METREL MD 9250 User manual

METREL MD 9250
Industrial TRMS AC/DC CAT IV 1000 V
MD 9250
User Manual
Bedienungsanleitung
Version 1.1, Code no. 20 752 003

2
Distributor:
METREL d.d.
Ljubljanska cesta 77
1354 Horjul
Slovenia
e-mail: [email protected]
web site: 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 Ltd.
Test & Measurement
Unit 16, 1st Qtr Business Park
Blenheim Road
Epsom
Surrey
KT19 9QN,
Great Britain
E-mail: [email protected]
Internet: http://www.metrel.co.uk
© 2012 –2016 METREL
Mark on your equipment certifies that this equipment meets the requirements of the EC
(European Community) regulations concerning safety and electromagnetic compatibility.
No part of this publication may be reproduced or utilized in any form or by any means
without permission in writing from METREL.

MD 9250 Clamp Meter Series Table of contents / Inhalt
3
Table of contents/ Inhalt
English
1 Safety ...........................................................................................................................4
2 Cenelec Directives........................................................................................................6
3 Product Description ......................................................................................................7
4 Operation......................................................................................................................8
5 Specifications..............................................................................................................16
6 Maintenance...............................................................................................................21
Deutsch
1 Sicherheitsbestimmungen ..........................................................................................23
2 Cenelec-Richtlinien.....................................................................................................24
3 Produktbeschreibung..................................................................................................25
4 Betrieb........................................................................................................................26
5 Spezifikationen ...........................................................................................................34
6 Wartung......................................................................................................................39

MD 9250 Clamp Meter Series Safety
4
1 Safety
MaintenanceThis manual contains information and warnings that must be followed for
operating the instrument safely and maintaining the instrument in a safe operating
condition. If the instrument is used in a manner not specified by the manufacturer, the
protection provided by the instrument may be impaired.
The meter protection rating, against the users, is double insulation per IEC/EN61010-1
2nd Ed., UL61010-1 2nd Ed., CAN/CSA C22.2 No. 61010.1-0.92, IEC/EN61010-2-032,
UL61010B-2-032, CAN/CSA C22.2 No. 61010-2-032-04 & IEC/EN61010-
031:2002/A1:2008:
Measurement Category IV 1000V AC & DC.
PER IEC61010 OVERVOLTAGE INSTALLATION CATEGORY
OVERVOLTAGE CATEGORY II
Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be
supplied from the fixed installation.
Note –Examples include household, office, and laboratory appliances.
OVERVOLTAGE CATEGORY III
Equipment of OVERVOLTAGE CATEGORY III is equipment in fixed installations.
Note –Examples include switches in the fixed installation and some equipment for
industrial use with permanent connection to the fixed installation.
OVERVOLTAGE CATEGORY IV
Equipment of OVERVOLTAGE CATEGORY IV is for use at the origin of the installation.
Note –Examples include electricity meters and primary over-current protection
equipment.
TERMS IN THIS MANUAL
WARNING identifies conditions and actions that could result in serious injury or even
death to the user.
CAUTION identifies conditions and actions that could cause damage or malfunction in
the instrument.
WARNING
To reduce the risk of fire or electric shock, do not expose this product to rain or moisture.
The meter is intended only for indoor use.
To avoid electrical shock hazard, observe the proper safety precautions when working
with voltages above 60 VDC or 30 VAC rms. These voltage levels pose a potential
shock hazard to the user.
Keep your hands/fingers behind the hand/finger barriers (of the meter and the test leads)
that indicate the limits of safe access of the hand-held part during measurement.
Inspect test leads, connectors, and probes for damaged insulation or exposed metal
before using the instrument. If any defects are found, replace them immediately.

