Sonel MPU-1 | Leakage Current Alarm Signaller for LV MV HV Networks

Published 06 Nov 2018

Sonel MPU-1

Sonel MPU-1

  • uploaded by Chris Dodds - Thorne & Derrick Sales & Marketing Manager

Overhead Line Safety Monitoring

Sonel MPU-1 leakage current alarm signaller is designed to be installed to measure AC leakage current in low LV and medium voltage MV power networks.

Repairs, renovation, reconstruction, and modernisation of medium voltage overhead live lines always involves the potential risk and danger of breakdown, accident, arc flash or electric shock to employees who are doing the work.

These risks can be minimised through the use of appropriate personal protective equipment such as insulating mats, electrical insulating gloves, dielectric boots and non-flammable clothing.However all these safety measures will not detect increasing current flowing through the pole grounding, that if too high of a level can be the first warning of danger

Sonel MPU-1

Sonel MPU-1

The Sonel MPU-1 is designed to make measurements which can define the medium voltage power network’s safety condition for leakage current.

The device enables a limit to be set for a maximum safe value of flowing leakage current and for values above this limit visual and sound alarm is activated. The preset minimum current level where the loud audible alarm with a warning light signaling is switched is 1 A, in accordance with the PTPiREE guidelines.

♦  PTPiREE Polish Power Transmission and Distribution Association was established on 29 August 1990. PTPiREE is an association of the Distribution Network Operators (Enea Operator, Energa – Operator, PGE Dystrybucja, Tauron Dystrybucja, innogy Stoen Operator and PKP Energetyka) and the Transmission Network Operator (PSE). It works for the transformation of the Polish power industry, aiming to improve the operational efficiency of the LV MV HV power network, as well as the quality of services and customer service. Its operation includes consulting, training and publishing.

Contact us NOW to request FREE DEMO

Contact us NOW to request FREE DEMO

Using the leakage current alarm signaller it is also possible to manually set a different minimum alarm in the range from 0.5 to 9.9A (with the possibility of an increased alarm range at the time of manufacture for individual needs).

MPU-1 is dust and water proof to IP-67 in accordance with EN 60529 and can operate in temperatures from -10° to +50° C. The device is supplied in a hard carrying case for easy transport also with additional accessories to the workplace and protects against dirt or accidental damage.

Leakage Current Alarm Signaller for LV HV HV Networks - Sonel MPU-1

Sonel MPU-1

Sonel MPU-1


  • Constant monitoring of current flowing on earthing
  • Measurement with the use of single clamp or two clamps simultaneously. In the case of using two clamps, current value is summed up, which allows for checking twin pylons (rotational), with independent clamp for each component pylon
  • Work mode LED indicator
  • Visual and sound alarm (built in speaker) in the case of a higher value of leakage current than the defined limit (factory default set to 1A)
  • No DC current measurement
  • Measurement with flexible clamps (Rogowski coil) – Sonel F series
  • Measurement in 50 Hz or 60 Hz frequency low and medium voltage networks
  • Auto ranging
  • Battery level monitoring
  • Ergonomic handling
  • MPU-1 for operation requires F1, F-2 or F-3 clamp (additional accessories)

The leakage current alarm signaller can be connected to measure a power network or device according to the pictures below:

Device Working with Single Clamp Device Working with Two Clamps Work in medium voltage mode – alarm limit value and battery level can be seen on the screen Work in low voltage mode – value of current measured with the clamp and battery level can be seen on the screen Inputs in MPU-1 Signal
Pic 1 Device Working with Single Clamp Pic 2 Device Working with Two Clamps Pic 3 Work in medium voltage mode – alarm limit value and battery level can be seen on the screen Pic 4 Work in low voltage mode – value of current measured with the clamp and battery level can be seen on the screen Pic 5 Inputs in MPU-1 Signal


Leakage current measurement with clamp

Display Range Resolution Accuracy
0.1..9.9A 0.01A ±(5% m.v. + 2 digits)
10..99A 0.1A ±(5% m.v. + 2 digits)

Sonel MPU-1 Leakage Current Alarm Signaller

Technical Specification

Degree of housing protection acc. to EN 60529 IP67
Max. noise voltage AC+DC, for which measurement is possible 24 V
Max. measured noise voltage 100 V
Power supply SONEL bartery package NiMH 9,4V 2,4Ah
Operating time for standby mode >20h
Operating time for alarm mode >3h
Dimensions 125 x 150 x 95 mm
Weight (including battery) ok. 1,1 kg
Working temperature -10..+50 ˚C
Charger working temperature +10..+35 ˚C
Reference temperature 23 ±2 ˚C
Storage temperature -20..+80 ˚C
Relative humidity 20..85%
Relative nominal humidity 40..60%
Altitude (above sea level) <2000m
Quality standard Design and manufacturing are ISO 9001 compliant
The product meets EMC requirements the following standards (Immunity for industrial environment) according to EN 61326-1:2006 and EN 61326-2-2:2006


Standard accessories:

  • Carrying case L5- Sonel WAWALL5
  • Power supply adaptor Z11- Sonel WAZASZ11
  • Cable for charger – Sonel WAPRZLAD230
  • Mounting strap – Sonel WAPOZOPAKPL

Additional accessories:

  • F-1 clamp (ø 38 cm) – Sonel WACEGF1OKR
  • F-2 clamp (ø 25 cm) – Sonel WACEGF2OKR
  • F-3 clamp (ø 12 cm) – Sonel WACEGF3OKR
  • Lead for battery charging from socket of car lighter (12V) – Sonel WAPRZLAD1212V2

Should you require any further information about Sonel MPU-1, The Leakage Current Alarm Signaller, for LV MV HV Networks, please do not hesitate to contact Thorne & Derrick.

Overhead Line Equipment

Thorne & Derrick hold an up to date library of product approvals across the power transmission and distribution sectors including all UK DNO’s drawing on information from the DNO G81 documents, National Grid Asset Codes and Network Rail PADS approvals – we distribute substation and overhead line power grid infrastructure products for 11kV/33kV/66kV/132kV networks. This complemented by the most extensive range of Joints, Terminations & Connectors for the installation of medium/high voltage cable networks into substation switchgear, transformers and overhead lines.

Overhead Line Equipment

Further Reading