the disposition of this product.
Terms and Symbols
Terms
A caution statement calls attention to an operating procedure,
practice, or condition, which, if not followed correctly, could result
in damage to or destruction of parts or the entire product.
A warning statement calls attention to an operating procedure,
practice, or condition, which, if not followed correctly, could result
in injury or death to personnel.
A note statement calls attention to an operating procedure, practice, or condition,
which, should be noted before proceeding.

Compliance Information 8
Symbols
WARNING - Risk of electric shock.
CAUTION – Statements or instructions that must be consulted in
order to nd out the nature of the potential hazard and any actions
which must be taken.
Equipment protected by double or reinforced insulation
Battery
AC measurement
DC measurement
Fuse
Earth (ground) TERMINAL - Refer to the instructions accompanying this symbol
in this manual.

Safety Notices
The following safety precautions apply to both operating and maintenance personnel and must be followed
during all phases of operation, service, and repair of this instrument.
Before applying power to this instrument:
• Read and understand the safety and operational information in this manual.
• Apply all the listed safety precautions.
• Verify that the voltage selector at the line power cord input is set to the correct line voltage. Operating
the instrument at an incorrect line voltage will void the warranty.
• Make all connections to the instrument before applying power.
• Do not operate the instrument in ways not specied by this manual or by B&K Precision.
Failure to comply with these precautions or with warnings elsewhere in this manual violates the safety
standards of design, manufacture, and intended use of the instrument. B&K Precision assumes no
liability for a customer’s failure to comply with these requirements.
Electrical Power
This instrument is intended to be powered from a CATEGORY II mains power environment. The mains
power should be 115 V RMS or 230 V RMS. Use only the power cord supplied with the instrument and
ensure it is appropriate for your country of use.
Do not use this instrument in an electrical environment with a
higher category rating than what is specied in this manual for this
instrument.
You must ensure that each accessory you use with this instrument
has a category rating equal to or higher than the instrument’s
category rating to maintain the instrument’s category rating. Failure
to do so will lower the category rating of the measuring system.

Safety Notices 10
Ground the Instrument
To minimize shock hazard, the instrument chassis and cabinet must
be connected to an electrical safety ground. This instrument is
grounded through the ground conductor of the supplied, three-
conductor AC line power cable. The power cable must be plugged
into an approved three-conductor electrical outlet. The power jack
and mating plug of the power cable meet IEC safety standards.
Do not alter or defeat the ground connection. Without the safety
ground connection, all accessible conductive parts (including
control knobs) may provide an electric shock. Failure to use a
properly-grounded approved outlet and the recommended three-
conductor AC line power cable may result in injury or death.
Unless otherwise stated, a ground connection on the instrument’s
front or rear panel is for a reference of potential only and is not
to be used as a safety ground. Do not operate in an explosive or
ammable atmosphere.

Safety Notices 11
Environmental Conditions
This instrument is intended to be used in an indoor pollution degree 2 environment. The operating
temperature range is 0∘C to 40∘C and 20% to 80% relative humidity, with no condensation allowed.
Measurements made by this instrument may be outside specications if the instrument is used in non-
oce-type environments. Such environments may include rapid temperature or humidity changes, sunlight,
vibration and/or mechanical shocks, acoustic noise, electrical noise, strong electric elds, or strong
magnetic elds.
Do not operate the instrument in the presence of ammable gases or
vapors, fumes, or nely-divided particulates.
The instrument is designed to be used in oce-type indoor
environments. Do not operate the instrument
• In the presence of noxious, corrosive, or ammable fumes,
gases, vapors, chemicals, or nely-divided particulates.
• In relative humidity conditions outside the instrument’s
specications.
• In environments where there is a danger of any liquid being
spilled on the instrument or where any liquid can condense on
the instrument.
• In air temperatures exceeding the specied operating temperatures.
• In atmospheric pressures outside the specied altitude limits or
where the surrounding gas is not air.
• In environments with restricted cooling air ow, even if the air
temperatures are within specications.
• In direct sunlight.

