ORMELABS MW1008P User manual

MW1008P, user manual
1
LCR meter MW1008P
User Manual
Copyright Ormelabs © 2010-2015
http://www.ormelabs.com

MW1008P, user manual
2
Table of contents
Page
General Information 5
Specifications 5
Terms and symbols 6
Prefixes of measurement units 7
Glossary 7
Generalities
Display 9
Keypad 10
Operation
Passive Components 14
Displayed parameters 15
Polarisation of electrochemical capacitors 17
Polarisation of coils 18
Measurement of batteries impedance 18
Components sorting 20
Serial and Parallel models 21
Displays types 21
Test conditions 23
Test frequencies 23
Impedances ranges 25
Open-short calibration 25
Connecting to a passive component 27
Connecting to a transformer 27
Pinout of DUT connector 28
Precision
Precision of resistances/impedances 29
Precision of inductances 30
Precision of capacitors 30
Theory of operation
Signal generator 29
Phase detector and analog/digital converter 30
Transformers 30
Calibration
Parameterizing the calibration 32
Calibration 33
Error messages 34
Diagnostics
Keyboard test 35
Buzzer test 36
i/v complex 36
A/D results 37

MW1008P, user manual
3
GENERAL INFORMATIONS
The MW1008P LCR Meter is a multi-frequency impedance measuring instrument capable of
measuring resistance, capacitance, inductance or transformer parameters from 1 mΩ to 100
MΩ. The MW1008P LCR meter has a basic accuracy of 0.2% and has 11 test frequencies plus
one user definable.
The LCR meter is controlled by a high-speed micro-controller with embedded logic that
controls the display and keypad, as well as setting measurement conditions and performing
calculations. Please refer to chapter “Operation” for more details about instrument operation.
SPECIFICATIONS:
Functions Auto, L+Q, C+D, R+Q, |Z|+, R+X, G+B, N+, N-1+,Vs+Vp,
M, L+AL, C+Vr (varactor option)
Equivalent circuit Series or parallel
Displayed parameters Value, Deviation, % deviation
Measurement display
L+Q: L 0,01 µH –99,99 H
Q 0,0001 –100
C+D: C 0,001 pF –99999 µF
D 0,0001 –10
R+Q: R 1 mΩ – 99,9 MΩ
Q 0,001 –100
|Z|+: |Z| 1 mΩ – 99,9 MΩ
-180,00° - +180,00°
R+X: R 1 mΩ – 99,9 MΩ
X 1 mΩ – 99,9 MΩ
G+B: G
B
N+: N 1 –9999
-180,00° - +180,00°
N-1+N-1 0.0001 –1
-180,00° - +180,00°
Vs+VpVs 230V/N or 115V/N, resolution 0,01V
Vp 115V or 230V
M M 0,01 µH –99,99 H
L+ALL 0,01 µH –99,99 H
ALL/N2(N user definable from 1 to 999)
with varactor adapter MW108 :
C+Vr C 0,001 pF –99999 µF
Vr 0,00-5,0V or 0,0 –28,0V
Test conditions :
Test frequencies 100 Hz, 120 Hz, 250 Hz, 500 Hz, 1 kHz, 2,5 kHz,
5 kHz, 7,8125 kHz, 12,5 kHz, 15,625 kHz, 25 kHz
Test voltage 0,5 Vrms ±10% (no load)

