SU113776A1 - Protection of three-phase electrical installations - Google Patents

Description

A known type of protection is three-phase electrical installations with three fuses, the blown one of which causes the opening of the circuits of the remaining phases by firing the fuse-links of these phases.

The peculiarity of the proposed protection lies in the fact that the middle part of the fusible insert is placed in a metal case electrically connected to one of the neighboring phases through its fusible insert. This ensures an increase in the reliability of the protection operation and an increase in the power of the fuse.

FIG. 1 shows the proposed fuse section; in fig. 2 and 3 embodiments of the electric circuit of the proposed protection.

Ko) riyc fuse 1 is a piece of metal tube - ;, which is closed at both ends of the N 1 skirt 2 of fire and moisture resistant (X) ;;, -; electrically insulating material. A fused insert 3 passes through the plug, the ends of which are clamped by or sealed with metal caps JMi 4.

Preventer is inserted into

three-jawed jaws so that two of them are electrically connected to the ends of the fuse-link, and a third, medium-sized, with a metal fuse box.

As is well known, the fusible link fuse blows out always in the middle of its length. The flames, vapors, and the dissociated meta-tl arising from the burnout of a hot-melt insert cause brief terrestrial ionization of the air gap between the insert 3 and the body / guard, resulting in a short circuit. In case of a fuse of the fuse insert of the phase L fuse, due to the presence of an electrical connection between the metal / this clause of the fuse and phase B through its fuse plug 3, an interphase short circuit occurs (Fig. 2). This entails the combustion of the fuse-link fuse of phase B, and then the same way the combustion of the fuse-link fuse of phase B.

Thus, a three-phase sanding load (e.g., an electrical wiring) is provided from overload and from operation on two phases, as well as from the supply mains from short-circuit currents.

In the version of the protection scheme shown in phi1. 3, the insertion of inserts of all three phases occurs only when the insertion of phase A is burned, while the insertion of phase B or C burns, the inserts of these phases are ignited. and the insertion of phase L does not burn out.

Since the motor cannot work on one phase, it stops.

Ire d m from and 3 about b e and e and

Zap (three-phase electrical installation with three fusible preservatives, in which the burnout of one of the fusible inserts causes) closing of the circuit left) protect the reliability and increase the discontinuity of the MOUTURE; 1. The middle part of the fusible insert is placed in a metal case, electrically connected (to the odpon of the adjacent phases through its low pressure insert.

 FIG. 2 WITH

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