MD 9250 Clamp Meter Series Safety
5
This Clamp-on meter is designed to apply around or remove from uninsulated
hazardous live conductors. But still, individual protective equipment must be used if
hazardous live parts in the installation where measurement is to be carried out could be
accessible.
CAUTION
Disconnect the test leads from the test points before changing meter functions.
INTERNATIONAL ELECTRICAL SYMBOLS
!
Caution ! Refer to the explanation in this Manual
Caution ! Risk of electric shock
Earth (Ground)
Double Insulation or Reinforced insulation
Fuse
AC--Alternating Current
DC--Direct Current
Application around and removal from hazardous live conductors is
permitted

MD 9250 Clamp Meter Series Cenelec Directives
6
2 Cenelec Directives
The instruments conform to CENELEC Low-voltage directive 2006/95/EC and
Electromagnetic compatibility directive 2004/108/EC

MD 9250 Clamp Meter Series Product Description
7
3 Product Description
This user's manual uses only representative model(s) for illustrations. Please refer
specification details for function availability to each model.
1) Antenna for Non-Contact EF-
Detection
2) Hand/Finger Barrier to indicate
the limits of safe access of the
meter during measurement
3) Rotary-switch Selector to turn
the power ON/OFF and Select a
function
4) Push-buttons for special
functions & features.
5) Input Jack for all functions
EXCEPT non-invasive DCA &
ACA current functions
6) Common (Ground reference)
Input Jack for all functions
EXCEPT non-invasive DCA &
ACA current functions
7) 3-5/6 digits 6000 counts & 3-
1/2 digits 2000 counts dual
numeric LCD display
8) Jaw trigger for opening the
clamp jaw
9) Jaw center (& DCA polarity)
Indicator, at where best DCA &
ACA accuracy is specified
10) Hall-effect Clamp Jaw for AC
& DC current magnetic field pick
up

MD 9250 Clamp Meter Series Operation
8
4 Operation
CAUTION: Before and after hazardous voltage measurements, test the voltage
function on a known source such as line voltage to determine proper meter
functioning.
AutoCheckTM mode
This innovative AutoCheckTM feature automatically selects measurement function of
ACVHz,DCV, or Resistance ()based on the input via test leads.
●With no input, the meter displays “Auto” when it is ready.
●With no voltage signal but a resistance below 10M(nominal) is present, the meter
displays the resistance value. When the resistance is below the “Audible Threshold”,
the meter further gives a continuity beep tone.
●When a signal above the voltage threshold of 1.5V DC or AC up to the rated 1000V
is present, the meter displays the voltage value in appropriate DCV or ACV,
whichever larger in peak magnitude.
Note:
*Range-Lock and Function-Lock Feature: When a measurement reading is being
displayed in AutoCheckTM mode, press the RANGE or SELECT button momentarily 1
time can lock the range or function it was in. Press the button momentarily repeatedly to
step through the ranges or functions.
*As Hazardous-Alert: When making resistance measurements in AutoCheckTM mode,
an unexpected display of voltage readings alerts you that the object under test is being
energized.

MD 9250 Clamp Meter Series Operation
9
*Ghost-voltage Buster: Ghost-voltages are unwanted stray signals coupled from
adjacent hard signals, which confuse common multimeter voltage measurements. Our
AutoCheckTM mode provides low (ramp-up) input impedance (approx. 2.5kΩ at low
voltage) to drain ghost voltages leaving mainly hard signal values on meter readings. It
is an invaluable feature for precise indication of hard signals, such as distinguishing
between hot and open wires (to ground) in electrical installation applications.
WARNING:
AutoCheckTM mode input impedance increases abruptly from initial 2.5kΩ to a few
hundred kΩ’s on high voltage hard signals. “LoZ” displays on the LCD to remind the
users of being in such low impedance mode. Peak initial load current, while probing
1000VAC for example, can be up to 566mA (1000V x 1.414 / 2.5kΩ), decreasing
abruptly to approx. 3.37mA (1000V x 1.414 / 420kΩ) within a fraction of a second. Do
not use AutoCheckTM mode on circuits that could be damaged by such low input
impedance. Instead, use rotary-switch selector or high input impedance voltage
modes to minimize loading for such circuits.
VFD-ACVHz & ACVHz functions
Inputs are made through the test leads terminals.
VFD-ACV Hz function is to deal with VFD (Variable Frequency Device) signals. It,
however, further pre-selects the most appropriate voltage-ranges and thus the Hz
trigger levels to best cope with most VFD-Voltage and VFD-Frequency applications.
Note: The Hz trigger level is determined by the AC/DC+AC Voltage or Current
function-range being in use. Press RANGE button to select different function-ranges
and thus trigger levels manually.
DCV & DC+ACVHz functions
Inputs are made through the test leads terminals. Defaults at DCV Function. Press
SELECT button momentarily and release to select DC+ACVHz.

