Problems existing in the use of photovoltaic combiner boxes
1. Security issues
1) Arc in the process of fuse insertion
The plastic shell type fuse consists of a seat and a handle. The two ends of the seat are provided with metal sockets. The sockets cooperate with the fuse body pierced in the middle of the handle to achieve the functional requirements of the fuse.
In the actual field, it is very common to pull this structure by mistake: when the fuse is pulled, the handle cannot disconnect the two contact points of the fuse at the same time, and the DC voltage in the loop can be as high as 1000V, which can burn the fuse holder and burn the hands. Equipment and personal safety accidents will occur.
There is a fuse socket directly welded on the PCB board: the safety protection is too poor. In the grounding system, if the person touches the high voltage of DC1000V, it will create a circuit with the ground, which will endanger life safety; people touching the positive and negative electrodes at the same time will also endanger life safety.
To replace the fuse, it must be operated without power. The final pressure of the fuse and the socket, and the welding firmness of the fuse and the PCB puller, all determine the higher temperature rise of the box and the generation of arcs. If an arc is generated, the entire PCB will be burned, and eventually lead to The entire combiner box burned out.
2) Arc generated after virtual connection between cable and terminal
In the existing combiner box, the connection between devices is mostly connected by wires, and there are nearly 100 joints in one combiner.
Since the wire is a multi-strand flexible wire, after a long-term operation, the copper wire may be permanently deformed under long-term pressure, so that the pressure is reduced, and in severe cases, high temperature will occur, until an arc burns out the device and the combiner box.
3) Creepage distance problem
In the photovoltaic system, the creepage distance is related to the voltage. According to the American UL standard, considering the damage of the box body and the same internal and external environment, it belongs to the outdoor working electrical appliances. It is stipulated that the creepage distance of the electrical appliances used in the photovoltaic DC1000V system should be greater than 54mm. Otherwise, in the case of condensation and dirt, discharge will occur, causing a short-circuit accident between the positive and negative electrodes, and the positive and negative electrodes are connected to the ground at the same time.
4) Electrical clearance problem
The electrical clearance is related to the voltage. According to the UL standard of the United States, considering the damage of the box body, the internal and external environment is the same, and it belongs to the electrical appliances for outdoor work. The discharge will cause air discharge or short circuit between the positive and negative electrodes, and between the positive and negative electrodes to the ground at the same time.
Abundant Fuses, product line covers all relevant areas of new energy vehicles (Pack, PDU, BDU, Electric control, Motor, MSD, Low voltage wiring harness), Charging system and the Charging Module, Photovoltaic PV Solar junction box, photovoltaic inverter, UPS power supply, 5G Communication power supply, BS UK plug, Electrical Home Appliances Control Panel, Lighting drive Power Supply and so on.
If you have any enquiry about quotation or cooperation, please feel free to email us at holly@delfuse.com