MV Project Approval and Medium Voltage Design

Medium voltage installations design service covers the technical design of medium voltage electrical infrastructure above 1 kV and up to 36 kV in practice for industrial facilities, OIZ factories, power generation plants, large commercial buildings and infrastructure projects, in compliance with official authority processes and with engineering control during the implementation stage. As Pow-Sys Power Systems, we provide medium voltage installations engineering, MV installation design and MV project approval process support across Türkiye. For related context, see Electrical Installation Conformity Report and Periodic Inspection.

A medium voltage project is not merely a drawing preparation process. The facility’s energy demand, installed power, demand power, transformer capacity, MV switchgear structure, cable route, protection system, grounding arrangement, energy permit and official authority requirements must be evaluated together. For this reason, technical calculations, site conditions and authority approval requirements are handled as a whole during the MV installation design process. For related context, see Electrical Contracting Services.

The documents required for a medium voltage project may vary depending on the requirements of the connected distribution utility, OIZ, TEDAŞ or relevant authority. A typical file includes the energy permit, connection opinion, facility information, load list, installed power data, transformer capacity, single-line diagram, MV switchgear arrangement, cable route, technical calculations and application forms. For related context, see Electrical Periodic Inspection and Examination Service.

Before starting project studies, a site survey and existing condition analysis are carried out. Transformer substation, MV switchgear, low-voltage panels, cable connections, compensation system, grounding installation, metering circuits and previous project documents, if available, are reviewed. This study helps determine the correct project scope for a new facility installation, capacity increase, transformer capacity change or existing MV installation revision. For related context, see Short-Circuit Analysis, Relay Coordination and Selectivity.

One of the first steps in the design process of medium voltage installations is determining the energy demand correctly. Installed power, demand power, simultaneity, production lines, motor loads, generator connection, solar power plant connection, backup supply requirement and critical loads are evaluated together. These data form the main inputs for selecting transformer capacity, MV switchgear structure, cable sizes and protection system.

Energy permit and connection opinion are important stages in the MV project process. The technical requirements determined by the relevant distribution company, OIZ directorate or authority directly affect the project. Therefore, when preparing a medium voltage project, the power, connection point, voltage level, supply method and authority requirements stated in the energy permit must be carefully reviewed.

Within the scope of MV installation design, single-line diagram, load list, MV switchgear arrangement, transformer substation layout, cable route, panel layouts, grounding plan, cable sizing calculations, short-circuit calculations, voltage drop calculations and implementation projects can be prepared. When required, different project documents such as preliminary design, final design, implementation project, revision project and as-built project can also be created.

MV switchgear arrangement is one of the most critical topics in the medium voltage installations design process. Incoming cubicle, metering cubicle, transformer protection cubicle, outgoing cubicles, coupling cubicle and spare cubicle requirements should be planned according to the facility’s operating scenario. During switchgear arrangement, maintenance access, cable entry-exit directions, switching safety, operator use and official authority expectations are considered.

In MV installations with transformer substations, transformer capacity, transformer type, cooling structure, installation area, ventilation, fire safety, cable connection directions, maintenance access, transportation possibility and safety clearances must be evaluated together. During transformer substation design, not only the initial investment cost but also long-term operational safety and maintenance convenience are taken into account.

Short-circuit calculation is one of the fundamental parts of medium voltage installations engineering studies. Short-circuit levels are required for correct selection of MV switchgear, circuit breakers, disconnectors, busbars, cables, transformers and protection equipment. Equipment selected without calculation may fail to provide adequate safety during a fault and may put operational continuity at risk.

Voltage drop and cable sizing calculations are important for the healthy operation of loads supplied from MV installations. Cable lengths, load currents, route conditions, installation method, ambient temperature and voltage level are evaluated together to determine the appropriate cable size. This study is necessary for both energy efficiency and facility safety.

Grounding and surge arrester systems must also be carefully handled during the MV installation design process. The grounding system is critical for safely transferring fault currents to earth, ensuring life safety and protecting equipment. Surge arrester selection and lightning protection approach become especially important in open field, transformer substation and overhead line connection applications.

Protection coordination and relay selectivity studies ensure that the system responds correctly during faults in MV installations. The aim is to clear the fault only at the relevant point, keep healthy sections energized and prevent unnecessary trips. In this scope, short-circuit results, transformer data, circuit breaker characteristics, protection relay curves and operating scenarios are evaluated together.

When required, load-flow analysis, arc-flash risk assessment, harmonic effects, compensation behavior and power quality topics can also be evaluated during the medium voltage project process. These reviews help ensure that MV switchgear, transformers, cables, busbars and protection equipment are selected according to real operating conditions.

The MV project approval process is not completed only by preparing the drawings. The project file must be prepared according to the relevant authority requirements, technical calculations must be added to the file, application documents must be arranged, authority revisions must be tracked and the post-approval implementation process must be carried out in accordance with the project. Approval authority belongs to the relevant institutions; Pow-Sys Power Systems provides technical file preparation, revision tracking and engineering support.

EDAŞ, OIZ, TEDAŞ and EMO processes play an important role in medium voltage installations design studies. During project approval, application file, technical revision, official acceptance file, provisional acceptance, final acceptance and report processes, the documents must be consistent with the actual site condition. Facilities without an approved project or with site implementation that does not comply with the approved project may face problems during the acceptance stage.

Medium voltage installations design service may be required in many cases such as new facility investments, transformer substation installation, transformer capacity increase, MV switchgear renewal, overhead line connection, solar power plant connection, generator integration, panel revision, capacity increase, power quality problems or official authority approval processes.

MV project approval is the authority review and technical approval process for the prepared medium voltage project file. Acceptance is the field process that checks whether the on-site implementation complies with the approved project, authority requirements and technical safety conditions. Therefore, project approval and acceptance complement each other, but they are not the same process.

Correct transfer of the project to the site is also important during implementation. MV switchgear layout, cable route, cable terminations, transformer connections, grounding connections, panel connections, labeling, metering circuits and protection equipment should be checked on site. Conditions that do not comply with the project or may create operational risks in the future can be reported in writing.

During testing and commissioning, the necessary checks are carried out to energize the MV installation safely. MV switchgear, circuit breaker, disconnector, protection relay, transformer, grounding, continuity, metering circuits, compensation and other systems deemed necessary are tested and inspected. These studies also provide the technical basis for provisional acceptance and final acceptance processes.

During the quotation process, facility type, installed power, demand power, transformer capacity, number of MV switchgear units, existing single-line diagram, energy permit status, EDAŞ / OIZ / TEDAŞ process, cable distances, transformer substation condition, capacity increase information, site survey requirement and commissioning scope are evaluated together. This allows us to prepare a phased engineering proposal that reflects the real technical scope of the MV project process, rather than only a general price.

Pow-Sys Power Systems approaches medium voltage installations design not only as a project drawing service, but as an engineering study that considers energy continuity, operational safety, authority approval process, technical calculations, implementation control and long-term facility needs together.

For medium voltage installations design, MV installation design, medium voltage installations engineering, MV project drawing, MV project approval process, short-circuit calculation, protection coordination or EDAŞ / OIZ / TEDAŞ authority tracking, you can share your facility information and request a project-specific comprehensive engineering evaluation. Scope is clarified from this information, and before signing you see in writing what is included and what is planned as a separate service.