use

Fuses are active components mainly used for overload and short-circuit protection in low-voltage distribution networks and control lines. It can also be used for overload protection of cable conductors and protection of power electronic components. Structural features, the fuse consists of a fuse base and a fuse (fuse core).

simple principle

When the fuse is connected in series in the circuit, when the circuit is overloaded or short-circuited, the temperature of the fuse rises to the melting point of the fuse (or fuse sheet), and the fuse melts rapidly, thereby cutting off the circuit.

In order to effectively control the melting point at the thinnest point of the fusible line, solder beads are often soldered here. Using the metallurgical effect formed by the molten tin bead and the copper fuse wire, the melting point can be lowered, and the controllable fusing temperature can be obtained, thereby realizing the anti-DC fuse time-limited line protection characteristic of the fuse core blown.

In order to effectively eliminate metal vapor and explosive gas, the fuse body is filled with quartz sand filler to effectively extinguish the arc. Sometimes closed tubular fuse bodies without fillers are used to extinguish the arc by utilizing the gas pressure generated at high temperatures. Fuses have high breaking capacity and reliability, easy maintenance and relatively low prices, so they are widely used in low-voltage distribution networks.

 The working principle of photovoltaic DC:

Metal conductors are connected in series in a circuit as a melt, and when an overload or short-circuit current passes through the melt, it melts due to its own heat, thereby breaking the circuit. The fuse has a simple structure and is easy to use, and is widely used as a protection device in power systems, various electrical equipment and household appliances.

DC fuses If it is not certain that the part will not be adversely affected by temperature and blocking force, the following tests shall be carried out.

1. Test the setup.

Install the simulated fuse link on the PV DC fuse base and hang it on the measuring device. The fixing method of the simulated fuse link of the photovoltaic DC fuse base (such as using a bayonet) has no obvious effect on heat dissipation. Conductor load area and rated value See Table 10 in GB13539.1-2002 for related current. The length of the wires outside the oven is at least 1m. The measuring device should be installed in an oven with a volume of at least 50L or under a heating mantle. Note the housing of the measuring device and the connecting wires. During the test cycle with and without test current, the oven temperature should be maintained at (80+DC fuse 5) ℃, and the temperature should be measured at a horizontal distance of 150mm from the center point of the simulated fuse-correlation.

2 Test method.

After raising the furnace temperature to (80+5) ℃ for 2 hours, the simulated fuse is connected to 160% rated current for 2 hours, and the current tolerance is ±2%. Tests can be performed at reduced voltages. After 3 min of current, the pulling force Fmax is smoothly applied to the simulated fuse link. The pulling force lasts 15s.

3 Judgment of test results.

After testing, the displacement of the contacts of the base of the photovoltaic DC fuse should not affect the continued use of the base of the photovoltaic DC fuse. The dimensions should be measured after removing the analog fuse. The insulation of the PV DC fuse base should not crack or show any cracks.