MW1008P, user manual
4
Measurement rate 2 measures per second (without averaging)
Ranging Auto or manual
Precision :
Conditions At least 15 minutes warm-up, 23 °C ± 5 °C
Base precision ±0,2 % (15Ω ≤ |Z| ≤ 300kΩ et f ≤ 1kHz)
See the accuracy section for detailed accuracy specifications
Various:
Fixture: 4 wires Kelvin on CB connector
Protection Protected up to 1 Joule of stored energy, 100 VDC max (for
charged capacitors)
Zeroing open/short circuit compensation
Compensation limits Short: R < 20 Ω |Z| < 50 Ω
Open: |Z| > 10 kΩ
Sorting Selection of tolerance (1,2,5,10 or 20%)
Averaging 2 to 8 measurements
General:
Operating Conditions
0 –50 °C, < 80% relative humidity
Power supply 7.5 –15V, 150 mAwith light, <100 mA without
Dimensions 6.125 in 1.5 in 3.875 in
(W x H x L)
Options:
MW108 Varactor adapter
MW10 Universal 4 wires Kelvin cable (mini-pincers)
MW-KELV Kelvin pincers cable
MW-SMT SMT cable
TERMS AND SYMBOLS
Parameter
Measurement
Unit symbol
Z
Complex impedance
ohm, 
Y
Admittance, 1/Z
Siemens, S
|Z|
Impedance module Z
ohm, 
Rs or ESR
Serial resistance,
Real part of impedance
ohm, 
X
Reactance,
imaginary part of impedance
ohm, 
G
Conductance,
Real part of admittance (Y)
siemens, S
B
Susceptance,
siemens, S

MW1008P, user manual
5
Imaginary part of admittance
Cs
Series capacitance
Farad, F
Cp
Parallel capacitance
Farad, F
Ls
Series Inductance
Henry, H
Lp
Parallel Inductance
Henry, H
Rp
Parallel Resistance
ohm, 
Q
Quality factor
none
D
Dissipation factor
none

Phase angle of |Z|
Degree
M
Mutual inductance
Henry, H
N
Turns ratio
none
Vp
Primary voltage
(transformer)
AC Volts, V
Vs
Secondary voltage
(transformer)
AC Volts, V
PREFIXES OF MEASUREMENT UNITS
Multiplier Scientific Ingineer Symbol
1000000 106 Mega M
1000 106 Kilo k
0,001 10-3 milli m
0,000001 10-6 micro µ
0,000000001 10-9 nano n
0,000000000001 10-12 pico p
GLOSSARY
Coil : A coil is made of several turns of insulated wire. The property of a coil
is to oppose itself to current variations and is characterized by its
inductance.
Capacity : The property of a capacitor. The capacity of a capacitor is expressed in
Farad (F).
Capacitor: Passive component made of two plates separated by a dielectric. The
property of a capacitor is to pass ac current while stopping dc current.
See also capacity and reactance.
Test frequency : The frequency in which the parameters of a component are measured.
The parameter values depends generally upon frequency.
Range: Impedance ranges that the instrument uses to perform measurements.
Impedance : Complex value characterizing a passive component. The impedance has
a real component (résistance) in series with an imaginary component
(reactance). A pure resistance doesn’t have reactance while pure coils
and capacitors doesn’t have resistance.

MW1008P, user manual
6
Inductance : A property of a coil by which an electromotive force is induced in it by
a variation of. The inductance of a coil is expressed in Henry (H).
Parameter : Electrical property measured. The main parameter is the most
important parameter of the component (capacity, inductance,
resistance). The secondary parameter has less importance and
characterizes component losses (quality factor, dissipation factor or
phase angle).
Accuracy : Difference between the measured value and the real value of a
component. Accuracy is expressed as a percentage for the main
parameter. The accuracy depends on the impedance and the test
frequency. Generally the secondary parameter accuracy is an absolute
value.
BasicAccuracy : The actual accuracy of the instruments depends of some parameters
like test frequency and impedance. The basic accuracy is the best-case
accuracy that can be expected, this means 1 kHz test frequency and
impedance between 10 and 100 k.
Source Resistance: Output resistance of the test signal generator. The DUT is connected to
the signal generator trough this resistor. The source Resistance depends
on the impedance range.
Resolution : Resolution is the smallest quantity that the instrument can display. Do
not confuse this value with accuracy.
Test Voltage : This is the rms value delivered from the instrument with no load for
creating a current through the device under test. The source resistor as
well as the actual DUT impedance imply that actual voltage across the
DUT is always below this value.

