Photovoltaic connector -- small device plays a big role

27-03-2019

Photovoltaic power connector -- small device large role photovoltaic connector, also known as MC connector, in the photovoltaic system, the connector proportion is very small, but a lot of links need to be used, such as junction box, junction box, components and inverter cable connection between the need.Many construction workers do not have enough understanding of connectors, and there are many power station failures caused by connector problems. In another report "review and analysis of factors affecting photovoltaic power generation" released by NBC in July 2016, among the TOP20 influencing factors of power station, the power generation loss caused by connector damage or burn out ranked the second.


Photovoltaic connector


In addition to the quality of the connector itself, another important reason that led to the burning of the photovoltaic connector was that the construction was not done well, resulting in the virtual connection of the connector, which caused the dc side arc drawing and then caused the fire.Problems caused by connectors include: increased contact resistance, heating of connectors, shortened service life, burning of connectors, power failure of clusters, failure of junction boxes and leakage of components, etc., which result in system failure and affect power generation efficiency.


A few days ago, a customer said that he had recently made a 25KW inverter with abnormal working status and low power generation. He asked for an analysis of the reason. Therefore, he carefully checked the monitoring account of the customer and found that there was a very low MPPT voltage, which was obviously abnormal.


power connector


This 25kw inverter has two MPPT channels, one is connected with two strings, the other with three strings, connected with 320 crystal silicon components, the connection is 18 strings of 3 and +16 strings of 2 and.


As can be seen from the current size of the monitoring interface, PV2 is connected with 18 strings of 3, while PV1 is connected with 16 strings of 2.The voltage of PV1 is 611.5v, while that of PV2 should be around 688V under normal circumstances. However, the actual voltage of PV2 is only 315.9v, which is close to 372V. Therefore, it is considered that there is something wrong with the component's side wiring (part of which may be shorted), so it is necessary to investigate the cause on site.


The after-sales service engineer found on the site that the wiring terminal of the lower end of the inverter had burned out. After careful investigation on the site, it was determined that it was the non-standard compression joint (the joint in the yellow ring) during the construction, the joint was not done well, and the virtual connection ignited and caused the arc, causing the cable to burn down and the inverter terminal burned down.


Photovoltaic connector


In the whole photovoltaic system, the dc side voltage is usually as high as 600-1000v. Once the photovoltaic module joint is loose and the contact is bad, the dc arc drawing phenomenon is easily caused.Dc arc leads to contact part of the temperature rise sharply, constant arc will produce 1000-3000 ℃ high temperature, and accompanied by high temperature carbonization surrounding devices.Fuse insurance, cable, heavy equipment to cause fire.


The non-standard bonding of photovoltaic connectors is mainly due to the gap between field tools and operating experience, resulting in poor bonding quality. The main problem is that the cable copper wire is bent, part of the copper wire is not pressed in, and the bonding part is the cable insulation layer.


After the series is finished, connect it to PV terminal of the inverter, and try to use PV connector of the original manufacturer of the inverter, because this is paired with PV terminal above the inverter. If pressed correctly, it can be well matched, with low contact resistance, low heat output, lower temperature and more reliable and safe operation.


power connector

When it comes to the bonding process, we also need to pay attention to the stripping link, the standard for the number of copper wire cut in the stripping is strictly regulated.If more copper wire cut will affect the pressure and flow quality, resulting in a higher temperature rise.


For this problem, it is suggested that qualified installers can choose professional tools, give corresponding training to on-site installers, and set up a sampling inspection mechanism.


Photovoltaic connector


Conclusion:

enough attention to. In the process of product selection and construction, the following points should be paid attention to:

1. Adopt domestic and foreign famous brand products with reliable quality.

2. Products from different manufacturers cannot be mixed together and may not match.

3. Professional wire stripping pliers and crimping pliers are used. Unprofessional tools cause poor crimping.For example, part of the copper wire is cut, some copper wire is not pressed in, mistakenly pressed to the insulation layer, the pressure is too small or too big.

4. After the connectors and cables are connected, they should be tested. Under normal circumstances, the resistance is zero and the hands cannot be broken by pulling hard.


NBC Electronic Technological Co.,Ltd(NBC),founded in 2006our aim is: innovate product category,control first-class quality.We have wide range of space in fast connectors ,industrial connectors,power connectors,battery connectors,charging connectors,electrical connectors,high current connector ,Anderson power products,APP connectors,module connectors,battery connectors and so on .In the year 2019,we had go abroad and compete for the international market.

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