Loop impedance · Internal grid impedance · Solar park O&M

Sonel MZC-340-PV loop impedance tester

The Sonel MZC-340-PV is a loop impedance tester for applications in grids up to 900 V AC. In solar parks, it is particularly relevant for measurements on the AC side between inverter and transformer.

For O&M teams, the measured value alone is not enough. What matters is how safely technicians can set up the measurement, how results are documented and how the measurement fits into the overall testing and reporting process.

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for loop impedance and internal grid impedance up to 900 V AC
four-wire measurement from 7.2 mΩ to 1999 mΩ
for utility-scale O&M in the context of measurement process, data and reporting

Description

What is the MZC-340-PV suitable for?

Solar parks and large PV plants use inverters with high DC and AC voltages. The MZC-340-PV is designed for applications where loop impedance and internal grid impedance have to be measured between inverter and transformer.

The instrument enables measurements at grid voltages up to a maximum of 900 V AC. The maximum test current is 305 A. Loop impedance is measured as a four-wire measurement in the range from 7.2 mΩ to 1999 mΩ.

Beyond the device function itself, O&M teams need to define how the measurement setup is prepared safely, how results are interpreted and how the data is documented in a traceable way afterwards.

Measurement functions

What can be measured with the MZC-340-PV

The following overview summarizes the key measurement functions from the available MZC-340-PV documentation.

Loop impedance	Four-wire measurement
Prospective short-circuit current	Calculation based on loop impedance
Voltage measurement	AC grid voltage up to 900 V
Frequency measurement	45 Hz to 65 Hz
Touch voltage	0 V to 100 V
Touch shock voltage	possible with a special measuring probe

Measurement solution instead of standalone device

Do not only check whether the instrument technically fits

For loop impedance measurements in solar parks, setup, accessories, safety concept, documentation and reporting determine whether the device can be used productively in everyday O&M work.

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Technical data

Important technical data at a glance

The key technical data show where the Sonel MZC-340-PV is especially relevant in solar park O&M: precise loop impedance measurement on the AC side, high grid voltages up to 900 V, four-wire measurement, high test currents and classification according to EN IEC 61557-3.

Model	Sonel MZC-340-PV
Index	WMGBMZC340PV
Device category	Loop impedance tester
AC grid voltage	0 V to 900 V
Frequency	45 Hz to 65 Hz, resolution 0.1 Hz
Loop impedance Z_S	7.2 mΩ to 1999 mΩ, four-wire measurement, U_N = 200 V to 900 V
Resolution Z_S	0.1 mΩ in the range 0.0 mΩ to 199.9 mΩ; 1 mΩ in the range 200 mΩ to 1999 mΩ
Accuracy Z_S	±(2 % of reading + 2 mΩ)
Max. test current	305 A; depending on grid voltage, including 220 A at 800 V, 190 A at 690 V, 280 A at 500 V, 220 A at 400 V, 130 A at 230 V
Prospective short-circuit current	including up to 111.1 kA at U_N = 800 V, depending on measuring range
Touch voltage	0 V to 100 V, resolution 1 V, accuracy ±(10 % of reading + 2 digits)
Measurement method standard	EN IEC 61557-3, loop resistance

Standards & safety

Standards, guidelines and measurement context

The Sonel MZC-340-PV is designed for loop impedance measurements in low-voltage grids and is therefore particularly relevant for AC-side testing in solar parks. What matters is not only the device class, but whether measurement method, safety requirements and documentation fit the specific test task.

Loop impedance

The measurement classification is based on EN IEC 61557-3 for devices used to measure loop resistance in low-voltage grids.

Device safety & EMC

In practical use, safety and EMC requirements are relevant in addition to the measurement method, including the IEC 61010 and IEC 61326 standards families for electrical measuring instruments.

Practice in the solar park

In O&M operation, every measurement should be preceded by a check of whether grid type, voltage level, measurement category, test leads and work clearance match the specific AC-side use case.

Downloads

Documents for the MZC-340-PV

Here you find the most important manufacturer documents for the Sonel MZC-340-PV: instruction manual, datasheet and declaration of conformity. These documents support technical classification, measurement preparation, safe use and internal documentation in the O&M process.

PDF Instruction manual Manual for operation, settings and measurement procedures PDF Datasheet Technical data, measuring ranges and specifications PDF Declaration of conformity Manufacturer documentation on conformity

Included set

What is included in the standard set

The actual scope of delivery may vary depending on offer and configuration. The following list is based on the available MZC-340-PV product data set.