MW1008P, user manual
7
GENERALITIES
This chapter gives an overview of the MW1008P characteristics. For further information
please refer to the operation section.
DISPLAY
The two lines of the LCD show
measured values, selected
parameters, instrument status
and various messages. When
making normal measurements,
the major parameter (L, C, R,
|Z|, G) is shown on the top line
and the appropriate minor
parameter (Q, D, X, , B), is
shown on the bottom line. The
number of displayed digits and
the location of the decimal
point are automatically adjusted
according to the range and resolution. The symbol in front of the major parameter indicates
that the measurement is displayed as a relative or absolute deviation from a nominal value. A
dark arrow present in the top left of the display indicates the unit is in the Auto Parameter
mode. If a dark arrow is displayed in the bottom left of the LCD, the unit is in the Auto
Model mode. The Range is indicated at the top right of the display. The ‘A’ character behind
the Range number indicates that the instrument is in auto range mode. In Manual or Hold
ranging mode, this letter becomes a blinking “H” character. The selected test frequency is
displayed on the bottom right of the display. The word « USER » is displayed when the user
frequency is selected.

MW1008P, user manual
8
KEYPAD
The keypad is used to select
measurement conditions and to
enter values. All keys have two
functions, depending on
whether the key is pressed
momentarily or for two seconds
or longer.
L/C/R
This key selects the parameter being measured. Pressing the L/C/R key steps through the
major parameters to manually select the desired ([L+Q] or [L+AL], [C+D], [R+Q], [|Z|+],
[R+X], [G+B]). When this key is pressed for more than two seconds the instrument goes in
Auto Parameter mode. In this mode, the instrument will select the most appropriate parameter
pair according to the phase angle and the absolute impedance. This mode is indicated by the
presence of a dark arrow at the top left of the display. The different modes are described
below. The [L+AL] mode replaces the [L+Q] mode when the instrument is configured in AL
mode (see MENU key ).
n/Vs/M
This key selects the transformer measurement mode. Pressing this key steps through and
permits the selection of the desired function ( [N+], [1/N+], [Vs+Vp], [M+] ).
[N+] Turns ratio and phase angle
[1/N+] Reciprocal turns ratio and phase angle
[Vs+Vp] Secondary and Primary Voltage
[M+] Mutual Inductance and phase angle
Frequ.
The Freq. key selects one of the following test frequencies: 100 Hz, 120 Hz, 250 Hz, 500
Hz, 1 kHz, 2.5 kHz, 5 kHz, 7.8125 kHz, 12.5 kHz, 15.625 kHz and 25 kHz. The selected
frequency is indicated just above this key. When the user frequency is selected the word
USER is displayed. Pressing this key for longer than two seconds sets the LCR meter to use
the default parameters. The default frequency is 1KHz.
Hold/Range
The Hold/Range key selects the impedance range of measurement appropriate for the device under test.
Pressing this key holds the unit in its current measurement range. Repeated pressing of this key changes the
measurement impedance range (1 –6). Pressing this key for longer than two seconds returns the unit to auto-
ranging or normal mode. The range is displayed in the top right corner of the display. The ‘A’ character behind
the Range number
indicates that the instrument is in Auto Range mode. In Manual or Hold ranging mode, this
letter becomes a blinking “H” character. Pressing this key for two seconds or longer returns to
the Auto mode. See also chapter “Impedance ranges” page 24 for more details about
impedance ranges.

