Fuse indicating transmission device

 INSTALLATION SIZE AND USE DEBUGGING : 

• The device is installed in any direction after the insulation distance is attached, and its size is shown in Picture 1. For example, the impactor of the fuse is a spring type, which can move the target head by 10mm. Outside the axis (as shown in Picture 2), if the impactor is a gunpowder type, the target head can be moved to the axis of 3mm from the impactor, and the distance between the push ring and the micro rod can be adjusted 5mm.

 FACTORS TO BE CONSIDERED WHEN CHOOSING

1. For the fuse, the installation environment conditions used are a very important factor, which not only affects the performance of the fuse, but also affects its ability to safely break faults. Therefore, it must be properly considered.
2. A common installation method is to install the fuse in a three-phase enclosed box, At this time, the rated current of the fuse must be reduced by 15%. However, when the rated current of the fuse is less than 20A, derating is not considered. It is because the fuse with small rated current has less heat and low temperature rise, and the enclosed environment has little effect on it. Another installation method is to enclose a single fuse in an insulating resin cast cylinder. In this case, the rated current of the fuse should be reduced by 25% to ensure that the fuse will not be overheated and damaged. For the rated current For fuses below 20A, derating can still be ignored. According to the provisions of the IEC standard, the fuse can work normally in the range of ambient temperature between -25°C and 40°C. When the temperature is lower than -25°C, the mechanical properties of the fuse will be affected. When the temperature is higher than 40°C, the rated current of the fuse should be reduced by 1% for every increase of 1°C. For three-phase installation in an unenclosed cabinet, due to the mutual interference between the temperature rise of the three-phase fuses, the rated current of the fuse should generally be reduced by 10%, and the fuse below the rated current of 20A can still be ignored. For fuses with low rated current levels below 10A, the melt is prone to ageing due to the long-term corona discharge on the melt. Therefore, the fuse should be avoided as far as possible from the grounded metal frame.
3. In order to increase the current rating of the fuse, users often use two or three fuses in parallel. At this time, the mutual influence factors of temperature should also be considered. Generally, the fuse can be derated by 10% to 20%. At this time, the fuse cut-off characteristics and 12t characteristics all follow the following principles. Ip total= nx (Ip 1 when the expected current of a single fuse is Ip/n) Among them, Ip is the peak value of interception after parallel connection Ip-expected current effective value n-the number of fuse in parallel Ip1 a single fuse cut-off peak value I't total = n'x (I't value when the expected current of a single fuse is I,/n)
4. It should be noted that the fuse must not be simply used in series in a higher voltage circuit.

INSTALLATION AND REPLACEMENT 

1. Before installation, check whether the appearance of the fuse is completo, good, and clean. If the fuse has been dropped or violently shaken, check its resistance.
2. When installing, pay attention to the direction of the striker indicated on the fuse, so that it can be installed in the correct position, and then lock the spring ring and bolt on the base to prevent loose contact.
3. In a three-phase system, when a fuse is activated, generally all three fuses should be replaced unless it can be verified that only one fuse has passed the short-circuit current. This is mainly because although the other two fuses are not blown, they may have been severely damaged and are close to damage.
4. Be very careful when replacing the fuse, because the current-limiting fuse has a safety range during operation, and it cannot guarantee that every fault condition is within its safety range, such as the tripping failure of the switchgear, or the fuse Operate below its minimum breaking current, etc. For safety reasons, you must wait at least minutes after the fuse is activated and the circuit is isolated from other electrical e you can replace it. Make sure that the fuse is replaced when it is not energized. appliances before y
5. In the general power system, if the selection is appropriate, the fuse should rarely act. If this is not the case, it is likely that the system is selected improperly the fuse is calculated incorrectly, and further inspections should be done. And calculations.
6. For the fuse in normal operation, when the equipment is regularly checked and repaired, the change in the internal resistance of the fuse can be measured to determine whether it is aging, and the internal resistance should be within 10% of the soil. When it exceeds the range, it is recommended to replace the fuse to avoid malfunction.