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.