Electric Department -

Electric Department

The specialists of the company’s Electric Department carry out a full range of works including major repairs, reconstruction, modernization, and installation of high-tech equipment: turbo generators of all types, hydro generators, transformers, high-voltage motors, and synchronous compensators.

SCOPE OF WORKS INCLUDES:

Disassembly and assembly of generators with rotor removal for comprehensive diagnostics and troubleshooting
Gas-tightness testing of the turbo generator with mandatory detection and elimination of even minor leaks
Repair of the active steel – including detailed tests for power loss and heating to identify and eliminate hidden defects
Rekeying of stator slots to restore precise fitting and ensure reliable operation
Resoldering of stator winding heads with re-insulation to restore electrical characteristics and prevent possible damage
Replacement of molded compound insulation of rods and coils – a crucial step to enhance resistance to thermo-mechanical stresses
Conducting electrical tests, measurements, and hydraulic tests for comprehensive condition assessment and guaranteed safe operation of the generator

These tasks require high qualifications and extensive experience, which our company’s specialists possess.

The company has extensive experience in performing highly complex generator repairs, including the replacement of stator windings. Among the most significant projects are:

In 2015, repair of the TGV-200M generator at Kurakhivska TPP.

In 2017, repair of the TGV-200-MTZ generator at Gorazal TPP in Bangladesh.

In 2020-2021, major and then emergency repairs of the TVV-800-2U3 type generator No. 7 and the WT-6000 working exciter at Sloviansk TPP, including:

repair of rotor slot liners,

replacement of end boxes,

replacement of coils with restoration of the geometry of other coils and insulation.

Additionally, we actively cooperate with the division of JSC “Ukrainian Energy Machines” — the “Electrotyazhmash” plant, as well as other manufacturers and suppliers of generator spare parts. This enables us to provide customers with comprehensive repair services including the supply of necessary spare parts, ensuring a full cycle of technical support for the equipment.

During the major overhaul of generators, specialists at Kharkivenergoremont-Holding perform a comprehensive set of works aimed at restoring the reliability and safety of the equipment.

Specifically, the following tasks are carried out:

Repair of slip rings with insulation replacement
Repair of fans and current leads
Checking gas tightness and hydraulic tightness
Repair and replacement of banding and slip rings
Repair of current conductors, replacement of insulation, central conductor, and busbar
Restoration and replacement of rotor winding coils
Wedge replacement in rotor slots, repair and replacement of sub-banding insulation
Repair of brush-contact apparatus, turning and grinding of slip rings
Repair of gas coolers
Repair and manufacturing of stator winding end leads
Repair of the generator’s gas system

Each of these stages is performed in compliance with high-quality standards and safety regulations.

Thanks to thorough inspection and renewal of key components, the generators gain a “new life” — ready for uninterrupted operation under increased loads and the modern demands of the energy sector.

A separate area of work within the Electrical Department is the major overhaul of transformers with voltage classes from 6 kV to 750 kV and capacities ranging from 1 MVA to 1250 MVA.

Since 2017, when the equipment for transformer repairs was significantly upgraded and modernized, more than 40 repairs of various types of transformers have been completed both at power plants and energy facilities in Ukraine and abroad (including 5 transformers at the Moldovan GRES in 2021 and 4 transformers at the Gorazal Thermal Power Station in Bangladesh in 2017).

In 2019, a major overhaul was performed on transformer T1 of type TDC-250000/330 at the Tashlyk Pumped Storage Power Plant.

In 2019–2020, about 20 transformer repairs were carried out at facilities of SE NNEGC “Energoatom,” mostly at the South Ukraine NPP, as well as at the Rivne NPP and Khmelnytskyi NPP. These included repairs of the most powerful block transformers in Ukraine of type TNC-1 250 000/330, transformers at switchgear units, and autotransformers of types TNC-1250000/330, AODCTN-333000/750/330/150, ATDCTN-250000/330/110-U1, TRDCN-63000/330, TDC-250000/330, and shunt reactors RODC-110000/750.

Repairs have also been performed on transformers at Dobrotvirska TPP and Kryvorizka TPP of DTEK company, at the South-Western Railway, Dnipro division of NEC “Ukrenergo,” Poltavaoblenergo, and several industrial enterprises.

In 2023, emergency and major repairs were carried out on transformers of type TDC-430000/330-UHL1, units №T-3 and №T-4, at the Dniester Pumped Storage Power Plant.

