The safety and reliability of electrical installations depend largely on the quality of the measurements performed. To ensure that an installation meets standard requirements and provides effective protection against electric shock, an appropriate meter is essential. Sonel offers a wide range of MPI series instruments that meet the needs of both installers and specialists involved in audits, periodic testing, or diagnostics of photovoltaic systems.

One series – many possibilities

The Sonel MPI series includes multi-function meters that combine several key measurement functions. Many of them enable basic installation testing: fault loop impedance measurement, RCD testing, insulation resistance measurement, and continuity of protective conductors. This is the basic set of measurements required by the IEC 60364 standard to confirm the correct operation of protection and shock protection.

All meters in the Sonel MPI family feature a robust design, high accuracy, and intuitive operation. Each model has a built-in measuring system resistant to interference and adapted to work in difficult field conditions, making them reliable tools both on construction sites and in daily service work.

Basic models – simplicity and reliability

For electricians performing regular inspections in single-family houses or small commercial buildings, the Sonel MPI-502F, Sonel MPI-506, and Sonel MPI-507 models are ideal solutions. These are compact instruments equipped with a segment display and a set of the most important measuring functions.

All three meters allow for fast fault loop measurement, testing of AC and A type RCDs, as well as continuity measurement of protective and equipotential bondings. The Sonel MPI-506 and Sonel MPI-507 models additionally offer insulation resistance measurement up to 500 V and a phase sequence detection function. The most advanced model in this group, the Sonel MPI-507, is also equipped with an earth resistance measurement function. Thanks to their simple menu and low weight, these devices perform well both in the daily work of mobile electricians and during periodic inspections of installations in residential buildings, schools, or offices.

 
Photo 1. Insulation resistance measurement using Sonel MPI-507 meter

Professional mid-range – versatility for professionals

More advanced solutions include the Sonel MPI-520, Sonel MPI-525, Sonel MPI-530, and Sonel MPI-530-IT models. They offer an extended range of functions – including insulation resistance measurement with voltage up to 1000 or 2500 V (MPI-525), phase sequence test, and in the case of the MPI-520, MPI-530, and MPI-530-IT models, also the possibility of earth resistance measurement. In the last two models, as many as four earth measurement methods are available. An additional advantage is the measurement of illuminance using an optional probe in the Sonel MPI-530 and Sonel MPI-530-IT.  Both mentioned models perform well in electrical installation measurements as well as during testing of grounding systems, lightning protection, or three-phase motor control. The MPI-530-IT model is the only one in its segment that also allows measurements in IT networks (with an isolated transformer neutral point).

Additionally, the Sonel MPI-520 meter has a built-in power consumption measurement function, and the MPI-530 and MPI-530-IT models are equipped with a single-phase power quality recorder, allowing for power quality analysis in simple systems.

Devices in this group feature graphical displays, which facilitate menu navigation, results presentation, and data interpretation. These instruments are popular among industrial electricians, contracting companies, and installation services. The user interface is based on classic membrane buttons and a rotary switch for function selection.

 
Photo 2. Measurements using Sonel MPI-525 meter

Advanced solutions – measurements in networks, PV systems and EVSE

At the top of the Sonel range are the Sonel MPI-535, Sonel MPI-536, Sonel MPI-540, and the dedicated photovoltaic model Sonel MPI-540-PV (available both separately and in the Sonel MPI-540-PV Solar kit with much broader capabilities). These meters are designed for professionals who need a universal tool for working in various environments.  

Equipped with a 7-inch color touch screen, they offer extremely convenient operation, quick access to results (featuring a tree-structured memory), and the ability to program auto-tests that allow for a comprehensive installation check without the need to manually select individual functions. These models are capable of testing all types of RCDs: AC, A, B, B+, F, EV, making them compliant with the latest measurement requirements for EV charging station installations.

The most advanced model – Sonel MPI-540-PV – combines the functions of a top-tier electrical installation meter with an advanced PV system analyzer. It enables the measurement of PV string electrical parameters, irradiance measurement (in combination with the Sonel IRM-1 meter, available in the Sonel MPI-540-PV Solar kit or separately), and three-phase power quality recording. This allows the user to comprehensively assess the performance and safety of the entire installation: from PV modules to the grid connection.

 
Photo 3. Photovoltaic measurements using Sonel MPI-540-PV meter

Common safety and quality standards

Regardless of the model, every Sonel MPI series meter meets rigorous safety standards and is designed for operation in networks up to 500 V. The devices are equipped with automatic connection check functions and a system warning the user of incorrect lead connections.  

All models use the Sonel Reader (free) / Sonel Reports Plus software ecosystem, which enables archiving and analysis of measurement results. This allows installation test reports to be prepared easily and in accordance with applicable regulations.

