Instructions for use of MV equipment: Difference between revisions
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The purpose of this chapter is to provide general guidelines on how to avoid or greatly reduce MV equipment degradation on sites exposed to humidity | The purpose of this chapter is to provide general guidelines on how to avoid or greatly reduce MV equipment degradation on sites exposed to humidity | ||
and pollution. | and pollution. | ||
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== Use under severe conditions == | == Use under severe conditions == | ||
Under certain severe conditions concerning humidity and pollution, largely beyond the normal conditions of use mentioned above, electrical equipment can be subject to damage by rapid corrosion of metal parts and surface degradation of insulating parts. Examples of suitable measures of protection against condensation and pollution are listed below. | |||
Under certain severe conditions concerning humidity and pollution, largely beyond the normal conditions of use mentioned above, electrical equipment can be subject to damage by rapid corrosion of metal parts and surface degradation of insulating parts. Examples of suitable measures of protection against condensation and pollution are listed | |||
=== Remedial measures for condensation problems === | === Remedial measures for condensation problems === | ||
[[File:humid_conditions.svg]] | |||
* Carefully design or adapt substation ventilation. | * Carefully design or adapt substation ventilation. | ||
* Avoid temperature variations. | * Avoid temperature variations. | ||
* Eliminate sources of humidity in the substation environment. | * Eliminate sources of humidity in the substation environment. | ||
* Install an | * Install an '''H'''eating, '''V'''entilation, '''A'''ir '''C'''onditioning unit (HVAC) | ||
* Make sure cabling is in accordance with applicable rules. | * Make sure cabling is in accordance with applicable rules. | ||
=== Remedial measures for pollution problems === | === Remedial measures for pollution problems === | ||
[[File:polluted_conditions.svg]] | |||
* Equip substation ventilation openings with chevron-type baffles to reduce entry of dust and pollution especially when the transformer is installed in the same room with switchgears or controlgears. | * Equip substation ventilation openings with chevron-type baffles to reduce entry of dust and pollution especially when the transformer is installed in the same room with switchgears or controlgears. | ||
* Install the transformer in a different room to use more efficient ventilation grids if any, | * Install the transformer in a different room to use more efficient ventilation grids if any, | ||
| Line 37: | Line 34: | ||
* Use air conditioning systems or air forced cooling with filters installed in air inlet to restrict entry of pollution and dust. | * Use air conditioning systems or air forced cooling with filters installed in air inlet to restrict entry of pollution and dust. | ||
* Regularly clean all traces of pollution from metal and insulating parts. | * Regularly clean all traces of pollution from metal and insulating parts. | ||
* Instead of using AIS equipment | * Instead of using AIS equipment {{FigRef|B36}}, use equipment that is insensitive to the environment such as GIS or 2SIS type (see {{FigRef|B37}}). | ||
{{FigImage|PB116698|jpg|B36|SM6 Modular Unit}} | |||
{{FigImage|PB116699|jpg|B37|PREMSET. Shielded Solid Insulated MV equipment}} | |||
Latest revision as of 09:48, 22 June 2022
The purpose of this chapter is to provide general guidelines on how to avoid or greatly reduce MV equipment degradation on sites exposed to humidity and pollution.
Normal service conditions for indoor MV equipment
All MV equipment are intented to be used in the normal services conditions as defined in IEC 62271-1 standard "Common specifications for high-voltage switchgear and controlgear".
For instance, regarding humidity, the standard mentions:
- The average value of the relative humidity, measured over a period of 24 h does not exceed 95 %;
- The average value of the water vapour pressure, over a period of 24 h does not exceed 2.2 kPa;
- The average value of the relative humidity, over a period of one month does not exceed 90 %;
- The average value of water vapour pressure, over a period of one month does not exceed 1.8 kPa.
As indicated in the standard, condensation may occasionally occur even under normal conditions. Either switchgear designed for such conditions shall be used and/or special measures concerning the substation premises can be implemented to prevent condensation, such as suitable ventilation and heating of the station.
Use under severe conditions
Under certain severe conditions concerning humidity and pollution, largely beyond the normal conditions of use mentioned above, electrical equipment can be subject to damage by rapid corrosion of metal parts and surface degradation of insulating parts. Examples of suitable measures of protection against condensation and pollution are listed below.
Remedial measures for condensation problems
- Carefully design or adapt substation ventilation.
- Avoid temperature variations.
- Eliminate sources of humidity in the substation environment.
- Install an Heating, Ventilation, Air Conditioning unit (HVAC)
- Make sure cabling is in accordance with applicable rules.
Remedial measures for pollution problems
- Equip substation ventilation openings with chevron-type baffles to reduce entry of dust and pollution especially when the transformer is installed in the same room with switchgears or controlgears.
- Install the transformer in a different room to use more efficient ventilation grids if any,
- Keep substation ventilation to the minimum required for evacuation of transformer heat to reduce entry of pollution and dust
- Use MV cubicles with a sufficiently high degree of protection (IP)
- Use air conditioning systems or air forced cooling with filters installed in air inlet to restrict entry of pollution and dust.
- Regularly clean all traces of pollution from metal and insulating parts.
- Instead of using AIS equipment Fig. B36, use equipment that is insensitive to the environment such as GIS or 2SIS type (see Fig. B37).
Fig. B36 – SM6 Modular Unit
Fig. B37 – PREMSET. Shielded Solid Insulated MV equipment
