DE408439C - Protection device for electrical circuits consisting of a maximum current and heat release - Google Patents

Description

The invention relates to such protective devices for electrical circuits, in which a tripping armature surrounded by a magnet and heating coil both when a maximum current is exceeded and even after the object to be protected has exceeded a certain temperature A movement is experienced even at a low current intensity, causing the to-be-protected

ίο circuit directly or indirectly to Shutdown is brought.

Attempts have already been made to train such facilities so that they are after Responding to both excessive amperage and excessive heating return automatically to their rest position each time and thus become usable do. However, the previous facilities of this type are proportionate in their design intricate and sensitive and consequently not very reliable.

The purpose of the invention is to design the release device so that it is at the simplest and compact design guarantees absolute reliability. This purpose is achieved according to the invention essentially in that the of the magnetic and Heating coil influenced trip armature has a non-magnetic weight core, with to which it is connected by an easily fusible solder joint, if the permissible maximum current limit, the armature with the weight core attached to it is drawn into the solenoid coil, while rend softens the solder joint when the maximum permissible temperature is exceeded and the an anchor freed from the weight core by a relatively small one Current is drawn into the coil and thereby the shutdown of the endangered Circuit caused.

The anchor and weight core are expediently designed to be telescopically telescopic, the tubular armature loosely enclosing the weight core at its upper end on a central rod is attached, which is guided displaceably in a bore of the weight core, which is closed at the bottom and is soldered to easily fusible metal.

The subject of the invention is shown in one embodiment in the drawing : shown, namely show:

Fig. Ι a longitudinal section through the ' protective device in the rest position,

Fig. 2 shows the raised anchor with the weight core still lowered, d. H. when responding the solder joint,

Fig. 3 and 4 the special design of the anchor.

Inside the insulating body 1, which at the same time forms a thermal protection, loading . is found as the pulling and heating element; Nende coil 2, which from the current of the ^{apparatus to be:} protected, z. B. a crane motor is traversed. The coil 2 is wound on a thin-walled metal cylinder 3 and acts on the trigger element located therein. This consists essentially of a tubular armature 4 made of magnetic material and a weight core arranged therein, which should have a high specific weight, but the lowest possible specific heat and z. B. can consist of lead, which is clad on the outside with a thin brass jacket. The armature 4 is also provided in the upper part with a thin brass jacket 7, the cover 8 of which is fastened to a metal rod 9 which is guided in a central bore 10 of the weight core 5, which is closed at the bottom. The bore of the weight core 5 is lined with a brass sleeve 11, which is narrowed at the top by an insert 12, and to which the rod 9 is soldered with its lower thickened end 14 and possibly also above the insert 12 by easily fusible metal. The release armature 4 with the weight core 5 is supported in the rest position shown in Fig. 1 on a cross piece 15, which is arranged adjustable in height by means of the nut 16 on the laterally slotted sleeve 17 of the housing base in order to thereby reduce the magnetic effect of the To be able to regulate the coil on the armature.

The tripping anchor 4 is, as can be seen from Fig. 3 and 4, widening towards the top side cutouts and thus at this point in the shape

4084B9

brought by two tips 20. The setting of the armature takes place in such a way that the largest part of the iron body, namely the lower annular part 4, in the rest position is completely outside the coil 2 and only the tips 20 in the cavity of the coil protrude. On the one hand, this training enables the armature to be set very precisely on a certain amperage enabled, on the other hand it is achieved that the trigger element can be used for both direct current and alternating current without using a laminated iron body.

Above the release, a metal web 21 is arranged opposite on the housing cover, which is lifted by the armature when it is triggered, creating a conductive connection between the Contacts 22 of an auxiliary circuit produces, whereby the disconnection in a known manner of the endangered circuit can be initiated.

The device works as follows:

In the position of the release shown in Fig. 1, as long as the dangerous state in the heating of the windings of the power consumer to be protected and thus the soldering of the soldering point has not occurred, the release is to be regarded as an anchor weighted down by the lead weight, which only occurs when a; certain adjustable amperage (the '. multiple of the normal operating amperage) is pulled into the interior of the coil 2 and the j

Circuit 21, 22 actuated so that the endangered power consumer is switched off. j If a dangerous temperature occurs for!

the motor to be protected, since the coil of the release can have approximately the same time constant as the motor to be protected, such a heating within the coil 2 will have occurred that the easily fusible solder softens. Now, a \ much less force is required to 'the iron armature 4 with the metal cylinder 7; and to lift the pin 9 connected to it via the cover 8, the lead core 5 remaining on the lower support 15.

g ₀ After responding, the armature falls back into its rest position due to gravity. ': The conditions can now be chosen so that when the dangerous state occurs, the armature working without the lead weight responds below the normal operating current every time, whereas in the case of heavy! tem anchor the response at higher values, ζ. B. at two to three times the operating current. The sensitivity of the release after the dangerous temperature has occurred remains until the temperature of the motor at risk and thus also the heat emanating from the coil have decreased to such an extent that the soldering point has been soldered again. After this condition occurs, the release is again insensitive to the operationally permissible excess current. ♦

The advantage of the trigger over the previous versions is how easy visible, mainly in the extremely simple, compact design with no joints, Springs etc. are used and guarantee absolute reliability is performing. The use of an additional weight with a high specific weight and at the same time lower specific heat such. B. lead, is particularly beneficial for the response of the release in the event of brief, high overloads that are just below the current strength at which the trigger element comes into effect electromagnetically.

Claims (4)

Patent claims: r. Protection device consisting of a high current and thermal release for electrical circuits, characterized in that the under effect A release armature (4) standing next to a heating and magnetic coil, loosely encloses a non-magnetic weight core (5) and is connected to it by an easily fusible solder joint. 2. Protection device according to claim r, characterized in that the tubular Trip anchor (4) is attached with its upper end to a central rod (9), which is closed at the bottom Bore (10) of the weight core (5) out and through easily meltable Metal is soldered in place. 3. Protection device according to claim 1, characterized in that the tubular Release anchor (4) through cutouts widening upwards into the Cavity of the coil protruding tips (20) is provided. no 4. Protection device according to claim 1, characterized in that the anchor (4) and the weight core (5% in the rest position on a thread in the Support the height-adjustable support (15). 1 sheet of drawings.