RW 12-15 Jet Drop Fuse

Summary

Drop-down fuse is one of the most commonly used short-circuit protection switches for branch lines and distribution transformers of 10 kV distribution lines. It has the characteristics of economy, easy operation and strong adaptability to outdoor environment. It is widely used in the primary side of 10 kV distribution lines and distribution transformers for protection and switching operation of equipment.

It is installed on the branch line of 10kV distribution line, which can reduce the blackout scope. Because it has a high-voltage drop fuse obvious break point and has the function of disconnector, it creates a safe working environment for the overhaul section lines and equipment, and increases the security sense of the overhaul personnel. Installed on distribution transformer, it can be used as the main protection of distribution transformer, so it is widely used in 10 kV distribution line and distribution transformer.

Installation Notes

(1) When installing, the melt should be tightened (so that the melt is subject to about 24.5N tension), otherwise it is easy to cause contact heat.

(2) The fuse shall be firmly and reliably mounted on the crossbar (frame) without any shaking or shaking.

(3) The inclination angle of the fuse pipe should be 25 +2, so that the fuse pipe can fall rapidly by its own weight when the melt is fused.

(4) The fuse should be installed on a cross-arm (frame) with a vertical distance of not less than 4m from the ground. If it is installed above the distribution transformer, it should keep a horizontal distance of more than 0.5m from the outermost contour boundary of the distribution transformer in case of other accidents caused by the falling of the fuse pipe.

(5) The length of the fuse pipe should be adjusted moderately. It is required that the duck-billed tongue can hold up more than two-thirds of the length of the contact after closing the fuse pipe, so as to avoid the mistake of falling by itself during operation, and that the fuse pipe should not hold the duck-billed to prevent the fuse pipe from falling in time after melting.

(6) The melt used must be the standard product of the regular manufacturer and have certain mechanical strength. Generally, the melt must be able to withstand at least 147N of tensile force.

(7) 10kV drop fuse is installed outdoors, and the distance between phases is more than 70cm.

Operation of drop fuse

In general, it is not allowed to operate drop fuses with loads, but only to operate no-load equipment (lines). However, the branch lines of 10kV distribution lines and distribution transformers with rated capacity less than 200kVA in the rural power network are allowed to operate with load according to the following requirements:

(1) The operation shall be carried out by two persons (one person to monitor and one person to operate), but they must wear qualified insulating gloves, insulating boots and goggles, operate with qualified insulating rods matching the voltage level, and prohibit the operation under lightning or heavy rain.

(2) When pulling the brake, it is generally stipulated that the middle phase is pulled first, then the leeward side phase is pulled, and finally the windward side phase is pulled. This is because the distribution transformer is changed from three-phase operation to two-phase operation, and the arc spark generated when the intermediate phase is broken is the smallest, so that the short circuit between phases is not caused. Secondly, pull off the leeward side phase, because the middle phase has been pulled apart, and the distance between the leeward side phase and the windward side phase has doubled. Even if there is an overvoltage, the possibility of inter-phase short circuit is very small. Finally, when the windward side phase is cut off, only the capacitive current to the ground will produce a slight spark.

(3) On the contrary, when closing, the operation sequence is opposite. First, the windward side phase is closed, then the leeward side phase is closed, and finally the intermediate phase is closed.

(4) The operation of molten pipe is a frequent project. Unnoticed will cause contact burns, resulting in poor contact, overheating of contacts, annealing of springs, making contact more harmful, forming a vicious circle. Therefore, when pulling and closing the fused pipe, we should exert moderate force. After closing, we should carefully check that the duck-billed tongue can tightly fasten the length of the tongue by more than two-thirds. We can use the pull brake rod to hook up the duck-billed and press down a few times, then gently try to pull, and check whether the duck-billed tongue is closed properly. When closing, it is not in place or firmly closed, and the static contact pressure on the fuse is insufficient. It is very easy to cause contact burns or the fuse pipe drops by itself.