What is MV Title? What is it for, how does it work and what types are there?

MV head is a special cable accessory used for the safe and controlled termination of the end part of the medium voltage cable. Briefly, the answer to the question of what an MV title is; It is the termination element that securely connects the cable to a switchgear, transformer, busbar system or outdoor connection. This equipment not only provides mechanical connection; It also maintains insulation integrity, controls the electric field and helps protect the cable end against external environmental influences.

The answer to the question of what the MV header does is broader than just saying it connects the cable. At medium voltage level, the cable shield and insulation structure terminate at a certain point. At this point, if the electric field is not managed properly, surface tension may increase in the head area, scar formation may occur, and there may be a risk of failure over time. The main task of the MV header is to make this electrical stress safe by providing stress control in the screen termination area of ​​the cable. At the same time, moisture sealing, mechanical protection and safe equipment connection are also within the scope of the head.

Electric field control is at the heart of the MV header operating principle. In medium voltage XLPE or similar insulated cables, the conductor screen and insulation screen continue according to a certain order. Since this screen structure ends when the cable end is terminated, the field density tends to increase, especially in the screen cut area. Stress control elements inside the head make this transition more controlled. Thus, the electrical strain at the cable end decreases, the surface performance improves and the service life of the head is extended.

Therefore, the MV head is not an ordinary cable lug connection. It contains insulation support, stress control, external surface protection, sealing and, in most designs, trace tracking and an erosion-resistant material structure. Especially in outdoor applications, considering the effects of rain, UV, pollution and moisture, the head must provide not only electrical but also environmental resistance. Therefore, MV header selection should not be made only by looking at the cross-section and voltage value.

MV headsets can generally be classified as indoor and outdoor types. Indoor MV headers are used in cubicle, panel or closed facility connections. Outdoor MV headers are preferred in areas exposed to weather conditions, pole-top transitions or open switchgear applications. In outdoor types, shield structure, surface leakage path and environmental resistance are more prominent. In indoor types, compactness and equipment compatibility may be more important.

Another important class is separable or plug-in headers. This type of headers are especially used in RMU, GIS, compact MV cubicles and transformer bushing connected systems. The cable end is connected to the equipment via a plug-in and fully insulated connection system, instead of a direct open type termination. This approach can provide significant advantages in terms of site safety, compact installation and ease of maintenance. Plug-in titles have become quite common, especially in modern MV distribution structures.

MV cap technology is available in heat shrink, cold shrink or pre-molded silicone based systems depending on the application. In heat shrink systems, the material is placed on the cable by applying heat. In cold shrink systems, the elastomer structure is opened over the support tube and when the support is removed, the material fits tightly onto the cable. Pre-molded or separable solutions are especially preferred for standardized equipment connections. Which type is suitable is determined by site condition, equipment type and workmanship expectations.

MV header and additional bell are not the same equipment. The header connects the end of the cable to an equipment or open termination point. The additional bell is used to join two cables together. Even though they are both MV cable accessories, their functions are different. Mixing these two pieces of equipment in the field can lead to wrong material selection and serious operating errors. If the cable line is to be terminated, a header is used; if two separate cables are to be combined, an additional bell is used.

The healthy operation of the MV headset does not only depend on the quality of the material. Cable preparation process, screen cutting size, proper removal of the semiconductor layer, preparation of the conductive end, shoe tightening, sealing arrangement and correct placement of the stress control element directly affect the result of the job. For this reason, a significant portion of MV header failures are related to incorrect application and workmanship errors. Even the best material can fail with improper installation.

When choosing a header, the voltage level of the cable, number of cores, conductor cross-section, cable type, shield structure and the equipment to be connected should be taken into consideration. For example, the same header is not used for transformer connection, GIS cell, RMU connection or outdoor termination. In addition, installation environment, UV exposure, pollution level and mechanical layout constraints also affect the selection. For this reason, choosing MV headgear is not something that can be done randomly from the accessory catalogue.

The header area is one of the most sensitive points in medium voltage cable systems. Because while the cable body is produced under controlled conditions in the factory, the cap is often applied in the field. This makes header quality directly related to field discipline and installation experience. This is the main reason why a significant portion of faults occur in termination areas. Therefore, header assembly is considered one of the most critical work items in MV cable systems.

In summary, the MV title; It is a special cable accessory that provides safe, leak-proof and electrically controlled termination of medium voltage cable. It can be indoor, outdoor or separable; Can be applied with heat shrink, cold shrink or pre-molded designs. A correctly selected and correctly installed MV header is as important as the cable itself for the reliability of the cable system. If MV cable header selection, header-joint applications, RMU or transformer connections and MV field suitability will be evaluated together in your facility. HV/MV testing, maintenance and repair with LV/MV/HV project design and consultancy services can support the technical decision process.