MW1008P, user manual
9
MODEL
TheMODEL key selects between a series or parallel equivalent circuit model for the device under test.
Pressing this key for two seconds or longer places the Model selection in Auto mode. In this case the instrument
selects the most appropriate model.
MENU
The MENU key allows access to a series of special configurable parameters. Pressing this key displays the
programmable options. The current state of each option is displayed on the first line of the LCD as that option is
selected. To move through the Menu, press the key under the forward or back arrows displayed on the LCD.
Menu
Default value
Purpose
Backlight
ON
The backlight can be set to ON or OFF. To turn the
backlight off, press the key under OFF.
Sound
ON
This option turns the audible alert function ON or OFF.
Averaging
ON
Set this feature to ON to compensate for random noise
that is apparent when measuring some components.
There are seven selectable step rates from 2 to 8. Each
step adds approximately .25 seconds to the sampling
refresh rate of the LCD display.
Numb.Avrg.
4
Number of measurements used for averaging.
Varactor
(varicap)
OFF
This option requires the MW108 Varactor Test Fixture
available from MW Instruments. Turning the Varactor
option to ON will place the LCR meter automatically in
the Varactor measurement mode upon saving and exiting
the Menu. To return to normal features, select the Menu
key and turn the Varactor feature OFF.
Usr f
(user frequency)
1.25 kHz
Set the user frequency from 100 Hz up to 25 kHz
Sorting
OFF
Use this feature to measure and sort like valued
components.
Turning the Sorting function ON will allow the user to set
the Tolerance between the value of the benchmark
component and like components to be measures. This
Tolerance is selected by pressing the NEXT key.
When the appropriate tolerance has been selected,
pressing the key under the left arrow enables the value of
the benchmark component to be entered by pressing the
‘Edit’ key. A cursor will appear under the first digit of the
value. Pressing the NEXT key will move the cursor to the
next digit. Pressing the ‘Change’ key will step the value of
the selected digit. When the desired value has been
entered, pressing the OK key will record this value.
Pressing the key under the right arrow will allow the user to set the

MW1008P, user manual
10
audible indication when a DUT meets the programmed parameters.
Default value for the Pass Beep is SHORT. Pressing the NEXT key
will change the value to LONG or NONE.
Pressing the key under the right arrow will present
the option of turning the backlight on or off when a
valid component is measured. The default value is
YES.
Pressing the Menu key now will allow you to save
the selected configuration and place the LCR meter
in the Relative measurement mode.
To turn the Sorting mode OFF, press the Menu key
and step backward or forward using the appropriate
arrow key until the Sorting option is displayed. Press
the key under OFF. Press the Menu key and save this
configuration.
AL measurement
OFF
Set this feature to ON to measure the AL value of an
unknown toroid core. Press the ‘forward arrow’ key to
enter the number of turns on the inductor. To enter the
number of turns, select EDIT. A cursor will be displayed
under the last digit on the LCD. Pressing the Change key
will step the value of the digit over the cursor. Pressing
the NEXT key will move the cursor to the far left
position. When the number of turns has been entered,
press the OK key. For accuracy, a minimum of 10 evenly
distributed turns on the core is recommended.
1. Pressing the Menu key and saving the current
configuration will place the LCR meter in L+AL
mode. The AL value will be displayed on the second line
of the display.
2. To return to normal measurements, press the Menu key
and step backward or forward using the appropriate arrow
key to the AL display option. Select OFF and press the
Menu key again. Save the current configuration.
DISP.
The DISP. key selects the manner that the value of a component will be displayed. If the
Sorting mode is disabled, pressing DISP.cycles through the following display types:
The value being measured
The deviation of the value from the current value –The D symbol next to the
measured parameter indicates that this function is active.

MW1008P, user manual
11
The percent of deviation from the current value - The D symbol next to the
measured parameter indicates that this function is active.
In Sorting Mode pressing DISP.cycles through the following display types:
The value being measured
The percent of deviation from a stored value - The D symbol next to the measured
parameter indicates that this function is active. In this mode, a PASS/FAIL message is
shown in the second line of the display according to the measured deviation and the
selected tolerance.
CAL
The CAL key allows access to open/short compensation. Pressing the CAL key displays the
zeroing options on the second line of the LCD –Open Short Exit. This option will zero the
LCR meter for the currently selected test frequency. Pressing the CAL key for more than two
seconds displays the zeroing options –OPEN SHORT Exit (note that the options are in all
capital letters). This option performs an open/short calibration through the entire range of test
frequencies.

