METREL MD 9273 User manual

MD 9273 Bluetooth® TRMS Leakage Clamp with Power
Functions
MD 9273
Instruction manual
Bedienungsanleitung
Version 1.1.5; Code 20753096
KOMETEC Karl Oelkers e.K.
Mess- und Prüfgeräte · Shop
Mozartstr. 10 · D-88097 Eriskirch
T: 07541 / 955-1313 · F: 07541 / 955-1131
[email protected] · www.kometec.de

2
Distributor:
METREL d.d.
Ljubljanska cesta 77
1354 Horjul
Slovenia
E-mail: [email protected]
Website: http://www.metrel.si/
Metrel GmbH
Mess und Prüftechnik
Orchideenstrasse 24
90542 Eckental -Brand
Germany
E-mail: [email protected]
Internet: http://www.metrel.de/
Metrel UK
Test & Measurement
Unit 16, 1st Qtr Business Park Blenheim Road
Epsom
Surrey
KT19 9QN
GREAT BRITAIN
E-mail: [email protected]
Website: http://www.metrel.co.uk/
© 2022 METREL

3
Mark on your equipment certifies that this equipment meets the requirements of all EU
(European Union) related regulations.
Die Kennzeichnung auf Ihrem Gerät bestätigt, dass dieses Gerät den Anforderungen
aller EU-bezogenen Vorschriften entspricht.
Hereby, Metrel d.d. declares that the MI 3155 is in compliance with Directive
2014/53/EU (RED) and all other subjected EU directive. The full text of the EU
declaration of conformity is available at the following internet address
https://www.metrel.si/DoC.
Hiermit erklärt Metrel d.d., dass der MI 3155 der Richtlinie 2014/53/EU (ROT) und allen
anderen unterliegenden EU-Richtlinien entspricht. Text der EU-Konformitätserklärung
ist unter der folgenden Internetadresse https://www.metrel.si/DoC verfügbar.
Mark on your equipment certifies that it meets requirements of all subjected UK
regulations.
Das Kennzeichen auf Ihrem Gerät bescheinigt, dass es die Anforderungen aller
unterworfenen britischen Vorschriften erfüllt.
Hereby, Metrel d.d. declares that the MD 9273 is in compliance with Radio Equipment
Regulations 2017 and all other subjected UK regulations. The full text of the UK
declaration of conformity is available at the following internet address
http://www.metrel.si/UK-DoC.
Hiermit erklärt Metrel d.d., dass der MD 9273 den Radio Equipment Regulations 2017
und allen anderen unterliegenden britischen Vorschriften entspricht. Text der UK-
Konformitätserklärung ist unter der folgenden Internetadresse
https://www.metrel.si/DoC verfügbar
No part of this publication may be reproduced or utilized in any form or by any means without permission in
writing from METREL.
Es darf kein Teil dieser Veröffentlichung vervielfältigt oder in irgendeiner Form auf irgendeinem Wege genutzt
werden, ohne die schriftliche Genehmigung von METREL.

MD 9273 Leakage clamp Table of contents/ Inhaltsverzeichnis
4
TABLE OF CONTENTS/INHALTSVERZEICHNIS
English
1General Instructions...........................................................................................................................6
1.1 Safety measures ..........................................................................................................................6
2Instrument Description.......................................................................................................................8
2.1 Rotary Function switch........................................................................................................................9
3Description of Test Functions .........................................................................................................13
3.1 Main Test function connection schemes ....................................................................................13
3.2 Flowcharts of sub-function selection ..........................................................................................14
3.3 Test functions.............................................................................................................................15
3.4 Data hold mode..........................................................................................................................21
3.5 Bluetooth®Mode Functions........................................................................................................22
4Technical Specifications..................................................................................................................23
4.1 General specifications –Environment conditions.......................................................................23
4.2 Measurement specifications.......................................................................................................23
5Maintenance......................................................................................................................................28
6LIMITED WARRANTY........................................................................................................................29
Appendix A MD 9273 as an Adapter of Master Instrument .................................................................30
A.1 Establishing Bluetooth®Communication ....................................................................................30
A.2 Managing Tests with MD 9273 Adapter .....................................................................................31
A.3 Single Tests with MD 9273 Adapter...........................................................................................32
Appendix B P –Online power measurement .......................................................................................32
Appendix C U –Online voltage measurement .....................................................................................33
Appendix D I –Online current measurement.......................................................................................34
Appendix E Imax –Inrush Current Recording .......................................................................................35
Appendix F hn–Voltage harmonics test..............................................................................................38
Appendix G hn–Current harmonics test..........................................................................................39
Appendix H E –Events ..........................................................................................................................40
Appendix I LOG –U, I, P, E Logger .....................................................................................................40

