When carrying out power transformer repair work, we use high-quality materials and components from leading global manufacturers.
Use of Components from Leading Brands
High-Voltage Bushings
Oil–Air, Oil–Oil, Oil–SF₆, with solid RIP insulation, oil-filled, with porcelain or polymer housings.
On-Load Tap-Changers (OLTCs)
Hyundai Heavy Industries Co. Bulgaria has been manufacturing OLTCs for over 60 years. More than 50,000 units have been produced during this period, securing the company a leading position in this market segment.
The equipment has been tested in independent international laboratories, including KEMA (Netherlands), VUSE (Czech Republic), and KERI (South Korea), and has been approved by power utilities in multiple countries.
Design flexibility, compact dimensions, high technical characteristics, and operational reliability ensure compliance with technical specifications and delivery requirements.
Maschinenfabrik Reinhausen GmbH (MR), founded in 1868 in Regensburg, is the core company of the Reinhausen Group, which comprises 38 subsidiaries and 6 affiliated companies worldwide.
The primary activity of MR is the development and production of equipment for the regulation of power transformers. Regulation is carried out using OLTCs, which adjust the transformation ratio in accordance with load conditions. In combination with other MR products and services, these devices ensure reliable power supply.
Radiators, Oil Coolers
Protective Relays, Type BF (Buchholz Relays) manufactured by EMB, Germany
Used as a protective device, responding to transformer faults such as gas formation during operation and loss or leakage of insulating liquids.
The relay is equipped with an electrical trip system, which is activated in case of:
- Gas accumulation
- Leakage of insulating liquids
Monitoring Relay for On-Load Tap-Changer (ÜRF)
The monitoring relay for the on-load tap-changer, also referred to as a protective relay for the tap-changer or an oil flow relay, is a monitoring device for oil-insulated tap-changers with an expansion tank. Its function is to protect the tap-changer and the transformer from damage.
The relay responds to inadmissibly high oil flow velocities towards the expansion tank and issues a signal that immediately disconnects the tap-changer and the transformer from the voltage supply.
Pressure Relief Device LPRD 00, manufactured by Qualitrol, USA
The device is used for rapid release of a large volume of gas or insulating liquid when the internal pressure of the transformer reaches a preset level.
- Relief setting: from 5 PSI to 15 PSI (0.35 bar to 1.0 bar)
- Features: equipped with an electronic signal analyzer for valve activation
Temperature Sensors
These devices are used for monitoring the temperature of transformer oil and windings:
- Oil temperature sensor, type AKM 34 (Switzerland)
- Winding temperature sensor, type AKM 35 (Switzerland)
- Oil temperature sensor, type MT-ST160 “MESSKO” (Germany)
- Winding temperature sensor, type MT-STW160F2 (Germany)
Application:
- Measurement of oil and winding temperatures in power transformers and reactors.
Features:
- Designed for long service life without additional maintenance.
- Suitable for outdoor installation on the transformer or direct installation inside the control cabinet.
- Reliable operation in various climatic conditions.
Shut-Off Valves, Type RDR-MKII, manufactured by COMEM, Italy
These valves are designed to block the flow of oil into the transformer in the event of excessive oil flow, malfunctions, or fire.
Features: equipped with an electronic signal analyzer that triggers the valve.
Rapid Pressure Rise Relay 900-009-67, manufactured by Qualitrol, USA
The relay is designed to provide an “alarm” signal in the event of a rapid increase in oil level within the transformer tank.
Air Dryers, Types DB 100 and DB 200, manufactured by Messko, Germany
Silica gel mass: 1.1 kg to 2 kg
Features: equipped with a self-regenerating silica gel drying system
Flexible Tank Liner, Type OLM, manufactured by Musthane, France
Used in the transformer tank to prevent contact between the insulating oil and the external environment.
Instrument Transformers, KONČAR, Croatia
The main types of instrument transformers produced by KONČAR – INSTRUMENT TRANSFORMERS Inc.:
- Oil-insulated current transformers, type AGU: 110 to 750 kV
- Capacitive voltage transformers, type VCU (oil-insulated): 110 to 750 kV
- Inductive voltage transformers, type VPU (oil-insulated): 110 to 500 kV
- Combined transformers, type VAU (oil-insulated): 110 to 330 kV
The KONČAR name is recognized worldwide and is synonymous with high quality and reliability.
Motor Drive (MZ)
The drive is mounted vertically on the exterior of the transformer tank (bell-type or other) and is convenient for operation and maintenance.
- Design: Developed to meet operational requirements in all climatic conditions
- Standards compliance: IEC 60214-1:2003
- Type MZ-4.4: Complies with ANSI standards
| Parameter | MZ 4.4 | MZ 4.1 | Unit |
|---|---|---|---|
| Rated motor power | 0.75 / 1.1 (0.9 / 1.3 at 60 Hz) | 0.75 / 1.1 (0.9 / 1.3 at 60 Hz) | kW |
| Rated frequency | 50 / 60 | 50 / 60 | Hz |
| Supply voltage | 3 AC 400 / 230 | 3 AC 400 / 230 | V |
| Synchronous speed | 1500 (1800 at 60 Hz) | 1500 (1800 at 60 Hz) | rpm |
| Handle revolutions per switching | 33 | 33 | revs |
| Rated output shaft torque | 17 / 24 | 17 / 24 | Nm |
| Switching duration | 4.5 | 4.5 | s |
| Maximum number of tap positions | 38 | 38 | — |
| Control circuit voltage | AC 230 | AC 230 | V |
| Insulation level | 2.5 | 2.5 | kV |
| Heater power | 250 | 2 × 150 | W |
| Degree of protection | IP54 | IP54 | — |
| Weight | 104 | 80 | kg |
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