Sonel MZC-304 User manual

USER MANUAL
FAULT LOOP IMPEDANCE METER
MZC-304
SONEL S.A.
Wokulskiego 11
58-100 Świdnica
Version 2.04 03.04.2019

MZC-304 –USER MANUAL
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CONTENTS
1Safety............................................................................................................................ 3
2Measurements.............................................................................................................. 4
2.1 Turning the meter on and off, display backlight .......................................................4
2.2 Selection of general measurement parameters .......................................................4
2.3 Remembering the last measurement result .............................................................5
2.4 Measurement of alternating voltage.........................................................................5
2.5 Measurement of voltage and frequency...................................................................6
2.6 Checking correctness of PE (protective earth) connections ....................................6
2.7 Measurement of fault loop parameters .................................................................... 7
2.7.1 Cable length selection.......................................................................................................7
2.7.2 Prospective short-circuit current........................................................................................8
2.7.3 Measurement of fault loop parameters in the L-N and L-L circuits.....................................8
2.7.4 Measurement of fault loop parameters in the L-PE circuit...............................................11
2.7.5 Measurement of short circuit loop impedance in L-PE circuit protected by a residual
current device (RCD) ......................................................................................................13
2.8 Measurement of resistance to earth....................................................................... 14
2.9 Low-voltage resistance measurement ...................................................................15
2.9.1 Measurement of continuity of protective conductors and equipotential bondings with  200 mA
current.............................................................................................................................15
2.9.2 Low-current measurement of resistance .........................................................................16
2.9.3 Compensation of test leads resistance - autozeroing......................................................17
3Memory of measurement result data....................................................................... 18
3.1 Storing the measurement result data in the memory .............................................19
3.2 Changing the cell and bank number ......................................................................21
3.3 Viewing memory data............................................................................................. 21
3.4 Deleting memory data............................................................................................ 22
3.4.1 Deleting bank data..........................................................................................................22
3.4.2 Deleting the whole memory.............................................................................................23
3.5 Communication with a computer............................................................................24
3.5.1 Computer connection accessories ..................................................................................24
3.5.2 Data transmission with Bluetooth 4.2 module..................................................................24
3.5.3 Data transmission with OR-1 module..............................................................................26
4Troubleshooting ........................................................................................................ 27
5Power supply of the meter........................................................................................ 28
5.1 Monitoring of the power supply voltage..................................................................28
5.2 Replacement of batteries....................................................................................... 28
5.3 General rules of using the Nickel Metal Hydride (Ni-MH) batteries...........................29
6Cleaning and maintenance ....................................................................................... 29
7Storage ....................................................................................................................... 30
8Dismantling and disposal ......................................................................................... 30
9Technical specifications ........................................................................................... 30
9.1 Basic data .............................................................................................................. 30
9.2 Additional information ............................................................................................ 33
9.2.1 Additional uncertainty according to IEC 61557-3 (Z) .......................................................33
9.2.2 Additional uncertainty according to IEC 61557-4 (R ±200 mA)........................................33
10 Equipment.................................................................................................................. 34
10.1 Standard equipment...............................................................................................34
10.2 Optional accessories..............................................................................................34
11 Manufacturer.............................................................................................................. 35
12 Laboratory services................................................................................................... 36