SCOPE OF TRANSFORMER REPAIR WORKS INCLUDES:

Dismantling of transformer components (expansion tank, exhaust pipe, bellows-type filter)
Removal of bushings
Opening and repair of the active part
Repair of the removable part of the tank
Repair of the tap changer
Repair of the cooling system
Repair or replacement of bushings
Installation of components, assembly of the transformer
Sealing of the active part of the transformer
Draining, processing, and degassing of transformer oil
Electrical testing and analysis of oil and solid insulation

Additionally, the following works are also performed during major transformer repairs:

Heavy lifting and moving operations using hydraulic jacks and pushers with capacity up to 400 tons
Drying and dehydration of transformer insulation
Restoration of transformer oil properties (drying, cleaning, degassing, regeneration)

As with other types of power equipment, alongside transformer repair works, we also offer our customers the supply of spare parts and consumables. Thanks to close ties and partnership relations with the Zaporizhtransformator plant and other Ukrainian and international manufacturers, we organize the supply of high-voltage bushings, gas and jet relays, flexible shells, components for cooling systems, quality rubber for seal replacements, butterfly valves, and other spare parts.

Main Types of Work in Hydropower

The company has extensive experience in the repair, modernization, and installation of hydropower equipment both in Ukraine and abroad. We offer overhaul, reconstruction, installation, and commissioning of hydroelectric and hydromechanical equipment for hydroelectric power plants and pumping stations. Our work covers all well-known structural types of hydro units.

We also have experience in comprehensive solutions for the modernization and reconstruction of small hydropower plants. We provide repair and restoration services for non-standard equipment using advanced repair technologies.

Specialists from the electrotechnical department participated in the reconstruction of all hydroelectric power plants of the Dnipro cascade, specifically in the modernization of hydrogenerators with stator winding replacement.

In 2013, a major overhaul of hydro unit No. 1 at Krasnooskolska HPP was completed.

In 2021, at the “Sendje” Hydroelectric Power Station in Equatorial Guinea, company specialists carried out the installation and anti-corrosion protection of penstocks with a diameter of 5000 mm. The work was performed under challenging conditions that required high precision and responsibility, as this was a key element of the hydraulic structure. The project became an important milestone in the company’s international activities and confirmed its ability to effectively implement large-scale technical tasks beyond Ukraine.

Installation of Penstock Pipelines at Sendje Hydropower Plant, Equatorial Guinea

The photo captures the process of installing large-diameter steel penstock pipeline sections, which are a critical element of the hydrotechnical infrastructure of the hydropower plant. The work includes foundation preparation, installation of supporting structures, alignment, and welding of the pipeline sections.

The installation is carried out using heavy machinery, specialized rigging solutions, and skilled personnel in accordance with international quality and safety standards.

Positioning of SRwS 4-2 Section for Installation

The delivery and preparation for installation of the next SRwS 4-2 penstock pipeline section is underway. The work includes precise positioning of the element, verification of geometric parameters, preparation of joints, and ensuring installation tolerances in accordance with the project documentation. Strict adherence to the technological sequence and welding requirements is ensured to guarantee the pipeline’s tightness and reliability.

Repair Works on the Hydroturbine of Unit No. 5 at Shulbinsk HPP, Kazakhstan

Stator Winding Cleaning

The stator winding cleaning procedure is performed using a specialized cleaning solution under pressure to remove dust, process residues, insulation material remnants, and oils accumulated during operation or maintenance. This method effectively restores the electrical insulation properties of the surface, reduces the risk of insulation breakdown, and enhances the reliability of the generator. After cleaning, drying is conducted, insulation resistance is tested, and a visual inspection is performed to detect any mechanical damage.

Installation of the Hydroturbine at Unit No. 5, Shulbinska HPP

Installing a hydroturbine after repair is always a critical and intense stage:

The photo shows a large-scale turbine component undergoing the final preparation phase after major overhaul.

This is not just a repair — it is a revival of an entire energy facility that supplies electricity to thousands of people.
The responsibility of engineers and installers is at its highest here: no mistakes are allowed, and every step is strictly controlled.

Thanks to the specialists’ work, Shulbinska HPP receives a new impulse for stable operation, and the team takes pride in their contribution to the country’s energy security.

Photo: Runner wheel of the hydroturbine at Unit No. 5, Shulbinska HPP

This component receives the powerful water flow and converts its energy into rotational movement, which drives the generator and ensures electricity production for thousands of households and businesses.

The condition and precision operation of this element determine the overall efficiency of the power plant, the stability of the energy system, and the safety of the facility.

During the work, we performed full restoration of the functional surfaces, conducted balancing, and prepared the equipment for further operation. This extends the service life, prevents emergency situations, and guarantees reliable power supply to thousands of consumers.