In photovoltaic power generation, energy storage systems, and industrial automation systems, inverters are core devices for converting DC to AC. Different usage scenarios and environmental conditions have different requirements for the protection capabilities of inverters. Reasonable selection of the protection level of the inverter can not only ensure the stable operation of the equipment, but also extend its service life. This article explores in depth what is the basis for selecting the protection level of the inverter? Help you choose the right inverter.

1. Basic concepts of protection level

1.1 Definition and structure of IP code

IP (Ingress Protection) code is a standard (IEC 60529) developed by the International Electrotechnical Commission (IEC) to define the protection level of electrical equipment housing against solid foreign objects and liquid intrusion. IP code usually consists of the letters "IP" followed by two digits:

First digit: indicates the protection level against solid foreign objects (including dust), ranging from 0-6

Second digit: indicates the protection level against liquids (mainly water), ranging from 0-9

For example, IP65 means "completely dustproof" and "protected against low-pressure water spray".

1.2 Common protection levels of inverters and their meanings

Common protection levels of inverters include:

IP21: prevents the entry of solid foreign objects with a diameter greater than 12.5mm, can only cope with slight dripping, and cannot prevent rain splashing or high-pressure water mist. Suitable for dry and clean indoor environments.

IP65: Completely dustproof and prevent harmful effects of water spray. Suitable for outdoor installation but need to avoid direct rain.

IP66: Completely dustproof and protected against harmful effects of strong water jets. Withstands high pressure water jet cleaning.

IP67: Completely dustproof and can withstand short-term immersion in water (15cm-1m, 30 minutes). Suitable for environments where temporary immersion in water is possible.

IP68: Completely dustproof and can withstand continuous immersion in water (more than 1m, continuous immersion). Suitable for underwater or high humidity environments.

2. Impact of environmental factors

2.1 Climate conditions

Desert areas: Summer temperatures can reach above 50°C, and the internal components of the inverter are prone to accelerated aging due to overheating. At the same time, the high temperature environment is dry and the sand and dust particles are active, so the inverter needs to have good heat dissipation and dustproof performance. Dustproof should be given priority, and the IP6X series is required.

Humid areas such as coastal areas, tropical rainforests, and cold climates: The inverter must have sufficient waterproof capabilities to prevent rain or snow from entering. High humidity may cause the circuit board to become damp and short-circuit, so a higher waterproof protection design must be selected, such as the IPX5 series or above.

2.2 Special environment

High altitude area: Altitude will affect the heat dissipation and insulation performance of the inverter. As the altitude increases, the atmospheric pressure decreases, the air density decreases, the heat dissipation is difficult, and the temperature inside the equipment is easy to rise. At the same time, the low pressure environment will reduce the insulation performance of the electrical clearance and creepage distance, and increase the risk of electrical failure. Therefore, the inverters used in high altitude areas, in addition to considering heat dissipation, also need to improve the protection level, enhance electrical insulation and sealing.

Industrial area: In some special geographical areas, such as around chemical plants and coastal salt spray environments, there are a lot of corrosive gases or particles in the air. Sulfur dioxide and chlorine emitted by chemical plants, as well as coastal salt spray, will corrode the metal casing and internal components of the inverter. Inverters in these environments must not only be well sealed to prevent the intrusion of corrosive gases, but also use anti-corrosion coatings or special material casings, and the protection level is usually required to reach IP66 or above.

3. Requirements for application scenarios

3.1 Industrial applications

The environment of industrial production workshops is complex, and inverters are often threatened by solid particles such as dust and metal shavings. For example, metal shavings in machining workshops and cotton wool in textile factories, once entering the inverter, may cause short circuits in circuit boards or wear of mechanical parts. Therefore, inverters for factory production lines need to be designed with a high dustproof grade, such as IP65 or IP66. At the same time, there may be liquids such as oil, water vapor, etc. in the workshop, and the inverter must also have a certain waterproof capability.

The mining environment is harsh, and inverters face challenges of high dust, high vibration, and high impact. The dust concentration in mines is extremely high, and the dustproof performance requirements are extremely high, usually reaching IP67 or even IP68. In addition, the vibration and impact caused by the frequent start and stop of mining equipment require the inverter housing to be sturdy and able to withstand mechanical external forces.

