When replacing drop fuses, load operation is generally not allowed, only no-load equipment (line) is allowed to operate, do not expand or reduce the rated voltage and rated current level of drop fuses, only remove the same volume and the same working voltage level, otherwise it will lose fuse maintenance.
Specific precautions for replacing a fall fuse are as follows:
1. The operation shall be carried out by two persons (one monitoring person, one operating person), but the wearer must wear qualified insulation gloves, insulation boots, and protective glasses, and use qualified insulation rods with the corresponding voltage level. The operation shall not be carried out in lightning or heavy rain.
2. When pulling the brake operation, it is generally required to pull the middle phase first, then the leeward side phase, and then the windward side phase. This is because the distribution transformer is changed from three-phase operation to two-phase operation, and the arc spark generated by intermediate phase breaking is minimal, which will not cause short circuit between phases. Second, pull off the leeward side phase, because the middle phase has been opened, the distance between the leeward side phase and the windward side phase has doubled, even if the overvoltage is generated, it is unlikely to cause short circuit between phases. When the windward phase is then pulled off, only the capacitance current to the ground produces a very slight spark.
3. When closing, the operation sequence is opposite. First close the windward side phase, then close the lee side phase, and then close the middle phase.
4. Drop type fuse fuse replacement operation is a frequent project, if not paid attention to, will cause contact burns, resulting in poor contact, overheating contact, spring annealing, make contact contact worse, forming a vicious cycle.
Therefore, pull, weld tube, should be moderate force. Once closed, carefully check that the duck's beak and tongue can hold tightly more than two-thirds of the length of the tongue. You can hook the duck's beak with a drawbar, press it down a few times, and then gently try to pull it to check that it fits. When closing is not in place or not firm, the static contact pressure on the fall-type fuse is insufficient, which is easy to cause the contact burn or the fuse to fall down by itself.