MD 9273 Leakage clamp Table of contents/ Inhaltsverzeichnis
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Deutch
1Allgemeine Anweisungen.................................................................................................................41
1.1 Sicherheitsmaßnahmen .............................................................................................................41
2Gerätebeschreibung.........................................................................................................................43
2.1 Drehfunktionsschalter........................................................................................................................44
3Beschreibung der Prüffunktionen...................................................................................................48
3.1 Anschlussbilder für die Hauptprüffunktion..................................................................................48
3.2 Flussdiagramme der Unterfunktionsauswahl .............................................................................49
3.3 Prüffunktionen............................................................................................................................50
3.4 Datenhaltemodus.......................................................................................................................56
3.5 Funktionen im Bluetooth®-Modus...............................................................................................57
4Technische Daten .............................................................................................................................59
4.1 Allgemeine Spezifikationen –Umweltbedingungen....................................................................59
4.2 Messspezifikationen...................................................................................................................59
5Wartung .............................................................................................................................................64
6BEGRENZTE GEWÄHRLEISTUNG ..................................................................................................65
Anhang A MD 9273 als Adapter eines Hauptgeräts..........................................................................66
A.1 Einrichten einer Bluetooth®-Kommunikation...............................................................................66
A.2 Handhabung von Prüfungen mit dem MD 9273 Adapter............................................................67
A.3 Einzelprüfungen mit dem MD 9273 Adapter...............................................................................68
Anhang B P –Online-Leistungsmessung .........................................................................................68
Anhang C U –Online-Spannungsmessung.......................................................................................69
Anhang D I –Online-Strommessung .................................................................................................71
Anhang E Imax –Aufzeichnung des Einschaltstroms .......................................................................72
Anhang F hn–Prüfung der Spannungsharmonischen....................................................................73
Anhang G hn–Prüfung der Stromharmonischen.............................................................................75
Anhang H E –Ereignisse....................................................................................................................76
Anhang I LOG –U, I, P, E Logger .........................................................................................................76

MD 9273 Leakage clamp General Instructions
6
1General Instructions
This instrument has been designed in accordance with IEC 61010 series standards that regulates safety
requirements for the electronic measuring equipment and current measuring clamps. Present user manual
shall be read carefully in order to get the best out of this equipment. Safety instructions shall always be
complied with.
1.1Safety measures
General
•If the clamp-meter is used in a manner not specified in this user’s manual, the protection provided
by the equipment may be impaired!
•This equipment can be used to carry out measurements in the CAT III
1
600V environment.
•When using this clamp meter, the user should comply with all the safety measures regarding:
−Protection against the electric current hazards.
−Protection of the clamp A-meter against incorrect use.
−Protection against electric shock hazard.
•For operator security, only the test probes supplied with the instrument shall be used.
•Do not use the clamp-meter and its accessories if any damage is noticed on them!
During use
•Before carrying out any measurements, the instrument shall be warmed up for at least 30 seconds.
•If the clamp-meter is used near any high level noise generating equipment, the reading might
become unstable or show significant errors.
•The maximum limits of the input values stated in the technical specifications tables shall not be
exceeded to avoid damage to the equipment.
•The rotary switch shall be in the correct position before starting a new measurement.
•Practice extreme caution when working near bare conductors.
•Any accidental contact with the bare conductor may cause an electric shock.
•Use caution when working with voltages higher than 60V DC or 30V AC RMS to avoid a risk of
electric shock.
•The test probe(s) shall be disconnected from the circuit under test before changing the function.
•During measurement fingers shall always be kept behind the protection ring, see ChapterInstrument
Description.
•The battery shall be changed when the symbol is shown in order to avoid incorrect
measurement readings.
Symbols
The symbols used in this manual and in the equipment are as follows:
1
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.