MW1008P, user manual
12
OPERATING
POWER ON THE INSTRUMENT
The instrument can be powered either by a 9V battery or by an external power supply. In this
last case the power supply must be well filtered and its voltage must lie between 8 and 15V.
Consumption is 150mA approximately when the backlight is activated. In the case of battery
use a warning message is displayed when the voltage is below 7V. In this case the backlight is
automatically deactivated. Besides we advise you not to use lighting when the instrument is
supplied by battery, which makes it possible to divide by two the consumption of the
instrument. The battery replacement requires the opening of the battery compartment.
PASSIVE COMPONENTS
All non-ideal passive component (resistor,
capacitor or inductor) can be represented by
a real part (the resistance) in series or in
parallel with an imaginary part (reactance,
inductance if positive or capacitance if
negative). The impedance varies with
frequency. The series or parallel model are
equivalent at a given frequency and one can
goes from one model to the other one thanks
to the equations below.
Generally one model is more appropriate
than the other one in a given measurement
conditions, that is to say when the series or
parallel resistance represent a physical
property of the part.
Temperature can have a large impact on the
DUT impedance. Usually, capacitors have large
temperature coefficients except for ceramic
COG/NPO capacitors, which can exhibit only
a 0.003%/°C variation. Inductors, especially
those with non-air cores, may vary largely with
temperature. Ambient and DUT temperature
drifts may introduce error into the
measurement. Control ambient temperature
changes to reduce errors.

MW1008P, user manual
13
Capacitors :
Capacitors are measured in Farads. The basic construction of a capacitor is a dielectric material
between two electrodes. The many different types of capacitors available are classed according to
their dielectric types. The figure below shows the range of generic capacitance values for standard
types.
Acapacitor can be modeled as a pure
capacitor C with some parasitic elements,
see the figure below. RS is the actual series
resistance, comprised of the lead resistance
and the foil resistance. RS is generally very
low (a few mil). RD symbolizes the
dielectric loss. Its value changes with
frequency.
Dissipation factor, also known as loss
tangent, is the ratio of the series
resistance to the reactance. It indicates the capacitor quality. A low D indicates a nearly pure
capacitor. In order to achieve reliable measurement a short zero must be performed before any
ESR or D measurement because in this case the series resistor can be very small. Like most
everything else about capacitors, it changes with time, frequency, and temperature. ESR is a
single resistive value of a capacitor representing all real losses. It includes effects of the
capacitor's dielectric loss.
Electrolytic Capacitors:
The accurate measurement of electrolytic capacitors, particularly large value caps, can present
unique requirements. The MW1008 LCR meter applies an AC signal to the DUT. To test some
polarized components, such as electrolytic and tantalum capacitors, it may be preferable to use
only positive voltages. During normal operation, the AC current source swings negative 50%
of the time, which results in an inverse polarization of the capacitor under test. To prevent this
inverse polarization, a DC bias can be applied to prevent the voltage across the part from