In models with a graphical display, a context-sensitive help function is available. The user can call up a screen with clear function explanations and tips regarding the specific measurement.

Rich standard equipment and a wide range of optional accessories

The user receives a full set of test leads, probes, and crocodile clips, a power cord, batteries or rechargeable batteries with a charger, and a practical carrying case or transport case as part of the kit. Consequently, Sonel MPI devices are ready to work immediately after unpacking, without the need to purchase additional components.

Sonel also offers a very wide selection of optional accessories that allow for expanding measurement capabilities and tailoring the meter to specific user needs. The offer includes, among others, current clamps, earth measurement kits, adapters, and various types of measuring probes. A particularly practical addition is the LP-1 probe for measuring illuminance, compatible with the MPI-530, MPI-530-IT, MPI-535, MPI-536, MPI-540, and MPI-540-PV models. It enables the measurement of light levels in workplaces, office spaces, or industrial facilities, supporting compliance assessment with current standards.

 
Photo 4. Illuminance measurements - Sonel MPI-530 and LP-1 probe

Summary – a meter tailored to your needs

The Sonel MPI series is a comprehensive range of measurement solutions that evolves with the user's needs. It includes both simple models for everyday measurements and advanced instruments with power quality analysis and PV system functions. Every meter combines precision, reliability, and intuitive operation. Whether you are just starting your career as an electrician or performing professional acceptance and periodic measurements, you will find an instrument tailored to your tasks in the MPI series.

Device Group	Models	Key Functions	Typical User	Application
Basic installation meters	MPI-502F	Fault loop impedance measurement, RCD test (types AC and A), continuity of connections	Electrical installer, service technician, contractor performing periodic inspections	Installation inspection in residential and commercial buildings
Basic installation meters	MPI-506	Insulation resistance measurement with voltage up to 500 V, fault loop impedance measurement, RCD test (types AC and A), continuity of connections, phase sequence indication	Electrical installer, service technician, contractor performing periodic inspections	Installation inspection in residential and commercial buildings
Basic installation meters	MPI-507	Insulation resistance measurement with voltage up to 500 V, fault loop impedance measurement, RCD test (types AC and A), continuity of connections, earth resistance measurement, phase sequence indication	Electrical installer, service technician, contractor performing periodic inspections	Installation inspection in residential and commercial buildings
Professional mid-range	MPI-520	Insulation resistance measurement with voltage up to 1000 V, phase sequence test, power consumption measurement	Installation companies, industrial services, electrical auditors	Diagnostics of industrial installations, grounding systems and drives
Professional mid-range	MPI-525	Insulation resistance measurement with voltage up to 2500 V, phase sequence test	Installation companies, industrial services, electrical auditors	Diagnostics of industrial installations, grounding systems and drives
Professional mid-range	MPI-530 MPI-530-IT	Insulation resistance measurement with voltage up to 1000 V, phase sequence test, single-phase power quality recorder (MPI-530-IT – operation in IT networks)	Installation companies, industrial services, electrical auditors	Diagnostics of industrial installations, grounding systems and drives
Advanced solutions: universal models	MPI-535	Touch screen, auto-tests, insulation resistance measurement with voltage up to 1000 V, testing all RCD types (AC, A, B, B+, F, EV), operation in IT networks	Measurement specialists, energy auditors, maintenance engineers	Comprehensive protective measurements and power quality control
Advanced solutions: universal models	MPI-536	Touch screen, auto-tests, insulation resistance measurement with voltage up to 2500 V, testing all RCD types (AC, A, B, B+, F, EV), operation in IT networks	Measurement specialists, energy auditors, maintenance engineers	Comprehensive protective measurements and power quality control
Advanced solutions: universal models	MPI-540	Touch screen, auto-tests, insulation resistance measurement with voltage up to 1000 V, testing all RCD types (AC, A, B, B+, F, EV), three-phase power quality recorder, operation in IT networks	Measurement specialists, energy auditors, maintenance engineers	Comprehensive protective measurements and power quality control
Advanced solutions: specialized PV versions	MPI-540-PV (MPI-540-PV Solar)	Touch screen, auto-tests, insulation resistance measurement with voltage up to 1000 V, testing of all RCD types (AC, A, B, B+, F, EV), three-phase power quality recorder , operation in IT networks, measurement of photovoltaic installations, conversion of results to STC conditions	Installers and service technicians of photovoltaic systems, RES auditors	Comprehensive protective measurements and diagnostics and performance control of PV installations

If you want to compare the functions of Sonel MPI series meters in detail, use our product comparison tool.

 

Author:
Jacek Parafinowicz, Sonel S.A.