MD 9250 Clamp Meter Series Operation
10
ACA Hz, DCA & DC+ACAHz functions
Input is made through the clamp jaws for non-invasive current measurements. Defaults
at ACA Hz Function. Press SELECT button momentarily and release to select the
subject functions in sequence.
CAUTION (Application and removal of the Clamp-on meter)
For non-invasive current measurements, press the jaw trigger and clamp the jaws
around conductor(s) of only one single pole of a circuit for load current measurement.
Make sure the jaws are completely closed, or else it will introduce measurement errors.
Enclosing conductor(s) of more than one pole of a circuit may result in differential
current (like identifying leakage current) measurement. Locate the conductor(s) at the
Jaws center as much as possible to get the best measuring accuracy. For removal,
press the jaw trigger and remove the jaws from the conductor(s).
Adjacent current-carrying devices such as transformers, motors and conductor wires will
affect measurement accuracy. Keep the jaws away from them as much as possible to
minimize influence.
Resistance & Continuity functions
Inputs are made through the test leads terminals. Defaults at Resistance. Press
SELECT button momentarily and release to select. Continuity
Capacitance & Diode functions
Inputs are made through the test lead terminals. Defaults at Capacitance. Press
SELECT button momentarily and release to select Diode.

MD 9250 Clamp Meter Series Operation
11
Note
When using Diode test function, normal forward voltage drop (forward biased) for a
good silicon diode is between 0.400V to 0.900V. A reading higher than that indicates a
leaky diode (defective). A zero reading indicates a shorted diode (defective). An OL
indicates an open diode (defective). Reverse the test leads connections (reverse
biased) across the diode. The digital display shows OL if the diode is good. Any other
readings indicate the diode is resistive or shorted (defective).
CAUTION
1. Using Resistance, Continuity, Diode or Capacitance function in a live circuit will
produce false results and may damage the meter. In many cases the suspected
component(s) must be disconnected from the circuit to obtain an accurate measurement
reading.
2. When using Capacitance function, discharge capacitor(s) before making any
measurements. Large value capacitors should be discharged through an appropriate
resistance load

MD 9250 Clamp Meter Series Operation
12
Temperature function
Defaults at oC(Celsius) readings. Press SELECT button momentarily and release to
select oF(Fahrenheit) readings. Inputs are made through the test leads terminals. Be
sure to insert the banana plug type-K temperature bead probe AMD 9023 with correct
polarities. You can also use a plug adapter AMD 9024 (Optional purchase) with
banana pins to type-K socket to adapt other type-K standard mini plug temperature
probes.
Electric Field EF-Detection
In Voltage or Current function, press the EF button for one second or more and release
to toggle to EF-Detection feature. The meter displays “E.F.” when it is ready. Signal
strength is indicated as a series of bar-graph segments on the display together with
variable beep tones.

MD 9250 Clamp Meter Series Operation
13
●Non-Contact EF-Detection: An antenna is located along the top-right end of the clamp
jaw, which detects electric field surrounds energized conductors. It is ideal for tracing
live wiring connections, locating wiring breakage and to distinguish between live or earth
connections.
●Probe-Contact EF-Detection: For more precise indication of live wires, such as
distinguishing between live and ground connections, use the Red (+) test probe for
direct contact measurements.
PC computer interface capabilities
The instrument equips with an optical isolated interface port at the meter back for
data communication. Optional purchase PC interface kit AMD 9250 is required to
connect the meter to the PC computer RS232 or USB ports. Press and hold the
HOLD button while turning the meter on to enable meter PC-COMM output.
Hold
The hold feature freezes the display for later view. Press the HOLD button momentarily
and release to toggle the hold feature.
5ms CREST-MAX capture mode
Press CREST (HOLD) button for one second or more and release to activate CREST-
MAX capture (Instantaneous Peak-Hold) mode to capture signal peak of voltage or
current in duration as short as 5ms. The LCD “C” & “MAX” turn on. Press again the
button momentarily and release can toggle the combination use of HOLD feature. Press
the button for 1 second or more and release to exit CREST-MAX capture mode. Auto-
ranging and Auto-Power-Off are disabled automatically in this mode.