MW1008P, user manual
14
becoming negative. The schematic for a simple test fixture to apply DC bias is provided at
Appendix 1.
Test frequency
Generally high value capacitors should be measured at lower test frequencies because the
impedance of the component will be very low. Low value capacitors should be measured at
higher frequencies.
Model
Measuring a capacitor in series or parallel mode can provide different results. The difference
can depend on the quality of the device, but primarily the capacitor's measured value most
closely represents its effective value when the more suitable equivalent circuit, series or
parallel, is used. To determine which model is best, consider the impedance magnitudes of the
capacitive reactance and Rs and Rp. Remember that reactance is inversely proportional to C,
so a small capacitor yields a large reactance. This implies that the effect of parallel resistance
(Rp) has a more significant effect than that of Rs. Since Rs has little significance in this case,
the parallel circuit model should be used to more closely represent the effective value. The
opposite is true when C has a large value. In this case the Series Resistance (Rs) is more
significant than Rp, thus the series circuit model becomes appropriate. Mid range values of C
require a more precise reactance-to-resistance comparison but the logic remains the same. The
rule of thumb for selecting the most appropriate model should be based on the impedance (|Z|)
of the capacitor:
Above approximately 10 kΩ - use parallel model
Below approximately l kΩ - use series model
Between these values - follow the manufacturer’s recommendation
Polarization of electrolytic capacitors
The MW1008 generates a sinusoidal signal of 0,5Veff centred on 0V. In certain cases it can be
necessary to polarize the capacitor to avoid the inversion of polarity across the capacitor. This
can be carried out simply by the circuit below (valid for impedance ranges 1 and 2).
Point LD corresponds to a virtual
ground, the capacitor is thus polarized
by external voltage VBIAS. This
voltage must be well filtered, one will
avoid the use of switching power
supply. For safety reasons one will
limit to 40V the maximum bias
voltage. The value of the C1 capacitor
will have to be such as its impedance is
low compared to the source resistance
(100 Ω for ranges 1 and 2). A value of
470 µF/63V will be sufficient in most
cases. The value of resistor R2 will be
of 390 Ω. A short zeroing should be
performed replacing the capacitor by a

MW1008P, user manual
15
short-circuit. One has to wait until displayed value is stabilized because of the circuit time-
constants. It is possible to use this circuit for low capacities, in this case it is necessary to
adapt R2 and C1 values to resistance source.
One will choose R2 so that its value is large compared to source resistance. C1 capacitor must
be large enough not to increase resistance source too much. One will take for R2 a value 4 or
5 times the source resistance, and for C1 a value such that its reactance is negligible compared
to source resistance for the 100 Hz frequency.
Inductors :
Inductors are measured in Henrys. An inductor is a device for storing energy in a magnetic
field (which is the opposite of a capacitor that is a device for storing energy in an electric
field). An inductor consists of wire wound around a core material. Air is the simplest core
material for inductors because it is constant, but for physical efficiency, magnetic materials
such as iron and ferrites are commonly used. The core material of the inductor, its length, and
number of turns directly affect the inductor's value.
Model of a real inductor
The series resistance, Rs, represents the resistive losses in the
windings. The parallel capacitance, Cp, is the equivalent
capacitive effect between the turns of the coil, and the
parallel resistance, Rp, is the sum of all losses in the core.
Open flux inductors are more sensitive to metallic materials
that are in close proximity, because such materials modify the
magnetic field. Toroidal inductors keep the flux inside the
core and are less sensitive to external conductors in close
proximity.
Inductor measurements can be made in either the series or parallel model. Where the inductance is
large, the reactance at a given frequency is relatively large so the parallel resistance becomes more
significant than any series resistance, therefore the parallel model should be used. For very large
inductance values a lower measurement frequency will yield better accuracy.
For low value inductors, the reactance becomes relatively low, so the series resistance is more
significant and the series model is the appropriate choice. For very small inductance values a
higher measurement frequency will yield better accuracy.
Range
Rsource
C1
R2
1
100 Ω
470 µF
390 Ω
2
100 Ω
470 µF
390 Ω
3
1 kΩ
47 µF
3,9 kΩ
4
10 kΩ
4,7µF
39 kΩ
5
100 kΩ
470 nF
390 kΩ
6
100 kΩ
470 nF
390 kΩ