MD 9273 Leakage clamp General Instructions
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Warning: check the instruction manual. Any incorrect use may cause damage to the equipment or
its components.
Earth
Complies with European Union Directives.
Complies with UK regulations.
This equipment has double insulation.
Allows use with dangerous voltage conductors.
Instructions
•Before opening the equipment, the instrument shall be disconnected from any source of electric
supply and it shall be ensured that the operator is free from static electricity, as it could destroy the
internal components.
•Before using this equipment it shall be checked for proper operation; by turning the rotary switch to
A or V position and verifying a double beep and the display activity.
•Any adjustment, repair or maintenance work on the clamp meter must only be carried out by a
qualified person, always taking into account the instructions included in this manual.
•A “qualified person” means one familiar with the installation, construction and operation of the
equipment, and with the risks implied. This person should be trained and authorized to charge and
discharge energy from the circuits and the equipment in accordance with established practice.
•When the equipment is open, some internal components can retain dangerous power, even after the
equipment has been disconnected from the mains electricity supply.
•In the case of abnormal operation and/or performance, the equipment shall not be used until it has
been repaired/verified.
•The battery shall be removed from the clamp-meter if it is not going to be used for a long period, and
shall not be stored in a hot or humid environment.
WARNING
This equipment is designed according to EMC standards for portable test and measurement instruments.
However, it is recommended to disconnect the test leads during current measurements, as a high level of
radiofrequency electromagnetic field might be present, which can negatively affect the accuracy of the
measurement.

MD 9273 Leakage clamp Instrument Description
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2Instrument Description
Becoming familiar with the equipment
1. Transformer jaws
2. Protection ring
3. Jaw opening trigger
4. Rotary function switch
5. Keyboard
6. LCD display
7. Terminals
Transformer clamps
Capture the AC current flowing through the conductor. DC current cannot be measured.
1
2
3
4
5
6
7

MD 9273 Leakage clamp Instrument Description
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2.1 Rotary Function switch
It is intended to switch-on clamps and select basic test function or activate BT communication as described
in Table 1.
Position
Function
OFF
OFF position.
A
Measurement of AC current up to 100 A.
V
Measurement of AC or DC voltage up to 600 V.
W
Measurement of power of up to 60 kVA, with limits of 100 A and 600 V.
Activates the Bluetooth® Mode to communicate with Metrel instruments.
Table 1: Rotary switch position functions
Keyboard
The keyboard consists of four multifunctional push buttons. Table 2 describes the function of each one.
Key
Use
Function
F –Function
Any position of the rotary
switch
Function selection key. Depending on the rotary switch
position, the functions will vary. See Chapter
Description of Test Functions for details.
Pressing this button cycles through the various
functions.
Hz –Frequency
A and V position of the
rotary switch, in the RMS
function only
When pressed for more than 2 s, it alternates the
second display information between THD and Hz.
H –Hold
Any position of the rotary
switch and all the
functions except in PEAK
function
When pressed the data hold mode is turned on and the
screen information stops updating.
On next press, the MAX mode is turned on for the
register of maximum values.
On third press, the MIN mode is accessed for the
register of minimum values.
Press again to return to the normal mode.
Light
Any position of the rotary
switch, in all the functions
With a long press of the key (more than 2 s) the LCD
screen back-light is lit. 30 s after any button was
pressed, it switches off automatically.
Auto
A and V position of the
rotary switch, in the RMS
function only
Cycles through the different manual ranges until the
Autorange is active again.

MD 9273 Leakage clamp Instrument Description
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+
A and V position, in the
harmonic measurement
function
Increases the displayed harmonic number.
AC/DC
V position, in the RMS
function only
Alternates between V AC or V DC measurements.
VFD
V position, in the RMS
function only
Calculates the RMS voltage of Variable Frequency
Drive generators.
-
A and V positions, in the
harmonic measurement
function
Decreases the number of harmonic to be measured.
Table 2: Keyboard push buttons function description
LCD Screen
Figure 2.1: Test results and indication presentation on LCD screen
Data hold indication.
Maximum reading indication.
Minimum reading indication.
PEAK
Peak reading indication. See chapter Description of Test Functions.
Phase angle measurement function of the current in reference to the voltage.
Indicates that the current is ahead the voltage.
Indicates that the current is behind the voltage.