Two-core test lead U1/I1

3 m, 10/25 A, CAT IV 1000 V

Two-core test lead U2/I2

3 m, 10/25 A, CAT IV 1000 V

Test lead

1.8 m, black, 5 kV

Kelvin probes

2x Kelvin probe, 1 kV, CAT IV 1000 V

Test probe

black, 11 kV

Kelvin clips

2x Kelvin clip, 1 kV, 25 A, CAT IV 1000 V

M-6 accessory bag

Transport and organization of accessories

Z-19 battery charger

Charger for instrument use

Mains cable

Cable for 230 V power supply with IEC-C7 plug

USB cable

for data transfer and device integration

Factory calibration certificate

Manufacturer documentation for calibration

Accessories & software

Additions for practical use

For productive O&M use, not only the tester and leads matter, but also data transfer, test report creation and the availability of accessories in the field.

Control device / tablet

Optional control device for practical operation and field use with suitable measurement and work procedures.

Sonel Reader

Free software for data transfer from the measuring instrument to the PC.

Sonel Reports Plus

Software for creating test documentation and structured reports.

Context

When the MZC-340-PV can fit well - and when it should be checked first

The decision for a loop impedance tester should always be assessed in the specific grid, plant and O&M context.

Can fit well if …

loop impedance or internal grid impedance has to be measured on the AC side of solar parks.
measurements at grid voltages above classic low-voltage applications are relevant.
a repeatable measurement process between inverter and transformer has to be established.
technicians need to document measured values and short-circuit current in a traceable way.

Check first if …

it is unclear which measuring points in the solar park are actually accessible.
the accessories or safe measurement procedure have not yet been defined.
measurement values have to be transferred into standardized reports later.
several technicians or sites should work with a consistent procedure.

Next steps

From tester to safe measurement process

The MZC-340-PV can be part of a broader measurement concept. What matters is that team, measurement points, accessories, data structure and reporting are defined cleanly beforehand.

Assessment

For teams that want to clarify before procurement or introduction whether the instrument and planned measurement process fit the use case.

Rollout

For companies that want to introduce instrument, accessories, measurement workflow, data structure and reporting as a repeatable work process.

Critical Support

For acute questions in the field, unclear measurement results or short-term technical interpretation of measurement data and reports.

FAQ

Frequently asked questions about the MZC-340-PV

The following questions help to classify when the Sonel MZC-340-PV is useful in solar park O&M and which points should be considered for measurement setup, safety, data transfer and reporting.

Is the MZC-340-PV specifically suitable for solar parks?

Yes. The Sonel MZC-340-PV is particularly relevant for loop impedance measurements on the AC side of PV plants. With an operating range up to 900 V AC, the instrument fits measurement tasks that may occur around inverters, AC collection points or transformer stations in utility-scale solar parks.

The specific use must still always be checked against grid structure, voltage level, measuring point, measurement category, safety concept and local work clearance process.

What is different from classic loop impedance measurement?

Solar parks can have different boundary conditions than classic building installations: higher AC voltages, longer cable runs, larger feed-in power, different grid types and measurement points around inverters or transformer stations.

Therefore, it is not enough to look only at the measured value. Instrument, test leads, measurement setup, grid type, safety clearance and documentation must fit the specific O&M use case.

Which measurement tasks does the MZC-340-PV cover in O&M?

The focus is on loop impedance, internal grid impedance, prospective short-circuit current and touch voltage on the AC side. These measurements can help to assess protective measures, grid conditions and technical abnormalities in the solar park.

It is important not to view the measurement results in isolation, but in connection with plant structure, protection concept, documentation and the specific test assignment.

Can the MZC-340-PV measure touch voltage?

Yes. The instrument can measure touch voltage up to 100 V. Depending on the measurement task, special accessories or a suitable measuring probe may also be required.

In O&M operation, it should be clarified in advance at which measurement points touch voltage is relevant and how the results should be documented and assessed.

Which software is relevant for data transfer and reports?

Sonel Reader and Sonel Reports Plus can be relevant for data transfer and documentation. What matters is that measurement data is not only transferred, but assigned clearly to the correct project, measurement point and test task.

Therefore, in addition to device operation, sunparq also considers data structure, export, report logic and storage so that the measurement results can later be used traceably in the O&M process.

Is the MZC-340-PV a replacement for a PV tester up to 1500 V?

No. The MZC-340-PV complements PV testers, but does not replace them. PV testers up to 1500 V are typically used for DC-side measurement tasks such as open-circuit voltage, short-circuit current, insulation measurement or I-V curve measurement.

The MZC-340-PV, by contrast, is designed for AC-side loop impedance and internal grid impedance measurements. In a complete solar park measurement process, both device types can take on different roles.

How does sunparq support implementation?

sunparq can support the use of the MZC-340-PV through Assessment, Rollout, Operational Readiness or Critical Support. The focus is not only on device operation, but on the entire measurement process.

This includes classifying the measurement task, selecting accessories, preparing the measurement workflow, data structure, reporting and technical assessment of results in the specific solar park O&M context.

Next step

In 15 minutes, we clarify whether and how we can help

We first review your target setup, team structure, PV testers, reporting and support needs - then we decide together whether Assessment, Rollout or Operational Readiness is the right fit.