GENERATING SETS FOR MEDIUM/HIGH VOLTAGE MANAGEMENT SECTOR

Thanks to our experience and continuous research targeted towards technological innovation, Visa SpA offers solutions that are suitable for every requirement, also in the Medium Voltage range supporting customer needs starting from the design of the system, up to commissioning and the relative support and maintenance.

What is medium voltage?

Medium voltage = operating voltage above 1 kV and below 30 kV; mainly 10 kV – 15 kV - 20 kV High voltage = operating voltage above 30 kV, typically 60 kV - 150 kV

Applications that use medium voltage generating sets are particularly interesting and are increasingly used due to the clear advantages that they offer: • First of all, there is the considerable savings in copper cables for electrical power connections. Increasing the operating voltage proportionally decreases the current and the power distribution cables can therefore have smaller sections. This results in a reduction in the direct costs of the cables, but also in a reduction in the indirect costs related to their installation. • Reduction in noise thanks to the remote location of the plant with respect to the users. • Possibility to create a dedicated, logistically organised area for managing refuelling, which is fully remote controlled by intelligent remote-management systems.

The medium voltage applications are developed in two separate ways:

• Low voltage generating set + step-up transformer;

• Generating set with medium voltage alternator.

The decision regarding which design solution should be selected is made based on the size and characteristics of the plant to be powered In both cases, the medium voltage line is sectioned by the medium voltage cell, which is the equivalent to the low voltage/isolator. In this sector, Visa SpA is able to offer and provide medium voltage machines and the relative medium voltage cells using both design solutions as well as the best components available on the market. In addition to designing and producing the machines, Visa SpA is also able to support its customers during the plant design phase, providing services and materials also for implementation in existing plants. These types of projects are custom designed, working with the specific requirements and particular aspects of the installation on a case by case basis. Visa SpA uses a highly specialised team of engineers who follow the various steps of the project, especially for particularly complex and demanding projects, from the dimensioning to the manufacturing, from testing to installation, always in strict compliance with the specifications and requested deadlines. Furthermore, Visa SpA is also able to rent variable voltage transformer cabins that can be used both for the test phases (at the company or customer site) as well as during the maintenance or implementation of existing plants. For more information about the rental service for generating sets, twin packs, lighting towers, transformer cabins, containerized fuel tanks and the relative accessories please consult: www.visarent.it

Some examples of medium voltage projects are provided below

PLANT WITH USE OF A LOW VOLTAGE ALTERNATOR + STEP-UP TRANSFORMER

Generating plant in island (without Mains) for a military application in Algeria.

Design, manufacturing and supply of equipment used for powering a radio station, two overhead lines with 30 kVA, 50 Hz – 2.4 MVA. The medium voltage electrical system has 3 x 800 kVA transformers, 1 x 160 kVA for powering the central station auxiliaries and + 1 x 70kVA homopolar transformer, 1 medium voltage electrical cabinet with 8 protective, distribution and control compartments (cells), a low voltage electrical cabinet that fully manages the electrical power plant, a SCADA supervision system for the local and remote control of the plant. The generating sets supplied: 3 model P 805 S units, 800.0 kVA in PRP, special version, in parallel mode, each equipped with a dual pump diesel loading system and a diesel filtration stage with a control panel.

PLANT WITH USE OF A MEDIUM VOLTAGE ALTERNATOR

Generating plant in island (without Mains) for a railway application in Russia. Design, manufacturing and supply of equipment used for powering a railway system. Generating set model C 1250 MV, open version, 1260 kVA in PRP; 10.5KV - 50Hz - 3 phase - 1500rpm

Technical specifications:

• Cummins engine model KTA 50 G3
• 10.5kV alternator Mecc Alte model ECO46HV-1L/4 (1350 kVA)
• 2500 l. fuel tank mounted on board
• Control panel for parallel operation (“parallel manual and automatic start”) without a medium voltage cell, with current transformers (CT’s) and voltage transformers (VT’s) for line measurement and protection included.