MD 9273 Leakage clamp Instrument Description
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Indicates a loss, possibly due to insulation defects; only in the mA measurement
mode.
Indicates a loss, possibly due to insulation defects and accumulation of non-lineal
loads; only in the mA measurement mode.
Indicates a loss, possibly due to a high accumulation of non-lineal loads; only in the
mA measurement mode.
Indicates that the measured magnitude is expressed as a true effective value.
CF
Measuring the crest factor.
AC
AC input indication.
DC
DC input indication.
mA, A
Milliamperes, amperes.
V
Volts.
VAr, kVAr
Reactive volt-amperes, reactive kilovolt-amperes; reactive power measuring units.
VA, kVA
Volt-amperes, kilovolt-amperes; apparent power measuring units.
W, kW
Watts, kilowatts; active power measuring units.
%
Indicates the measurement of a percent value.
THD
Total harmonic distortion ratio.
PF
Power factor.
INRUSH
Inrush current measurement function.
VFD
Voltage Frequency Drive filter function.
HARMONIC
Harmonic measurement function.
Hz
Frequency measurement function.
Instrument paired (Bluetooth® Mode)
Recording function (Bluetooth® Mode)
Data available to be downloaded (Bluetooth® Mode)
Indicates that range is selected automatically.
Full battery.
Medium battery.

MD 9273 Leakage clamp Instrument Description
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Low battery.
BLINK
Battery is close to empty.
Table 3: LCD screen indications
Inputs
Table 4 describes the inputs’function.
Input
Description
COM
Common reference for voltage and power measurements; use black probe.
V
Voltage and power measurements active line input; use red probe.
Table 4: Inputs
Standby Mode
If the clamp-meter is not in use for a period of 15 minutes, the screen goes blank and the clamp-meter goes
into standby mode. To wake the meter from standby mode, turn the rotary switch to OFF position and then
back to the desired function to reactivate the screen. The Standby mode is disabled during active Bluetooth®
connection with other instrument.
Standard accessories
•Test probes,
•Crocodile clamps,
•Batteries (2 AA 1,5V batteries),
•Instruction manual,
•Carrying Case.

MD 9273 Leakage Clamp Description of Test Functions
13
3Description of Test Functions
Main Test Functions of the Leakage Clamps, selectable with rotary switch position, are:
•Current test measurement –position mA, A
•Voltage test measurement - position V
•Power test measurement - position W
•In the position of the rotary switch, clamps are controlled by the connected device.
Beside Main test function, sub function test can be selected with keyboard buttons. See Chapter Flowcharts
of sub-function selection for details.
3.1 Main Test function connection schemes
Appropriate jaws and test leads connection schemes for each selected main function are presented on Figure
3.1: Test function connection schemes below.
mA, A –Current test
V –Voltage test
W –Power test
Figure 3.1: Test function connection schemes

MD 9273 Leakage Clamp Description of Test Functions
14
3.2Flowcharts of sub-function selection
The Figure 3.2: Flowcharts of sub function selection shows a flowchart of the keyboard navigation through
the different measuring sub functions for each of the three main function selected with rotary switch.
Sub-functions represented with squares are selected with sequentially pressing the F key and can be further
defined by pressing the keys marked with text next to the squares.
Figure 3.2: Flowcharts of sub function selection

MD 9273 Leakage Clamp Description of Test Functions
15
3.3Test functions
Measuring mA, A and V
The following sections describe the functions available in the current and voltage measurement modes
(positions of the rotary switch in mA, A and V). To select the desired function, the Fkey shall be pressed
repeatedly until it is selected. For current measurements (mA, A), it is recommended to disconnect the test
leads, except for the Inrush function where voltage can be measured (see “Warning” section).
TRMS value measurement function
TRMS is the effective value of the current or the voltage. Secondary reading on the display is the THD (total
harmonic distortion ratio) or the frequency of measured signal. THD is the ratio between the higher frequency
components of the signal with the essential component (at 50 Hz or 60 Hz), expressed as percentage. A high
THD value indicates high distortion of the measured signal whilst a 0%THD indicates a pure single-frequency
sinusoid. Data hold in this mode is possible as well as the register of maximum and minimum values using
the Hkey.
Frequency measurement
In this function, the frequency of the measured signal is displayed. Press Fbutton for more than 2 s while in
the TRMS measurement function to enter frequency measurement mode. To return to THD, press the same
button again for more than 2 s.