MD 9250 Clamp Meter Series Operation
14
Backlighted LCD display
Press the SELECT button for 1 second or more to toggle the LCD backlight. The
backlight will also be turned off automatically after 32 seconds to extend battery life.
Relative-Zero ( ) mode
Relative-Zero allows the user to offset the meter consecutive measurements with the
main display displaying reading as the reference value. Press the REL button
momentarily and release to toggle Relative-Zero mode.
Manual or Auto-ranging
Press the RANGE button momentarily and release to select manual-ranging, and the
meter will remain in the range it was in, the LCD turns off. Press the button
again to step through the ranges. Press and hold the button for 1 second or more and
release to resume auto-ranging.
Note: Manual-ranging feature is not available in Hz and function ranges.
Set Beeper Off
Press the RANGE button while turning the meter on to temporarily disable the Beeper
feature. Turn the rotary switch OFF and then back on to resume.
Auto-Power-Off (APO)
The Auto-Power-Off (APO) mode turns the meter off automatically to extend battery life
after approximately 34 minutes of no rotary switch or push button operations. To wake
up the meter from APO, press the SELECT button momentarily and release or turn the
rotary switch OFF and then back on. Always turn the rotary switch to the OFF position
when the meter is not in use
Disabling Auto-Power-Off
Press and hold the SELECT button while turning the meter on to temporarily disable the
Auto-Power-Off (APO) feature. Turn the rotary switch OFF and then back on to resume.

MD 9250 Clamp Meter Series Operation
15
Relative Zero mode allows the user to offset the meter consecutive measurements
with the displaying reading as the reference value. The display will now show readings
relative to the stored reference value. That is, display = reading - stored value. Press
the button momentarily to toggle to the relative zero mode. The annunciator “ ”
turns on. The meter also enters manual ranging mode where available. The annunciator
“ ” turns off.
Display Backlight
Press the SELECT button for 1 second or more to toggle the display backlight on and
off.
Auto Power Off (APO)
When the meter is on, the Auto Power Off (APO) feature will switch the meter to sleep
mode automatically after approximately 30 minutes of neither slide-switch nor push
button operations to extend battery life. To wake up the meter from APO, press any
push-button momentarily or set the slide-switch to the OFF position and then slide back
on again. Always set the slide-switch to the OFF position manually when the meter is
not in use.