Safety Notices 12
Do not operate instrument if damaged
If the instrument is damaged, appears to be damaged, or if any
liquid, chemical, or other material gets on or inside the instrument,
remove the instrument’s power cord, remove the instrument from
service, label it as not to be operated, and return the instrument to
B&K Precision for repair. Notify B&K Precision of the nature of any
contamination of the instrument.
Hazardous voltages may be present in unexpected locations in
circuitry being tested when a fault condition in the circuit exists.
Clean the instrument only as instructed
Do not clean the instrument, its switches, or its terminals with
contact cleaners, abrasives, lubricants, solvents, acids/bases,
or other such chemicals. Clean the instrument only with a clean
dry lint-free cloth or as instructed in this manual. Not for critical
applications.

Safety Notices 13
Do not touch live circuits
Instrument covers must not be removed by operating personnel.
Component replacement and internal adjustments must be made
by qualied service-trained maintenance personnel who are aware
of the hazards involved when the instrument’s covers and shields
are removed. Under certain conditions, even with the power cord
removed, dangerous voltages may exist when the covers are
removed.
To avoid injuries, always disconnect the power cord from the instrument, disconnect all other connections
(for example, test leads, computer interface cables, etc.), discharge all circuits, and verify there are
no hazardous voltages present on any conductors by measurements with a properly-operating voltage-
sensing device before touching any internal parts. Verify the voltage-sensing device is working properly
before and after making the measurements by testing with known-operating voltage sources and test for
both DC and AC voltages.
Do not attempt any service or adjustment unless another person capable of rendering rst aid and
resuscitation is present.
General Safety
Do not insert any object into an instrument’s ventilation openings or
other openings.
This instrument is not authorized for use in contact with the human
body or for use as a component in a life-support device or system.

Safety Notices 14
Servicing
Do not substitute parts that are not approved by B&K Precision or
modify this instrument. Return the instrument to B&K Precision for
service and repair to ensure that safety and performance features
are maintained.
Fuse replacement must be done by qualied service-trained
maintenance personnel who are aware of the instrument’s fuse
requirements and safe replacement procedures. Disconnect the
instrument from the power line before replacing fuses. Replace
fuses only with new fuses of the fuse types, voltage ratings, and
current ratings specied in this manual or on the back of the
instrument. Failure to do so may damage the instrument, lead to a
safety hazard, or cause a re. Failure to use the specied fuses will
void the warranty.
For continued safe use of the instrument
• Do not place heavy objects on the instrument.
• Do not obstruct cooling air ow to the instrument.
• Do not place a hot soldering iron on the instrument.
• Do not pull the instrument with the power cord, connected probe, or connected test lead.
• Do not move the instrument when a probe is connected to a circuit being tested.

Contents
Compliance Information 2
390B, 391B, & 393B 2
394B 4
IEC Measurement Category & Pollution Degree Denitions 6
Product End-of-Life Handling 7
Terms and Symbols 7
Safety Notices 9
1 General Information 17
1.1 Product Overview 17
1.2 Contents 18
1.3 Front Panel Overview 19
1.3.1 Push Buttons 20
2 Making Basic Measurements 21
2.1 Measuring AC /DC Voltage 22
2.1.1 High Frequency Reject Mode 23
2.1.2 Making dB Measurements AC mV only 24
2.2 Measuring Resistance 25
2.2.1 Testing for Continuity 26
2.2.2 Testing Diodes 27
2.2.3 Measuring Capacitance 28
2.3 Measuring AC / DC Current 29
2.4 Measuring Frequency 31
2.5 Measuring Temperature ∘C∘F 32
3 Functions 33
3.1 Store and Recall Functions 34
3.2 MAX MIN AVG 35
3.3 Relative Mode 35
3.4 Digit 36
3.5 Auto Hold 36
3.6 Peak Hold 36
3.7 Data Log and Log Rate 37
3.8 Auto Backlight 37
3.9 Power Up Option 37
4 Process Multimeter Functions 38
4.1 DC Current Output 39