MW1008P, user manual
16
All inductors have a maximum allowable current.Above this value the core saturates, the magnetic
field remains constant, and the inductance decreases to near zero. The maximum current is
dependent on the core material. A core material with high permeability gives a higher inductance
for the same number of turns as a core of low permeability. The drawback is that the core
saturates at a much lower current.
Futhermore the inductance varies according to the current level. If you measure the same inductor
with different instrument et the same frequency you can get different velue because the test
current is not the same for both instruments. It is possible to know the current flowing into the
inductor by measuring the resistance and the reactance of the inductor (R and X) and knowing
the source resistance. The source resistor varies according to the impedance range, its value is
100for ranges 1 and 2 for example.
i(rms) = Vs/√((Rs+R)2+X2)) with Vs = 0,5 Vrms (test voltage at no load).
Example: When measuring a coil one measures R = 2 and X = 43 . The range determined
by the instrument is range #2, which has a source resistance around 100 . The current value
flowing into the coil is:
i = 0,5/√(100+2)2+432) = 4,5 mA
Note: Inductors with a Q less than 1 will not be automaticallydetected. The LCR meter will default
to the Rs mode. Increasing the test frequency to where the inductor Q is greater than 1 will then
switch the major parameter to L. If, at the highest test frequency, the Q does not raise above 1,
manuallyselecting the Lmode will give the value of the inductor.
Inductors biasing
For measurement in range 1 or 2 one will take the following values :
R2 = R3 = 390 Ω/1W
C1 = C4 = 470 µF/160V

MW1008P, user manual
17
Bias current is Io= VBIAS/(R2+R3+r)
When using this circuit one will avoid to disconnect the inductor while a current is flowing
into it. VBIAS voltage should be decreased down to 0V in order to discharge the coil.
Opening the circuit can introduce a high voltage with high energy which can be dangerous
id the inductance or the current is high.
Resistors
The unit of measurement for resistance is the Ohm. Of the three basic circuit components,
resistors cause the fewest measurement problems. This is true because it is practical to measure
resistors by applying a dc signal or relatively low ac frequencies. Resistors are usually measured at
dc or low frequency ac where Ohm's Law gives the true value under the assumption that loss
factors are accounted for.
Model
For low values of resistors (below l kΩ) the choice usually becomes a low frequency
measurement in a series equivalent mode. Series because the reactive part most likely present in a
low value resistor is series inductance, which has no effect on the measurement of series R. For
high values of resistors (greater than several MΩ) the best choice is usually a low frequency
measurement in a parallel equivalent mode. Parallel because the reactive part most likely present
in a high value resistor is shunt capacitance, which has no effect on the measurement of parallel R.
Some high precision resistors are winding resistors, and the number of turns can be quite large for
high value resistors. In this case the series inductance can be quite large and measurement should
be done at low frequency to avoid errors caused by the inter-winding capacitance.
MEASUREMENT OF INTERNAL
RESISTANCE OF BATTERIES
The internal resistance of batteries can be measured
using circuit diagram shown here. The dc voltage is
isolated by capacitor C1 = 47µF. The internal
resistance will generally be measured at 1 kHz.
Before doing the measurement itself, it is necessary
to perform a short-circuit calibration by replacing
the battery with a short. The measurement is done
with no current. It is possible to connect shortly a
parallel resistor in order to drain some current. It is
only necessary then to do a little calculation to find
the actual internal resistance.

MW1008P, user manual
18
DISPLAYED PARAMETERS
L+Q Inductance and quality factor. Inductance is displayed in the first line of the
LCD. Units are H, mH ou µH. Q is the ratio of the imaginary part to the real
part an dis unit less. If Q is positive the component is inductive, capacitive in
the other case.
L+ALInductance and ALparameter. This values replace L+Q values when the AL
mode is selected. ALvalue is computed from the inductance and a given turn
number : AL= L/n2
C+D Capacity and dissipation factor. The capacity is displayed in the first line. The
capacity is either the series equivalent capacity (Cs) either the parallel
equivalent capacity (Cp). Units are pF, nF, µF or mF. D is the ratio of the real
part to the imaginary part. If the value displayed is negative the component is
inductive.
R+Q The resistance is either the series resistance (Rs or ESR) or the parallel
resistance (Rp) of the DUT. Units are , kor M.
|Z|+Absolute value and phase angle of the DUT. The absolute value is displayed in
the first line. The phase angle corresponds to the phase difference between the
current and the voltage. The instrument can measure phase angles between -
180.00° and +180.00°. A negative value indicates a capacitive component, a
positive value indicates an inductive component. High quality capacitors have
a phase angle closed to -90.00°. Resistors have a phase angle closed to 0°.
R+X Resistance et Reactance. Resistance
value is displayed in the first line,
the reactance in the second one.
These two values are respectively
the real part and the imaginary part
of the DUT. Units are , kor
M.
G+B Conductance and Susceptance.
These two values are respectively
the real and imaginary part of the
admittance Y = 1/Z. Units are S,
mS or µS.
AUTO Pressing more than 2s the L/C/R
key switches the instrument in
automatic mode. The instrument
determines the function the most
appropriate function according to
some criterias resumed in the
graphic below. When the
impedance is below 10 mthe
resistance function is selected.

