JPS5921142B2 - Dashpot type overcurrent detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION As shown in FIG. 1, the conventional dashpot type overcurrent detection device connects the open end of a bottomed cylinder a made of a non-magnetic metal with a cover made of a magnetic material. When oil is sealed in the cylinder a in an airtight manner, and a plunger C made of a magnetic material is slidably housed in the cylinder a and the lid is attached, a spring d is inserted between the plungers C. a yoke e that is compressed and has one end fixed to the outer circumferential shell of the intermediate portion of the cylinder a;
The lower surface of the free end of the rotary iron piece f, whose base end is pivotally supported at the other end, faces the upper surface of the lid body, and acts in a direction to pull the lower surface of the free end of the movable iron piece f away from the lid body. A return spring g is elastically loaded, and a coil h is wound around the outer circumferential body above the fixed part of the cylinder a to the yoke e, and the coil h is inserted and connected in series to the distribution line. When a short-circuit current flows through the wire, the magnetic flux generated by the current flowing through the coil h flows through the magnetic path i.
The magnetic flux causes the lower surface of the free end of the movable iron piece f to come into contact with and be attracted to the upper surface of the lid, and a short-circuit current can be detected by the movement of the movable iron piece f.

However, a short circuit current flows through the distribution line, that is, coil h,
As a result, when the magnetic flux generated in the magnetic path i increases in force H, the magnetic flux in the magnetic path i lags behind the short-circuit current because an overcurrent flows in the cylinder K, and at the same time as the short-circuit current flows, the lower surface of the free end of the movable iron piece f There was a drawback that short-circuit current could not be detected instantaneously because it was not attracted to the top surface of the lid.

The present invention eliminates the above-mentioned drawbacks of the conventional technology, and the embodiments of the present invention will be described below with reference to the drawings.
1 is a bottomed cylinder made of non-magnetic metal with an opening at the top, and the top opening is hermetically closed with a lid 2 made of a magnetic material, so that silicone oil or other oil is sealed inside the cylinder 1.

3 is a plunger made of a magnetic material that is slidably housed in the cylinder 1; 5 is a yoke plate whose base end is fixed to the outer peripheral body of the intermediate portion of the cylinder 1; and 6 is a plunger whose base end is pivoted to the tip of the yoke plate 5. It is a supporting movable iron piece, and the lower surface of its free end faces the upper surface of the lid 2 with a gap therebetween.

7 is a return spring that acts in a direction to separate the lower surface of the free end of the movable iron piece 6 from the upper surface of the lid body 2; 8 is the yoke plate 5 of the cylinder 1;
This is a coil that is wound around the outer circumferential shell above the fixed part.

Thus, bent pieces 9, 9' are provided on both sides of the intermediate portion of the yoke plate 5.
is bent, and the side surface of the tip of the magnetic piece 10 that is inserted between one end 8a of the coil 8 and the bent pieces 9 and 9' and protrudes from the lower surface of the intermediate part of the movable iron piece 6 is bent. piece 9.9
They are placed so that they face each other with a gap at the ends.

The present invention has the above-described configuration, and both ends of the coil 80 are inserted and connected in series to the distribution line, and when an overcurrent of a predetermined value or more flows through the distribution line, the magnetic flux created by the overcurrent flowing through the coil 8 causes the magnetic path 11 to The plunger 3 is attracted toward the lid 3 side by the magnetic flux, and the plunger is moved very slowly toward the lid 3 side against the spring force of the spring 4 and the viscous resistance of the oil.1. Finally, the upper end of the plunger 3 comes into contact with the lid 2 and the magnetic path 11
As the magnetic resistance decreases, the magnetic flux created by the overcurrent flowing through the coil 8 increases, and the lower surface of the free end of the movable iron piece 6 is attracted to the upper surface of the lid 2, and the movable iron piece 6
By the movement of , an overcurrent exceeding a predetermined value can be detected with time-limiting characteristics.

Next, when a short-circuit current flows through the distribution line, the magnetic flux generated by the short-circuit current flowing through the coil 8 flows through the magnetic path 11, and the magnetic flux generated due to the short-circuit current flowing through the one end 8a of the coil 8 flows through the magnetic path 12, and Since the short circuit current flowing through the coil 8 and its part 8a is extremely large, the magnetic flux flowing through the magnetic paths 11 and 12 is extremely large, and the free end of the movable iron piece 6 is The bottom surface is lid body 2
In this case, the magnetic flux flowing in the magnetic path 11 is delayed by the overcurrent flowing in the cylinder 1, or the magnetic flux flowing in the magnetic path 12 is hardly delayed with respect to the short circuit current, so the short circuit current is the raw stone.

Then, the lower surface of the free end of the movable iron piece 6 instantly comes into contact with the upper surface of the lid 2, which has the effect of quickly detecting short-circuit current.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional dashpot type overcurrent detection device, FIG. 2 is a sectional view of an embodiment of the present invention, and FIG. 3 is a sectional view taken along line X--X in FIG. 1 is a bottomed cylinder, 2 is a lid body, 3 is a plunger, 4 is a spring, 5 is a yoke plate, 6 is a movable iron piece, 7 is a return spring, 8
9 and 9' are bent pieces, and 10 is a magnetic piece.

Claims (1)

[Claims] 1 The plunger 3 is slidably housed in a bottomed cylinder 1 made of non-magnetic metal whose upper end opening is hermetically closed with a lid 2 made of a magnetic material to seal oil. A spring 4 is compressed between the plunger 3 and the plunger 3, and the lower surface of the free end of the movable iron piece 6, whose base end is pivoted to the tip of the yoke plate 5 whose base end is fixed to the outer peripheral body of the middle part of the cylinder 1, is attached to the lid. body 2
A return spring 7 is mounted so as to face the upper surface with a gap therebetween and act in a direction to separate the lower surface of the free end of the movable iron piece 6 from the upper surface of the lid body 2. In an oil dashpot type overcurrent detection device in which a coil 8 is wound around the outer circumferential body of the yoke plate 5, bent pieces 9, 9' are bent on both sides of the middle portion of the yoke plate 5 to form one end portion 8a of the coil 8. is inserted between the bent pieces 9, 9', and the side surface of the tip end of the magnetic piece 10, which is protruded from the lower surface of the base end of the movable iron piece 60, faces the tips of the bent pieces 9, 9' with a gap therebetween. Dashpot type overcurrent detection device.