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1 Safety
The MZC-304 meter is designed for testing the protection against electric shock in the mains sys-
tems. The meter is used to make measurements which results determine the electrical installation
safety level. Consequently, in order to ensure safe operation and correct measurement results, ob-
serve the following recommendations:
Before you proceed to operate the meter, acquaint yourself thoroughly with the present manual
and observe the safety regulations and recommendations of the manufacturer.
Any application that differs from those specified in the present manual may cause damage of the
instrument and a serious hazard to its user.
The MZC-304 meters must be operated solely by appropriately qualified personnel with relevant
certificates to perform measurements of electric installation. Operation of the instrument by unau-
thorized personnel may result in damage to the device and constitute a hazard to the user.
Using this manual does not exclude the need to comply with occupational health and safety regu-
lations and with other relevant fire regulations required during the performance of a particular type
of work. Before starting the work with the device in special environments, e.g. potentially fire-
risk/explosive environment, it is necessary to consult it with the person responsible for health and
safety.
It is unacceptable to operate the following:
a damaged meter which is completely or partially out of order,
leads with damaged insulation,
a meter which ahs been stored to long in unsuitable conditions (for example is wet). When the
meter is transferred from cold environment to warm and humid one, do not make measure-
ments until the meter warms up to the ambient temperature (about 30 minutes).
Remember that the message on the display means that the power supply voltage is too low
and indicates the need to replace/ charge the batteries. The measurements performed with the
meter with insufficient supply voltage have additional measuring errors which are impossible to be
evaluated by the user and cannot be the basis to determine the correct protection of the tested in-
stallation.
Do not leave the discharged batteries in the meter as they can leak and damage the instrument.
Before starting the measurement, check if the leads are connected to correct measuring termi-
nals.
Never use the meters with open or only partially closed battery compartment cover and use only
the power supplies specified in this manual.
Repairs may be performed solely by an authorized service outlet.
NOTE
Use only standard and optional accessories intended for a given instrument which are
listed in the “Equipment” section. Using other accessories may cause damage of the
measuring terminal and additional measuring errors.
Note:
An attempt to install drivers in 64-bit Windows 8 may result in displaying "Installation
failed" message.
Cause: Windows 8 by default blocks drivers without a digital signature.
Solution: Disable the driver signature enforcement in Windows.

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Note:
Due to continuous development of the meter software, the display view for some functions
may be a bit different from the view shown in this manual.
2 Measurements
WARNING:
During the fault loop measurements, the earthed parts and parts accessible in the electri-
cal installation being tested must not be touched.
WARNING:
During a measurement, switching of the range switch is forbidden because it may damage
the meter and pose a threat to the user.
2.1 Turning the meter on and off, display backlight
Briefly press the button to turn on the meter. Press it for a longer time to turn it off (
is displayed). Press briefly the button during meter operation to turn on/off the display and
keypad backlight.
2.2 Selection of general measurement parameters
Keeping the SET/SEL button de-
pressed, turn on the meter and wait for
the parameter selection screen.
Use the buttons to go to the next param-
eter.
Use the buttons to change the parameter
value. The value or symbol to be changed is
flashing.
The symbol indicates an active parameter,
the - symbol indicates an inactive one.

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Set the parameters according to the following algorithm:
Parameter
Mains
voltage
Voltage for
calculating
IK: rated/
measured
Auto-
OFF
Change PIN
Supply
source se-
lection
Buzzer
Software
updating
Symbol(s)
?
Press ENTER to validate the changes and go to the
measurement function,
or
...press ESC to go the measurement function with-
out validating the changes.
Note:
- Before the first measurements, select the mains rated voltage Un(220/380V, 230/400V or 240/415V)
used in in the area where measurements are performed. This voltage value is used for calculating the
values of prospective short-circuit current, if this option was chosen from the main menu.
- The symbol means that no auto-off time has been set.
- PIN settings - see section 3.5.2 Data Transmission.
- For software update proceed according to point 3.5.1. New software may be downloaded from
www.sonel.pl.
2.3 Remembering the last measurement result
Result of the latest measurement is remembered by the meter until a next measurement is
started, or measurement settings are changed, or the measuring function is changed by means of the
rotary switch, or the meter is switched off. When you go to the output screen of a given function with
the ESC button, you can recall this result by pressing ENTER. Similarly, you can view the latest
measurement result after turning off and then turning on the meter.
2.4 Measurement of alternating voltage
The meter measures and displays alternating mains voltage in all measuring functions except
R. This voltage is measured for the frequencies within the range of 45..65 Hz. The test leads should
be connected as for a given measuring function.

