Page 7 - Energize June 2022
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        insulation material for the transformer.   to consult with the manufacturer to ensure there is sufficient natural or forced air flow in
        This means that air is used instead of   the area with old or new installations.
        oil as the cooling medium as well as the   Where necessary, CRTs can be built into enclosures suited to a particular application,
        insulating medium. This is good news   even for outdoors. Should the unit be installed in an area exposed to lightning, suitable
        because no oil means no leaks and no   lighting arrestors must be installed on the main incoming MV line. Should MV switchgear
        fire.                                be installed close to the CRT, it is highly recommended that surge suppression devices are
           Consequently, CRTs can be regarded   installed to protect against unwanted switching over voltages.
        as a “green technology”, with no fire   CRTs are essentially maintenance free. Minor inspections, checks and cleanings are all
        hazards due to the self-extinguishing   that is needed to successfully maintain these transformers. Transformer manufacturers will
        medium used in the CRT, and          usually assist with maintenance when requested. Replacing critical parts is easy because all
        conformance to other safety, health   the CRT’s major parts are accessible.
        and environmental (SHE) requirements,   Distribution CRTs have been successfully installed and used in Southern Africa in
        saving installation costs on a new   the last ten years or so in various industries including mining, renewables, municipal,
        project.                             commercial, industrial and telecommunications. These applications often have unique
           The fact that there is no oil to   specifications according to the needs of the project or client. It is always wise to consult
        worry about, also makes life easier as   with the manufacturer and provide as much information as possible regarding the
        the regular maintenance regarding    project, to allow the manufacturer to assess the requirements, and design a CRT to meet
        transformer oil is no longer needed.   international specifications (such as IEC/SANS 60076-11 : 2020) and your client’s particular
        Oil transport and on-site oil filling is no   specifications.
        longer necessary. Oil bund walls are   Consultants are advised to familiarise themselves with the differences in the type test
        not needed to contain oil spills. CRTs   requirements for CRTs when compared to oil-filled transformers, as specified in
        ensure that safety and environmental   IEC/SANS 600676-1.
        issues which might be regulatory, or
        required by specific projects or clients,      When considering your next distribution transformer installation, keep the following
        are complied with. Insurance costs for   advantages of CRTs in mind:
        the installation of a CRT in high-risk areas   •  Environmentally friendly
        should be much lower too because of    •  Fire and flame retardant
        the low risk of fire. Typical application   •  Can easily be designed and installed according to needs
        examples include power stations,       •  Compact dimensions
        substations, hospitals, high rise buildings   •  Ease of maintenance and visual checks
        and shopping malls.                    •  CRTs can be recycled if necessary
           A CRT’s protection system is based   •  Low installation cost
        on the heat generated by the windings   •  Low noise levels
        during normal operation. This is easily   •  High efficiency
        done with a simple thermal protection   •  Lower insurance costs
        device connected to thermo couples. The   •  Small installation footprint
        thermal protection device is set to the   •  No contamination as there is no mineral oil used
        needed value (according to insulation   •  No need for oil protection bund walls.
        class and manufacture) and can provide   •  Ease of visual inspections of windings and assembly during manufacture, testing
        an alarm and trip signal should these     and commissioning.
        values be reached. In addition to the
        above, fans could be added to the    Conclusion
        thermal protection device should it be   Oil-filled transformers will never be completely replaced in Southern Africa; however,
        desirable to control the transformer’s   from the above information provided, we hope you will consider CRTs for future projects
        temperature.                         as they have a smaller environmental footprint and many other added advantages. All the
           Regarding the installation of a CRT,   advantages will save project and maintenance cost in the long run and lead to a greener
        there are some key factors to consider.   world for future generations.
        CRTs are IP 00 with all electrical

        connections exposed. Thus, there is   Contact Paddy Padayachee,
        a risk of environmental exposure and   Revive Electrical Transformers,
        contact. It is recommended that the   Phone 082 560-8953, or
        installation area be assessed to ensure   Zander van Rooyen,
        that all necessary ventilation and safety   Phone 076 751-3386,
        requirements are met. As the CRT uses,           R E     V I V  E

        natural air as cooling, it is very important   REVIVE ELECTRICAL TRANSFORMERS (PTY) LTD

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