DE1014636B - Arrangement for switches and relays in multi-phase alternating current circuits to actuate a trip device - Google Patents

Description

The invention relates to an arrangement for switches and relays in multi-phase alternating current circuits with bimetal strips working in the same direction for actuating a release device symmetrical overload and for earlier actuation in the event of asymmetrical loading. at asymmetrical load, d. H. with single-phase operation, three-phase motors are also thermally endangered if the current consumption of the windings still powered is due to a lower external load does not exceed the rated current. So there is the task of a safe shutdown in this case too of the motor to ensure that it does not heat up during single-phase operation avoid. Purely overcurrent-dependent releases cannot guarantee protection, as they only switch off when if the nominal current is exceeded by a certain amount. Unbalanced load thus requires earlier tripping than symmetrical overload.

Trip devices are already known which perform the task described above, including those in which the bimetal strips are connected to one another via two-armed levers. However, are the known arrangements are not suitable for all types of devices and are also structurally quite complicated built up. The invention now shows one. Way how with the help of simple means a solution to this Task can be achieved, and is seen in the fact that the lever is cushioned or resilient are designed so that with less deflection of a strip compared to another of the release path or the release force of at least one other strip to achieve an earlier release enlarged. The lever can be on a compression spring, which the lever in the working direction against the Bimetal strip presses, be rotatably mounted.

The drawing shows exemplary embodiments with the essential features in a simplified form the invention shown in front view. Only the rectangular end faces are of the bimetal strips drawn. It shows

Fig. 1 bimetal strips lying in one plane with two-armed levers that are mounted on springs,

Fig. 2 bimetal strips lying in one plane with two-armed, rotatably mounted, elastic levers and

Fig. 3 bimetallic strips arranged one behind the other, which are connected to one another via springs and rotatably mounted levers are connected.

In Figure 1, a, the bimetallic strips are denoted by 1, 2, 3, the two-armed levers 4, 5, 6 and the springs that carry them and are attached to the stationary surface 10 are denoted by 7, 8 and 9. The dashed line A gives the arrangement for switches and relays

in multi-phase AC circuits

for actuating a release device

Applicant:

Voigt & Haeffner Aktiengesellschaft,
Frankfurt / M., Hanauer Lands tr. 142-172

Dr. phil. Hans Johann Hochstadt (district of Hanau),
has been named as the inventor

The release position for all images, that is , if a bimetal strip bends through to line A , then release should take place. Instead of three levers 4, 5, 6, only two levers 4, 5 can be used, as shown in Figure 1, b and 1, c. Since two levers act on the middle bimetal strip in this case, it is pushed a little further upwards than the others, but this can be compensated for by an appropriate adjustment. The initial position of the bimetal strips in the cold state, when no current flows, is shown in Figure 1, a, the position in the operating state in Figure 1, b and a possible position in the case of asymmetrical load in Figure 1, c. The middle bimetal strip 2 has remained in its initial position or has returned to it due to the failure of the associated phase. As a result, the levers 4, 5 are inclined, and the springs located under the levers are compressed more than in the operating state according to Figure 1, b, so that an additional force is exerted on the two outer bimetal strips 1 and 3 and so compared to the symmetrical Overload with the asymmetrical load an earlier trip takes place. Instead of the spring-mounted levers 4, 5, elastic levers 11, 12, as shown in Figure 2, can also be used. The levers 11 and 12 are rotatably mounted on stationary stands 13 and 14. The positions of the bimetal strips in Figure 1, a, 1, b correspond to the positions in Figure 2, a and 2, b. If the outer bimetallic strip 3 remains, the position illustrated in Figure 2, c results. Because the outer strip is left behind, the middle strip is supported in its upward movement by the lever 12 and can therefore trigger an earlier release.

709 65935

i 014636

If the three bimetallic strips are not arranged in one plane, but one behind the other, this results in the embodiment shown in Figure 3. Here, the bimetal strips 1, 2 and 3 are connected to one another by springs 16, 17, 18 and 19 which are attached to levers 20 and 21 and to the bimetal strip itself. The levers 20 and 21 are rotatably mounted on stationary stands 22 and 23.

Claims (2)

PATENT CLAIMS: 10 1. Arrangement for switches and relays in multiphase AC circuits with bimetal strips working in the same direction to actuate a release device in the event of symmetrical overload and for earlier actuation in the event of asymmetrical loading, whereby the bimetallic ■■ iff strip about two-armed lever with one another Ia _1: standing connection, characterized in that the lever daij such cushioned or resilient off ^'1; are formed so that with less deflection of a strip compared to another de? AtIs- ¹ " ¹ " ¹¹¹ release path or the release force at least one: ;; the other strip is enlarged to achieve an earlier release. A, 2. Arrangement according to claim 1, dad / Etrch characterized in that the levers on a compression spring,
which presses the levers in the working ^{direction against the bi-1} : metal strips, are rotatably mounted. Considered publications:
Austrian Patent No. 164 343;
U.S. Patent No. 2,713,623. 1 sheet of drawings © 7 (© 659/335 8.57