3.2 Civil and commercial applications

Household photovoltaic inverters are generally divided into indoor and outdoor installations. If installed in a dry and clean machine room, basement, warehouse, etc., IP20-IP21 is sufficient. If installed outdoors and considering that home users lack professional maintenance capabilities, choosing an inverter with a higher protection level can reduce failure and maintenance frequency. Inverters with an IP65 protection level can not only prevent rain, sand and dust, but also meet daily outdoor use needs.

Inverters in commercial buildings, such as equipment rooms or basements in shopping malls and office buildings, have a relatively stable environment, but there may be problems with moisture and condensation. When air conditioning is used in summer, the temperature difference between indoors and outdoors is prone to condensation, so it is necessary to choose an inverter with a certain waterproof and moisture-proof ability, and the protection level is generally IP54 or IP55. The inverters in data centers have extremely high reliability requirements and need to ensure good heat dissipation while preventing dust.

3.3 Electric vehicle applications

In the field of transportation, such as electric vehicles and electric buses, the working environment of the inverter is complex and changeable. The vibration and impact during vehicle driving, the temperature and humidity changes in the confined space, and the risk of splashing water during driving on rainy days all require the on-board inverter to have a higher protection level, such as IP67, and good seismic performance.

3.4 Offshore applications

In offshore wind power, floating photovoltaics, and ship applications, the inverter is in a marine environment with high humidity, high salt fog, and strong wind for a long time. Salt fog is extremely corrosive to equipment. The protection level of offshore wind power inverters usually needs to reach IP68, and special anti-corrosion materials and coatings are used. Inverters on ships also face problems of humidity, vibration, and salt fog, and the space is limited, so the protection and heat dissipation performance are very high.

4. Consideration of the characteristics of the equipment itself

The inverter will generate a lot of heat during operation, and the heat dissipation method affects the selection of protection level. For inverters with natural heat dissipation, the protection level may be compromised to ensure ventilation, and IP54 or IP55 is generally selected. For inverters with forced air cooling or liquid cooling, the protection level can be appropriately increased, such as IP65 or IP66, because the heat dissipation system can effectively dissipate heat in a closed environment.

From the perspective of electrical safety, a high-protection-level housing can prevent people from getting electric shocks and prevent conductive materials from entering and causing short circuits. In crowded or non-professional operating places, such as shopping malls and schools, high-protection-level inverters should be given priority. In addition, the installation method of the inverter (wall-mounted, floor-standing, embedded, etc.) also affects the selection of protection level. Wall-mounted inverters are exposed to the outside and require higher protection; embedded environments are stable and can appropriately reduce requirements. At the same time, it is also necessary to balance protection performance and maintenance convenience to avoid high protection levels increasing maintenance difficulty and cost.

5. Trade-off of cost factors

As the protection level increases, the manufacturing cost of the inverter increases accordingly. Equipment with high protection levels requires a more robust housing, precision sealing technology, and special protection design, which leads to higher prices. For example, an inverter with IP68 protection level may cost 30% - 50% more than an inverter with IP54 protection level. Projects with limited budgets may choose a lower protection level while meeting basic requirements, but this will increase the cost of later failures and maintenance.

Although the initial purchase cost of inverters with high protection levels is high, in the long run, their maintenance costs and failure rates are low. Inverters with low protection levels are easily damaged in harsh environments. Frequent repairs not only increase costs, but may also cause equipment downtime, resulting in greater economic losses. Therefore, when choosing a protection level, it is necessary to comprehensively consider the initial purchase and long-term operation and maintenance costs, and conduct a cost-benefit analysis.

6.Conclusion

The selection of inverter protection level is a comprehensive process that considers environmental factors, application scenarios, equipment characteristics, and costs. Different environments and applications have different requirements for protection capabilities. The equipment's own heat dissipation, safety, installation and maintenance characteristics also affect the decision, and cost-effectiveness must also be balanced. Only by comprehensively considering these factors can we select the appropriate protection level for the inverter, ensure its stable and reliable operation, and maximize its performance and benefits.