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Although the pv inverter only accounts for 10% of the cost of the whole pv system, it is the core component of the whole system and directly affects the power generation income of users. Today we talk about the safety of the inverter

About the safety of the inverter

  • Xindun
  • December 12, 2020

Although the pv inverter only accounts for 10% of the cost of the whole pv system, it is the core component of the whole system and directly affects the power generation income of users. How to evaluate a inverter is good or bad, there are many performance indicators, such as efficiency, reliability, network interface friendliness, and the author believes that no matter how the inverter manufacturers advertise, the safety performance of the inverter must come first. Below is a photovoltaic roof project spread on the network of domestic family photos of the inverter is on fire, the cause of the fire is unknown, but we can guess, unsafe products surely will endanger the life property safety of the user, therefore, when we choose a brand of inverter, the first step is to consider the security performance of the inverter.


About the safety of the inverter


So, what kind of inverter is a safe inverter? Although, as an electrical product, there is no 100 percent safe inverter, but a good product must have considered the potential risks at the beginning of the design and minimized the risks. This article will outline some of the possible security risks of inverters for readers to make decisions when selecting inverters.


Electric shock and energy hazards

Any voltage other than the safe voltage may lead to electric shock hazard. The limit of the safe voltage is as follows:


Safety voltage

Effective value of ac voltage

Ac voltage peak

Dc voltage

Dry environment

25

35.4

60

Damp environment

16

22.6

35


The design of electric shock risk should pay attention to the following points:

1. The inverter is basically the equipment of protection class I. It is protected by basic insulation and chassis grounding.

2. The selection of safe insulation materials shall be determined according to the working voltage and working environment;

3. The electrical clearance and creepage distance shall be satisfied in accordance with the standard requirements, and the clearance shall not be reduced during transportation and installation;

4. Energy risk means that the energy obtained after 60 seconds is 240VA or more than 2V, and the stored energy is greater than 20J;

5. The following points should be noted in the design of energy hazards:

The operator can touch the area without any energy hazard, such as the ports of the inverter connector.

If there is an inevitable energy hazard in the accessible area of the maintainer, there should be a corresponding warning sign and the safe operation method should be explained in the manual.


Fire and heat hazards

Fire risk refers to the spontaneous combustion of products and their extension to the surrounding environment, resulting in great human injury and property damage. As you know, cell phones burn themselves.


Two ways to reduce fire risk:

Use fireproof enclosures and select and use materials that reduce natural or combustible materials;

Without the use of a fireproof case, a single fault test is conducted on all components to verify that there is no spontaneous combustion or ignition. Due to the influence of heat, the insulation grade decreases or the performance of safety components decreases. The production of flammable gas or liquid due to the influence of heat.


The design of thermal hazards should consider the following points:

Reasonable layout, good design, so that heating components within a reasonable and safe temperature range;

Considering the component decay factor in thermal condition for a long time;

Limiting the temperature of the contact surface;

Limit the temperature of the installation surface and the installation surface shall not exceed 90 degrees.


Mechanical danger

Mechanical hazards include personal injury caused by sharp edges or corners, moving parts, projectiles and so on, as well as personal injury and property loss caused by the stability of the product.

The following points should be noted in the design of mechanical hazards:

The moving parts shall be sealed or protected to prevent personal contact, such as fans.

The high-power inverter installed in the ground shall consider the stability of tilting 10 degrees in either direction in the normal installation position, and the door or other detachable device shall be at the most unfavorable position.

The small and medium power inverter installed in the wall type should consider its hanger structure can withstand the force of 4 times the weight of the product without any deformation or damage.


Danger of noise

Anything that turns a person off or doesn\'t require a sound can be called noise. If the noise measured one meter away from the inverter is greater than 80 decibels, the noise risk is considered.

For small and medium power, although there is no noise risk, since the use environment is the residential area, the noise risk should be reduced as low as possible, without bringing any noise that affects people\'s life.

For high-power inverter, if there is noise risk, the risk should be identified and the guidance method should be given to reduce noise.


Chemical hazard

Chemical hazard means that the material used by the inverter contains chemical harmful substances, or it will produce toxic chemicals or steam during operation. When selecting the inverter, the harmful substances and content of the product should be understood by the manufacturer or distributor. If the product is not satisfied with the national safety standard, the product should not be selected.


Danger of radiation

Radiation hazards include nuclear radiation, ionizing radiation, and electromagnetic radiation. The radiation hazard in inverter is mainly electromagnetic radiation. Electromagnetic radiation should be designed to ensure that the radiation of the inverter meets the requirements of electromagnetic compatibility standard, and does not affect any other equipment of the user. It should be noted that the inverter should be tested and verified under various harsh conditions.