MW1008P, user manual
19
MEASUREMENTS ON TRANSFORMERS
The MW1008P has a special function for measuring a transformer ratio between primary and
secondary windings, calculation of the equivalent secondary voltage for a supply transformer
and for measuring mutual inductance between primary and secondary windings.
The use of this function needs use of the 4 wires mini-pincers cable MW10. To use this mode
press key n/Vs/M .
The primary winding of the
transformaer shall be connected on
wires HD and LD (with a red
sleeve). The secondary winding
shall be connected to the 2 other
wires. The open/short calibration
must not be used. The primary
should be the winding with the
greatest number of turns. In case of
inversion, the instrument displays
an overflow message
“OVERFLOW” on ranges 2 and 3.
The instrument has 3 measurement ranges according to the
value of the turns ratio. The instrument places itself on the first
range allowing the widest measurement. In this range, the
primary voltage is attenuated by a higher source impedance,
which allows a wider secondary voltage measurement range.
The real range depends on several factors, such as transformer
primary impedance at the test frequency. During the test of an elevator transformer, one
should choose a frequency such that the primary impedance will be smaller than 100Ω in
order to get a measurement of N-1 up to 10. A smaller primary impedance allows to measure a
higher transformer ratio.
The following parameters are displayed by successive press on key n/Vs/M for the
characterisation of transformers.
N+Main parameter Ngives the turns ration
between primary and secondary windings.
Primary/secondary phase shift and test
frequency are displayed on second line.
N-1+While pressing twice key n/Vs/M the
instrument displays invert ratio n-1 = 1/n.
Vs+Vp Secondary and primary voltages. In the case of measurements on a
mains supply transformer, the instrument can calculate the secondary voltage
for a primary voltage of 230V or 115V starting
from measured value. Press key n/Vs/M until
parameters Vs and Vp appear.
HD
HS
LS
LD
PRIMAIRE
SECONDAIRE
Range
N-1
1
1 .. 10
2
0,1 .. 1
3
0 .. 0,1

MW1008P, user manual
20
Default primary voltage is 230V. To change to 115V, press key Menu .
The second line presents the 2 available options. Press
the key below 115 to select virtual primary voltage of
115V. The brackets will move around 115. Press key
EXIT to go back to parameters Vs/Vp and to display the
secondary voltage for 115V this time.
M+Mutual inductance and
primary/secondary phase shift The mutual inductance is obtained by measuring
primary current and secondary voltage of the transformer. This direct method
can lack of precision at highest frequencies because to parasitics elements of
the transformer. In case of capacity overflow, the message OVERFLOW is
displayed. If so, change impedance range by pressing key Hold/Range . It is
better to start with the lowest range and then increase range until getting a
result. The automatic mode should not be used for this function.
The calculation of the mutual inductance
can also be done by measuring the
inductance resulting from serializing 2
windings, by connecting them in the 2
possible configurations as shown on the
figure.
The M value is then :
M = (La-Lb)/4. The results from the 2
methods can be compared.
About mutual inductance :
When 2 winding are close to each other, the flux created by one can establish in the
second. The mutual inductance coefficient is the ratio of the flux produced by coil 1 in
coil 2 to the current that flows through coil 1.