Technical Office – Electrical Department

  • The electrical section of the Coemi technical office guarantees customers a wide and complete range of services, and in particular:
    Consultancy for the definition of the best technical solution and assessment of the feasibility and costs associated with a new investment or revamping of an existing plant (feed engineering);
  • Network studies and coordination of electrical protections;
  • Detailed engineering and precommissioning services and subsequent commissioning of equipment and materials;
  • Works management and assembly assistance;
  • Primary injection services for the quality certification of a new plant and / or within a structured preventive and predictive maintenance program (condition base maintenance);
  • Secondary injection services (relay test and measurement instrumentation) for the certification and start-up of a new plant and / or as part of a periodic maintenance program;
  • Troubleshooting for LV and MV power cables and signal cables;
  • High performance control and supervision systems (electric scada);
  • Training courses for the customer’s staff.

Basic and detailed engineering

  • Network studies:
  • Load analysis;
  • Calculations of c.to c.to (IEC 60909, IEC 61363);
  • Calculation of load flow and engine start-up;
  • Studies of selectivity and coordination of protections;
  • Arc Flash Hazard analysis (IEEE 1584);
  • Basic engineering:
  • Consultancy for the definition of the best technical / economic solution for the modification and revamping of an existing plant;
  • Feasibility analysis and definition of the investment budget for the revamping of AT / MT and MT / BT electrical substations;
  • Cost estimates for the construction of new plants;
  • Assistance in relations with ENEL and for the connection of new AT and MT systems.
  • Detail engineering, commissioning and precommissioning:
  • Technical specifications for the supply of MV and LV switchboards, transformers and power factor correction systems;
  • Definition of the architecture of electrical protection systems and supervisory and control systems;
  • Detailed engineering for the supply of emergency electrical systems and related switching systems for the electricity grid / generator;
  • Detailed engineering for the connection of cogeneration plants and production from renewable sources to the AT and MT network of the public distributor;
  • Engine engineering of load shedding and motor re-acceleration systems;
  • Customer assistance for the pre-commissioning of electrical equipment and control systems;
  • Adjustment of delivery points and interface systems with the distributor network’s MT network and related adequacy certifications (DIDA, A70, A72, etc.);
  • Commissioning and assistance for the start-up of MV and LV electrical panels and transformers;
  • Programming and commissioning of electrical protection systems and SCADA systems;
  • Pilot-wire protection systems using the IEC 61850 protocol.

Training courses and manuals

  • Manual editing and operating instructions for the management of electrical systems;
  • Training courses for the customer’s operation and maintenance personnel;
  • Consultancy for the efficient management of electrical systems;

Commissioning and services for periodic and predictive maintenance

  • Customer assistance for the preparation of the periodic and predictive maintenance program for electrical equipment;
  • Secondary injection (commissioning and periodic tests of electrical protections):
  • Programming of Siemens Siprotec protection devices, Thytronic Pro-N, Schneider Sepam, etc .;
  • Verification of the calibration of the protection devices (verification of voltage, current and trip times) with relay test box.
  • Primary injection:
  • Diagnostics on power transformers
  • Insulation resistance measurements and polarization index;
  • Measurement of the winding capacity, delta tangent and delta tangent delta;
  • Short-circuit test and measurement of leakage inductance;
  • Measurement of transformation ratios and excitation current;
  • Measurement of winding resistance;
  • Measurement of additional frequency step losses;
  • Measurement of losses and of the no-load absorbed current;
  • Dielectric response analysis (DIRANA);
  • Analysis of the frequency response of the winding (SFRA);
  • Measurement of partial discharges.
  • Diagnostics on amperometric and voltometric transformers:
  • Insulation resistance measurements and polarization index;
  • Measurement of ratio error and angle error;
  • Survey of the excitation characteristic and saturation knee;
  • Measurement of winding resistance;
  • Polarity checks.
  • Periodic testing and testing of the AT and MT circuit-breakers:
  • Measure opening times, closing times and poly discrepancies;
  • Measurement of the static and dynamic resistance of the main contacts;
  • Measurement of excitation voltage and coil absorptions;
  • Measurement of the absorption of the spring-loaded motor.
  • Testing and diagnostics of MT electric motors:
  • Insulation resistance (RI);
  • Polarization index (IP);
  • Tangent delta and delta tandelta;
  • Partial discharge (PD’s).
  • Periodic checks for the AT drains:
  • Measurement of the third harmonic component of the earth leakage current.

Troubleshooting and tests on electric cables:

  • Troubleshooting on MV cables, measurement of DC discharge, ecometrical pre-location with ARM method, ICE and Decay, precise localization with acoustic method
  • Search for the cable route;
  • Troubleshooting on bt cables and on signal power cables;
  • Rigidity tests up to 60kVrms VLF 0.1Hz.

Our tools

Search for cables in a bundle

Test bench for AT and MT circuit-breakers

Ground resistance measurements and pitch and contact voltages

Single-phase test bench for primary injection (TA, TV, power transformers, etc.);

Microphone for "acoustic" troubleshooting

Verification of the aging state of the oil and of the impregnated insulating paper in the transformers

Hexaphase test bench for secondary injection (relay test)

Class A power quality analyzer

E-meter for troubleshooting signal and LV cables

AC insulation measurements up to 12kV (delta tangent)

Measurement of partial discharges in the motor stator windings

Quality analyzer for SF6 gas

AT pulse meter / generator for troubleshooting MT cables

Check batteries batteries

Measurement of transformation relationships

Voltage generator up to 110Vdc and 77Vac

SF6 gas treatment trolley

Verification of the aging state of the oil and of the impregnated insulating paper in the transformers

Trouble shooting and cable route BT and MT

VLF generator up to 60kV@0.1Hz