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2.5 Measurement of voltage and frequency
Set the rotary switch in the U,f
position.
Read the result of
measurement: the
voltage on the sec-
ondary display field,
the frequency on the
principal.
2.6 Checking correctness of PE (protective earth) connections
or
PE
Note:
WARNING:
When a dangerous voltage is detected on PE conductor, measurements must be immedi-
ately stopped and a fault in the installation must be removed.
- The person making a measurement must ensure that he/she is standing on a non-insulated floor
during the measurement; otherwise the result of the measurement may be incorrect.
- The threshold value, which triggers the signal of exceeded allowable voltage on PE conduit, is ap-
proximately 50 V.
When the meter is connected as in the the dra-
wing, touch the contact electrode with your finger
and wait for about 1 second. When voltage if fo-
und on PE, the meter displays the symbol (er-
ror in the installation; PE connected to the phase
conductor) and generates a continuous audio si-
gnal. This option is available for the ZL-PE mea-
surements.

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2.7 Measurement of fault loop parameters
If there are residual current devices in the tested network, they should be bypassed by
bridging for the period of impedance measurement. However, it should be remembered
that the tested circuit is modified in this way and the obtained results may slightly differ
from the actual results.
Each time after completion of measurements, modifications introduced to the installation
for the period of measurements should be removed and operation of the residual current
device should be checked.
The above remark does not apply to measurements of fault loop impedance with the use of
the ZL-PE RCD function
Measurements of fault loop impedance performed downstream of inverters are ineffective
and their results are unreliable. This is due to the instability of internal impedance in in-
verter circuits during its operation. The measurements of fault loop impedance should not
be performed directly downstream of inverters.
2.7.1 Cable length selection
Turn the rotary switch to one of the loop imped-
ance measurement ranges.
Set the parameters according to the following algorithm, and according to
the rules described in general parameters setting.
NOTE: The WS-07, WS-05 and WS-01 cables are detected by the meter
and it is then impossible to select the cable length (the symbol is dis-
played for WS-05 and WS-01 and symbol for WS-07). Using cables ter-
minated with banana plugs, before starting to measure, select the appropri-
ate length of the phase conductor, compatible with the length of cable used
for measurement.
Note:
Using cables from known manufacturers and selecting the correct length guarantees the
declared measurement accuracy.

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2.7.2 Prospective short-circuit current
The meter always measures impedance. The short-circuit current is calculated according to the
following formula:
S
n
kZ
U
I
where: Un- mains rated voltage, ZS- measured impedance.
On the basis of Unrated voltage selected (section 2.1), the meter automatically recognizes the
measurement at phase-to-neutral or phase-to-phase voltage and takes it into account in the calcula-
tions.
If the voltage of the tested mains is outside the tolerance range, the meter will not be able to de-
termine a proper rated voltage for the short-circuit current calculation. In such a case, horizontal
dashes will be displayed instead a short-circuit current value. The following diagram shows voltage
ranges for which short-circuit current value is calculated.
230 400 440 U [V]
Voltage ranges for which the
short-circuit current is calculated
U ,
L-N
Voltage range for which the impedance is measured
207 253 360
220 380 418
198 242 342
373 415 440 216 240 264
440 U [V]
U [V]
U =220V
n
U =230V
n
U =240V
n
Voltage ranges U , for which the
short-circuit current is calculated
L.-L
2.7.3 Measurement of fault loop parameters in the L-N and L-L circuits
Turn on the meter.
Turn the rotary switch
to the ZL-L ZL-N position.
Depending on needs, select cable length according to section 2.7.1.

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or
N L N L
a) b)
Connect test
leads according
to the drawing
a) for meas-
urement in the
L-N circuit
or
b) for meas-
urement in the
L-L circuit
The meter is ready for
measurement.
Phase conductor
length or the or
symbol.
UL-N or UL-L voltage
Make the measurement by pressing the
START button.
Read the main meas-
urement result: fault
loop impedance ZSand
the mains voltage at the
time of measurement.
To read additional results, press the button.