MD 9250 Clamp Meter Series Specifications
16
5 Specifications
Display: 3-5/6 digits 6000 counts. & 3-1/2 digits 1,999
counts for Hz
Polarity: Automatic
Update Rate: 5 per second nominal;
Operating Temperature: 0C to 40C
Relative Humidity: Maximum relative humidity 80% for temperature up
to 31C decreasing linearly to 50% relative
humidity at 40C
Pollution degree: 2
Storage Temperature: -20C to 60C, < 80% R.H. (with battery removed)
Altitude: Operating below 2000m
Temperature Coefficient: nominal 0.15 x (specified accuracy)/ C @(0C --
18C or 28C -- 40C), or otherwise specified
Sensing: True RMS
Safety: Double insulation per IEC/EN61010-1 2nd Ed.,
UL61010-1 2nd Ed. & CAN/CSA C22.2 No.
61010.1-0.92 to CAT IV 1000V AC & DC
Transient Protection: 12kV (1.2/50s surge)
Overload Protections:
Clamp-on jaws: 2000A rms continuous
“ + “ & COM Terminals (all other functions): 1000V rms
E.M.C.: Meets EN61326-1:2006 (EN55022, EN61000-3-2,
EN61000-3-3, EN61000-4-2, EN61000-4-3,
EN61000-4-4, , EN61000-4-5, EN61000-4-6,
EN61000-4-8, EN61000-4-11)
In an RF field of 3V/m:
Capacitance function is not specified
Other function ranges: Total Accuracy = Specified Accuracy + 200 digits
Performance above 3V/m is not specified
Power Supply: 1.5V AA Size (IEC LR6) battery X 2
Power Consumption: Typical 14mA for Current functions, and 5.2mA for
others
Low Battery: Below approx. 2.4V
APO Timing: Idle for 34 minutes
APO Consumption: 10A typical
Dimension: L264mm X W97mm X H43mm
Weight: 608 gm
Jaw opening & Conductor diameter: 55mm max
Accessories: Test leads (pair), user's manual, banana plug K-
type thermocouple x 1
Optional purchase accessories: USB interface kit AMD 9250; AMD9024 banana
plug to type-K socket plug adaptor
Special Features: AutoCheckTM V&; VFD-V & VFD-Hz; Backlighted
LCD; 5ms CREST-MAX Capture mode (Peak
Hold); Auto-ranging Relative-Zero mode; Display
Hold; EF-Detection (NCV); Optional Interface
capabilities with PC computers

MD 9250 Clamp Meter Series Specifications
17
Electrical Specifications
Accuracy is (% reading digits + number of digits) or otherwise specified, at 23C 5C
& less than 75% relative humidity.
True RMS voltage accuracies are specified from 5 % to 100 % of range or otherwise
specified. Maximum Crest Factor < 1.4 : 1 at full scale & < 2.8 : 1 at half scale, and with
frequency components within the specified frequency bandwidth for non-sinusoidal
waveforms.
DC Voltage
RANGE
Accuracy
6.000V, 60.00V,
600.0V & 1000V
0.5%+5d
Input Impedance: 10M, 50 pF nominal
AutoCheckTM_ DCV
RANGE
Accuracy
6.000V, 60.00V,
600.0V & 1000V
1.3% + 5d
AutoCheckTM Lo-Z DCV Threshold:
> +1.5VDC & < -1.5VDC nominal
AutoCheckTM Lo-Z DCV Input Impedance:
Initially approx. 2.5k, 600pF nominal; Impedance increases abruptly within a fraction
of a second as display voltage is above 50V (typical). Ended up impedances vs display
voltages typically are:
10k@100V
60k@300V
200k@600V
420k@1000V
AC Voltage
RANGE
Accuracy
50Hz ~ 400Hz
6.000V, 60.00V,
600.0V & 1000V
1.2% + 5d
Input Impedance: 10M, 50 pF nominal

MD 9250 Clamp Meter Series Specifications
18
AC+DC Voltage
RANGE
Accuracy
DC, 50Hz ~ 400Hz
6.000V, 60.00V,
600.0V & 1000V
1.4% + 7d
Input Impedance: 10M, 50 pF nominal
AutoCheck_ACV
RANGE
Accuracy1)
50Hz ~ 60Hz
6.000V, 60.00V,
600.0V & 1000V
1.5%+5d
AutoCheckTM Lo-Z ACV Threshold:
> 1.5V(50/60Hz) nominal
AutoCheckTM Lo-Z ACV Input Impedance:
Initially approx. 2.5k, 600pF nominal; Impedance increases abruptly within a fraction
of a second as display voltage is above 50V (typical). Ended up impedances vs display
voltages typically are:
10k@100V
60k@300V
200k@600V
420k@1000V
VFD_ACV (with Low Pass Filter )
RANGE
Accuracy1)
10Hz ~ 20Hz
6.000V, 60.00V,
600.0V & 1000V
4%+80d
20Hz ~ 200Hz
6.000V, 60.00V,
600.0V & 1000V
2%+60d
200Hz - 400Hz2)
6.000V, 60.00V,
600.0V & 1000V
7%+80d
1)Not specified for fundamental frequency > 400Hz
2)Accuracy linearly decreases from 2% + 50d @ 200Hz to 7% + 80d @ 400Hz
CREST-MAX Capture Mode
Accuracy: Specified accuracy plus 250 digits for changes > 5ms in duration
Ohm & AutoCheckTM_Ohm 1)
RANGE
Accuracy
600.0, 6.000K, 60.00K
0.5%+5d
600.0K
0.8%+5d
6.000M
1.2%+5d
40.00M
2.3%+5d
Open Circuit Voltage: 0.45VDC typical