16
4.1.1 Adjustable DC Current Output 40
4.1.2 Auto DC Current Output 40
4.2 Source Mode 41
4.3 Simulation Mode 42
4.4 Loop Power 43
4.4.1 250Ω HART 43
5 Battery and Fuse Replacement 44
6 Specications 45
7 Service Information 49
8 LIMITED THREE-YEAR WARRANTY 50

General Information
1.1 Product Overview
The 390B Series True RMS multimeters oer a comprehensive solution for general purpose measurement
applications. Bundled with a complete set of accessories, these multimeters provide technicians and
engineers with accurate results, data logging capabilities, and measurement features for evaluating a
variety of electronics or electrical systems.
Advanced features like data logging records measurements to the meter’s internal memory at a user-
specied sampling interval.
True RMS Handheld Digital Multimeters
390B Series
2bkprecision.com
Preliminary
Operation highlights
Auto on/off backlit display sensor
Low pass filter to minimize
high frequency noise
Quick manual range adjustment
True RMS AC and AC+DC
Optical isolated USB interface
for PC connectivity
Included accessories
These multimeters include test leads, K-type
thermocouple, magnetic hanger strap, and USB
communication cable.
Features 390B 391B 393B
True RMS AC, AC + DC voltage and current
DCV Accuracy ± (0.03% + 10 digits) ± (0.03% + 20 digits) ± (0.015% + 20 digits)
Display Count 40,000 40,000 100,000
AutoV/LoZ ✔- -
Auto Backlit, Dual Display ✔
Analog Style Bar Graph ✔
Relative Mode (% and Δ)✔
Min/Max/Avg ✔
dBm/dB measurement ✔
Auto Hold, Peak Hold ✔
Data Log Capacity 40,000 readings 20,000 readings 20,000 readings
Duty Cycle - ✔ ✔
Temperature Probe ✔
Optical Isolated USB
Interface ✔
Table 1.1 390B Series Models

General Information 18
Figure 1.1 390B
1.2 Contents
Please inspect the instrument mechanically and electrically upon receiving it. Unpack all items from the
shipping carton, and check for any obvious signs of physical damage that may have occurred during
transportation. Report any damage to the shipping agent immediately.
Save the original packing carton for possible future reshipment. Every instrument is shipped with the
following contents:
• 390B series DMM
• test leads
• K-type thermocouple (not included with 394B model)
• magnetic hanger strap
• USB communication cable
Verify that all items above are included in the shipping container. If anything is
missing, please contact B&K Precision.

General Information 19
1.3 Front Panel Overview
Figure 1.2 Front Panel
Item Name Description
1 Light Sensor Auto backlight sense point.
2 Display 40,000 /100,000 count dual display
3 Push Buttons Push buttons. Refer to table 1.3 for more information.
4 Rotary Switch Switches between the available operation modes.
5 Input Terminal Input terminal for voltage, frequency, resistance, continuity,
diode, capacitance and temperature measurements.
6 Return Terminal Return terminal for all measurements.
7 mA Input Terminal Input terminal for 0 to 400mA current measurements.
8 A Input Terminal Input terminal for 0 to 10A current measurements.
Table 1.2 Front Panel Overview

General Information 20
1.3.1 Push Buttons
Button Description
Shift Select measurement function.
RANGE Select measurement range. Press > 1 sec to enter auto range mode.
HFR Enable/Disable the High Frequency Reject mode for AC measurements.
Link Enable/Disable the link mode. (390B only)
Digit Selects the display digit.
Hz Measures the frequency for voltage or current. (394B only)
ENTER Enter menu function in pointer position.
CANCEL Cancel current menu function.
A-HOLD Enable/Disable the Auto-Hold mode.
P-HOLD
Enable the Peak-Hold mode in the AC or DC measurements. In this mode,
press button to select Peak-Hold MAX or MIN. Press > 1 sec to disable the
Peak-Hold mode.
REL ΔEnable/Disable the relative mode. (394B only)
Table 1.3 Push Buttons