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IK
short-circuit
current
R
fault loop
resistance
XL
fault loop
reactance
Note:
- Enter the result into memory (see sections 3.1 and 3.2) or press ESCto return to go to the voltage
measurement.
- When many measurements are made at short time intervals, the meter may emit a large amount of
heat. As a result of this, the enclosure of the device may become hot. This is normal and the meter is
equipped with the protection against excessive temperature.
- Minimum interval between successive measurements is 5 seconds. This is controlled by the meter
which displays the message informing that the measurement can be made.

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Additional information displayed by the meter
The meter is ready for measurement.
Voltage on terminals L and N is outside the measurable range.
Voltage on terminals L and PE is outside the measurable range.
Error during the measurement.
Error during the measurement –voltage dip after the measure-
ment.
Short circuit malfunction.
Conductor N is not connected.
Huge noise in the system during the measurement. The meas-
urement result may be affected by a large, unspecified error.
The temperature inside the meter has risen above the limit. The
measurement is blocked.
The L and N conductors have been switched (voltage between
terminals PE and N).
2.7.4 Measurement of fault loop parameters in the L-PE circuit
Turn on the meter.
Turn the rotary switch
to the ZL-PE position.
Depending on needs, select cable length according to section 2.7.1.
or
N LPE
Connect the test
leads according
to one of the
drawings.

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PE L
0
a)
b)
Checking effectiveness of protection against electric shock
of the enclosure in case of: a) TN b) TT.
The meter is ready
for measurement.
Phase conductor
length or the
symbol.
UL-PE voltage
Make measurement by pressing the START button.
Remaining issues connected with the measurements are the same as those described for meas-
urements in L-N circuit or L-L circuit.
Note:
Double lead measurement is possible when a test lead other that the lead with a mains socket is se-
lected.
Additional information displayed by the meter
Error messages and information - as for the L-N and L-L measurement.

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2.7.5 Measurement of short circuit loop impedance in L-PE circuit protected
by a residual current device (RCD)
The MZC-304 enables the fault loop impedance measurements without altering the mains pro-
tected by RCD's with the rated current of at least 30mA.
Turn on the meter.
Turn the rotary switch
to the ZL-PE
RCD
posi-
tion
Depending on needs, select the measurement parameters according
to section 2.7.1.
Connect the test leads according to one of the drawings.
Remaining issues connected with the measurements are the same as those described for meas-
urements of the L-PE circuit.
Note:
- Maximum measurement time is about 32 seconds. The measurement can be interrupted by press-
ing the ESC button.
- In the electrical installations with 30 mA RCD's the sum of leakage currents of the installation and
the test current may trip the RCD. If this happens, try to reduce the leakage current in the tested
mains (for example by disconnecting loads).

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Additional information displayed by the meter
Error messages and information - as for the L-N and L-L measurement.
2.8 Measurement of resistance to earth
The MPI-502 meter can be used for approximate measurements of resistance to earth. For this
purpose, the phase conductor is used as a secondary source of voltage which generates test current.
Connection diagram for the instrument for such measurement in the TN-C, TN-S and TT systems is
shown in the figure below.
L
PE
N(PEN)
Ru
Rr
During the measurement, check the connections of the measured earth electrode with the electri-
cal installation. For correct measurement, the tested earthing systm should be disconnected from the
electrical installation (N and PE conductors). If you want to measure the earth electrode, for instance
in the TN-C-S system and simultaneously use the phase of the same system as a secondary source
of current, disconnect the PE and N conductors from the measured earth electrode (see figure below).
Otherwise, the meter will measure an incorrect value (the test current will flow not only through the
measured earthing system).
L
PE
N
Ru
Rr
L1L1
L2
L3
PE
Disconnect
Note:
WARNING:
Disconnection of protective conductors is a serous life hazard for the staff performing the
measurements and also third parties. When the measurements are completed, the protec-
tive and neutral conductors MUST be reconnected.
- If it is not possible to disconnect the conductors, use an earth resistance meter from the MRU range.
- As the measurement result is the sum of impedances of the measured earth electrode, working
earthing system, source and phase conductor, it contains a positive error. However, if such error does
not exceed a limit value for the tested earthing system, it can be concluded that the earthing has been
made correctly and and there is no need for a more accurate measurement methods.