MD 9250 Clamp Meter Series Specifications
19
1)AutoCheckTM Ohm Threshold:
< 10.00Mnominal
Audible Continuity Tester
Audible Threshold: Between 10and 200
Response time: 32ms approx.
Capacitance
RANGE
Accuracy1)
60.00nF, 600.0nF, 6.000F
2.0%+5d
60.00F,600.0uF
3.5%+5d2)
2000F
4.0%+5d2)
1)Accuracies with film capacitor or better
2)Temperature Coefficient: 0.25 x (specified accuracy)/ C @(0C -- 18C or 28C --
40C)
Diode Tester
RANGE
Accuracy
1.000V
1.0% + 3d
Test Current: 0.56mA typically
Open Circuit Voltage: < 1.8VDC typically
DCA Current (Clamp on)
RANGE
Accuracy1) 2)
200.0A
2.0%+5d
0~500A
2.0%+5d
500~2000A
3.0%+5d
1)Induced error from adjacent current-carrying conductor: <0.1A/A
2)Specified with Relative Zero mode applied to offset the non-zero residual readings,
if any
ACA Current (Clamp on)
RANGE
Accuracy1)
50Hz ~ 60Hz
200.0A
2.0%+5d
0~500A
2.5%+5d
500~2000A
3.0%+5d
40Hz ~ 50Hz & 60Hz ~ 400Hz
200.0A
2.0%+5d
0~500A
3%+5d
500~1000A
3.5%+5d
1000~2000A
indicative
True RMS Crest Factor :
< 1.4 : 1 at full scale & < 2.8: 1 at half scale
1)Induced error from adjacent current-carrying conductor: < 0.1A/A

MD 9250 Clamp Meter Series Specifications
20
DC+ACA Current (Clamp on)
RANGE
Accuracy1) 2)
DC, 50Hz ~ 60Hz
200.0A, 2000A
3.0%+8d
40Hz ~ 50Hz & 60Hz ~ 400Hz
200.0A
3.5%+8d
0~1000A
3.5%+8d
1000~2000A
indicative
True RMS Crest Factor:
< 1.4 : 1 at full scale & < 2.8 : 1 at half scale
1)Induced error from adjacent current-carrying conductor: < 0.1A/A
2)Specified with Relative Zero mode applied to offset the non-zero residual readings,
if any
Temperature
RANGE
Accuracy
-50 oC ~ 1000 oC
0.3% +4d
-58 oF ~ 1832 oF
0.3% + 6d
K-type thermocouple range & accuracy not included
Hz Line Level Frequency
Function
Sensitivity
(Sine RMS)
Range
6V
2V
40Hz ~ 1999Hz
60V
20V
40Hz ~ 1999Hz
600V
100V
40Hz ~ 1999Hz
1000V
600V
40Hz ~ 1999Hz
200A
10A
20Hz ~ 400Hz
2000A
40A
20Hz ~ 400Hz
VFD 6V1)
1V~2V
10Hz ~ 400Hz
VFD 60V1)
6~20V
10Hz ~ 400Hz
VFD 600V1)
60V~200V
10Hz ~ 400Hz
Accuracy: 0.1%+4d
1)VFD sensitivity linearly decreases from 10% F.S. @ 200Hz to 40% F.S. @ 400Hz
Non-Contact EF-Detection
Typical Voltage
Bar-Graph Indication
20V (TOLERANCE: 10V ~ 36V)
-
55V (TOLERANCE: 23V ~ 85V)
- - -