MD 9273 Leakage Clamp Description of Test Functions
16
Intelligent loss analysis (mA measurement only)
The clamp A-meter includes an algorithm that allows determining the cause for the current loss. This mode
is enabled only when measuring current in the mA range and TRMS measurement is selected. In the TRMS
measurement function, one or two icons will be shown on the screen informing of the possible reasons for
the loss.
Indicates that the loss is possibly due to a defect in the equipment insulation.
Indicates that the loss may be partially due to defects in the insulation and
partially to the accumulation of non-lineal loads.
Indicates that a loss is possibly due to a high accumulation of non-lineal
loads.
Harmonic analysis function and harmonic percent value
Harmonics (1 through to 19) can be measured as an absolute magnitude of the signal, or a percentage of
the fundamental (the 1st) harmonic. 1st harmonic is also called the fundamental frequency.
Absolute magnitude and percent value of the harmonics can be reached with F key while in voltage or current
rotary switch positions.
Initially the harmonic 1 is displayed but this can be changed using the + and - keys. The display shows the
percent of effective value, or an absolute harmonic value, together with the harmonic number (at the bottom
of the screen).
For example, if there is a 50 Hz network frequency and the absolute value of the 3rd harmonic is measured,
this is measuring the magnitude (current or voltage) of the 150 Hz component.
In this mode, data hold and registering of maximum and minimum values is possible by using the Hkey.
Crest factor function
Measures crest factor of the input signal. The crest factor is the ratio of the peak and the effective (or TRMS)
value of a waveform. For a sinusoidal wave the crest value is 1.41. The greater the difference between the
peak and efficient RMS value, the higher the crest factor is.
In this mode, data retention and registering of maximum and minimum values is possible by using the Hkey.

MD 9273 Leakage Clamp Description of Test Functions
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In this mode, data retention and registering of maximum and minimum values is possible by using the Hkey.
Peak hold function
In this function, the peak value of the waveform is shown. The peak value is the highest measured value
within one period of the waveform and is usually higher than the effective value (also known as the TRMS
value), e.g. for a perfect sinusoidal signal the peak value is 1.41 times the effective value. Peak hold is
executed with a faster sampling than other measurements at 25 µs.
Inrush Current measurement (Current functions only)
Inrush current is the maximum instantaneous current drawn by a circuit when first turned on, expressed as
TRMS value. It is meant for use with motors and other loads that draw high initial current.
Additionally it is possible to connect the voltage probes and the instrument calculates the minimum RMS
voltage of the initial signal.

MD 9273 Leakage Clamp Description of Test Functions
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128 Hz Current measurement (Current functions only)
There is a notch filter at 128 Hz frequency. The instrument filters the rest of frequency spectrum out. This
function is used in conjunction with other Metrel®Instruments or a signal generator for cable tracking.
DC measurement (Voltage functions only)
In this function, the DC value of the waveform is shown. This mode is entered by pressing the AC/DC button
in the TRMS measurement function screen. To change back to AC, press the same button again.

MD 9273 Leakage Clamp Description of Test Functions
19
VFD measurement (Voltage functions only)
In this function the instrument calculates the equivalent base frequency and RMS value of voltage pulses
generated by variable frequency drives. Press the AC/DC button in the TRMS measurement function screen
to enter this mode.
Manual range selection
By pressing the Auto button, the range changes from auto-range to the different ranges available. This
function can be used in V and A mode. When the auto-range is not active, the icon is not showed.
Measuring Power
In the following sections, the functions available in the power measuring mode (position W of the rotary
switch) will be described. To select the desired function the Fkey must be pressed repeatedly until the
required function is selected.
Active power measurement
Measurement of the active power together with measurement of the power factor are shown on the screen.
If the load is inductive, the symbol will appear on the screen; if the load is capacitive, the symbol
will appear on screen.

MD 9273 Leakage Clamp Description of Test Functions
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Position of the voltage terminals and the jaw is taken into account; the red terminal should be connected to
the line terminal and the jaw should be connected so that the current flows towards the load in the direction
indicated on the jaw. The instrument faces the source. In this mode, data hold and registering of maximum
and minimum values is possible by using the Hkey.
Reactive Power Measurement
Measurement of the reactive power is shown together with the measurement of the power factor. If the load
is inductive, the symbol will appear on the screen and if the load is capacitive, the symbol will
appear on screen.
Position of the voltage terminals and the jaw is taken into account; the red terminal should be connected to
the line terminal and the jaw should be connected so that the current flows towards the load in the direction
indicated on the jaw. In this mode, data hold and registering of maximum and minimum values is possible by
using the Hkey.
Apparent Power Measurement
Measurement of the apparent power together with the measurement of the power factor are shown, if the
load is inductive, the symbol will appear on the screen and if the load is capacitive, the symbol
will appear on screen.