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2.9 Low-voltage resistance measurement
The meter can be damaged if connected to the voltage exceeding 500V.
2.9.1 Measurement of continuity of protective conductors and equipotential
bondings with 200 mAcurrent
Turn on the meter.
Turn the rotary switch
to the RCONT position.
The meter is ready
for measurement.
RX
N L
Connect test leads according to the draw-
ing.
Activate the measurement by pressing
the START button. The measurement
starts automatically for resistances lower
than 30
Read the measurement
result which is the arithme-
tic mean of two measure-
ments with 200mA current
flowing in opposite direc-
tions.

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Additional information displayed by the meter
The tested facility is live. The measurement is blocked.
Immediately disconnect the meter from the facility
(both conductors)!
Huge noise in the system during the measurement. The
measurement result may be affected by a large, unspeci-
fied error.
Measuring range is exceeded.
2.9.2 Low-current measurement of resistance
Turn on the meter.
Turn the rotary switch
to the Rxposition.
The meter is ready
for measurement.
RX
N L
Connect test leads according to the draw-
ing.
Read the measurement
result.

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Additional information displayed by the meter
The tested facility is live. The measurement is blocked.
Immediately disconnect the meter from the facility
(both conductors)!
Huge noise in the system during the measurement. The
measurement result may be affected by a large, unspeci-
fied error.
Measuring range is exceeded.
2.9.3 Compensation of test leads resistance - autozeroing
Turn on the meter.
Turn the rotary switch
to the RCONT or Rxposi-
tion
Set the autozeroing according to the following algorithm.
N L
Short the test leads.
Activate the autozeriong by pressing the
START button.
After completion of auto-
zeroing, the meter auto-
matically switches to the
"ready for measurement"
mode.

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Note:
- The message remains on the display after switching into one of the measurement func-
tions (resistance or continuity measurement) indicating that the measurement is made with compen-
sated least leads resistance.
- To remove the compensation, perform the above-mentioned activities but with open test leads.
When you enter the measurement screen, the message will not be displayed.
Additional information displayed by the meter
The tested facility is live. The measurement is blocked.
Immediately disconnect the meter from the facility
(both conductors)!
3 Memory of measurement result data
MZC-304 meters are equipped with the memory that can store 10000 single measurement re-
sults. The whole memory is divided into 10 memory banks, each of them containing 99 memory cells.
Thanks to dynamic memory allocation, each of the memory cells can contain different quantity of sin-
gle measurement results, depending on the needs. Optimal use of the memory can be ensured in this
way. Each measurement result can be stored in a memory cell marked with a selected number and in
a selected memory bank. Thanks to this, the user of the meter can, at his/her discretion, assign
memory cell numbers to individual measurement points and the memory bank numbers to individual
facilities. The user can also perform measurements in any sequence and repeat them without losing
other data.
Memory of measurement result data is not deleted when the meter is switched off. Thanks to
this, the data can be later read or sent to a computer. The number of a current memory cell or
memory bank is not changed either.
Note:
- Results of measurements performed for all measuring functions can be stored in one memory cell.
- After each entry of the measurement result to the cell, its number is automatically incremented. Set
the appropriate cell number to allow entering to a single cell of successive measurement results relat-
ing to a given measuring point (facility).
- Only the results of measurements activated by pressing the START button can be stored in the
memory (except autozeroing in low-voltage resistance measurement).
- It is recommended to delete the memory after reading the data or before performing a new series of
measurements that may be stored in the same memory cells as the previous ones.