HK1050431B - Multi-pole low voltage circuit breaker with one current measuring device per line - Google Patents

Description

Multipole low-voltage circuit breaker with a current measuring device for each pole

Technical Field

The invention relates to a multipole low-voltage circuit breaker having a housing and having a current measuring device for each pole, wherein each current measuring device has a conductor belonging to the switching contact arrangement of the pole and a secondary part through which the conductor passes.

Background

Circuit breakers of the above-mentioned type have been disclosed, for example, by US patent specification US 4,673,779 or US design patent US D347,623 in combination with US patent specification US 4,497,992. The object of the current measuring device is to generate a signal which is dependent on the current flowing in the poles and which is evaluated in an overcurrent tripping device in order to open the circuit for protecting the load from the electrical system. Since only one high current which is liable to cause a fault may flow in one pole of the circuit breaker, a current measuring device is assigned to each pole.

The secondary part of the current measuring device usually consists of a carrier and a winding which can be designed as a single layer or as multiple layers and is mounted thereon. In addition, these components are often provided with a housing or enclosure that protects them from injury and external influences. When manufacturing a low-voltage circuit breaker, the secondary parts of the current measuring device are selected according to the requirements of the user and are installed separately. For this purpose, suitable grooves or recesses are provided on the rear side of the housing of the circuit breaker, through which grooves the conductors leading to the switching contact arrangements project and at the same time form connection pieces for connection to a circuit to be protected. After the secondary part has been pushed onto the conductor, a suitable cover or lid is attached to the rear side of the housing in order to protect the secondary part of the current measuring device on the one hand and to support the conductor as close as possible to the connection on the housing of the circuit breaker on the other hand. These measures are due to the fact that the circuit breakers of the above-mentioned type are subjected to very high mechanical forces in the event of a short circuit, which can cause the circuit breaker and the projecting conductor to be damaged in the event of a failure of the busbar support.

Disclosure of Invention

The object of the invention is to improve the current measurement on a multipole low-voltage circuit breaker and to simplify the installation of these current measuring devices.

According to the invention, the above-mentioned object is achieved in that the secondary parts of the current measuring devices on all poles of the circuit breaker are arranged on the same support body, which has a through-opening for the conductor to pass through and a fastening element for detachably connecting the support body to the housing of the circuit breaker.

According to the invention, by combining the secondary parts of the current measuring devices on all poles into one unified assembly, it is possible to provide a plurality of matched and correlated detected units for current measurement in a multipole circuit breaker. This reduces the time it takes for mechanical installation and for calibration and commissioning of the finished circuit breaker. The multipolar support also improves mechanical strength by supporting the conductors in an assembled assembly.

The support body provided according to the invention can have receiving spaces for receiving the secondary parts, wherein the secondary parts are fixed in the receiving spaces by casting with a synthetic resin material. The same materials and processing methods can therefore be used for the production of the support body and for the fastening of the secondary part, as is known to date for the production of circuit breaker housings or housing parts and associated unipolar current measuring devices.

Within the scope of the invention, the support body with a substantially plate-like and rectangular basic shape can be designed as a part of a rear wall of the circuit breaker housing, wherein the receiving chamber is arranged on that side of the support body which faces the interior of the circuit breaker. By such an arrangement, the secondary part can be better protected from damage during operation of the circuit breaker and a favorable supporting effect is achieved for the conductor belonging to the current measuring device.

As already mentioned, the current measuring device can be of very different construction types on various low-voltage circuit breakers. One common type of construction is the Rogowski current transformer, which has a non-magnetic support surrounding a conductor and a single layer coil with a start and end of the single layer coil immediately adjacent. Unlike inductive current transformers, the output parameter of such a current sensor is not only related to the number of turns of the coil, but also to the geometric distribution and arrangement of the turns. According to a further development of the invention, the different transformation characteristics of the Rogowski current transformers due to machining tolerances are compensated for by providing each Rogowski current transformer with a resistive voltage divider and arranging these voltage dividers likewise on the support body. The Rogowski current transformer can thus be commissioned before it is installed in a circuit breaker, thereby facilitating this task with respect to the adaptations or calibrations that have hitherto been required on the finished circuit breaker.

The pressure dividers are designed to be adjustable by means of an adjusting mechanism, wherein all adjusting mechanisms are arranged on the rear side of the support body in an accessible manner. The current transformer or current sensor can be easily adjusted during the manufacturing process. In order to ensure that the adjustment that has already been carried out can be retained, however, it is proposed to prevent undesired operation of the adjustment mechanism by means of a contact-locking means that can be applied after the adjustment has been completed. As a touch-locking means, it is particularly suitable to use a spacer which covers an adjusting mechanism in each case.

As mentioned, the current measuring device of a low-voltage circuit breaker supplies an output parameter tripping device, which is processed in the tripping device, to the tripping device. The auxiliary power required for operating such a tripping mechanism is usually also taken from the conductors of the circuit breaker by means of a current transformer. In this case, it has often proven to be expedient to provide a separate current transformer for supplying auxiliary power, which is independent of the current measuring device. For this purpose, it has long been known to provide a current sensor for measurement purposes only and an inductor current transformer for supplying auxiliary power in the same housing. Within the scope of the invention, this embodiment can also be used on a multipole support body in that at least one current transformer for the power supply is arranged on the same support body.

Drawings

The invention is explained in detail below with the aid of embodiments shown in the drawings:

figure 1 is a schematic cross-section of a multipole low-voltage circuit breaker;

fig. 2 is a view showing a support body for a current measuring device provided in a three-pole circuit breaker, looking outward from an inner side facing the interior of the circuit breaker;

FIG. 3 is an outside elevational view of the support body illustrated in FIG. 2;

FIG. 4 is a side view of the support body shown in FIG. 2;

FIG. 5 is a view of an ironless sensor coil of a Rogowski current transformer as a single component of a current measuring device;

FIG. 6 shows the secondary components of an auxiliary current transformer;

fig. 7 is a perspective view of the three-pole support of fig. 2 to 4, in which it can be seen that the current sensor and the secondary part of the auxiliary current transformer are arranged in the housing cavity of the support;

fig. 8 and 9 are detail views of an embodiment of a current measuring device with an adjusting mechanism and a contact lock for the adjusting mechanism.

Detailed Description

The low-voltage circuit breaker 1, which is schematically shown in fig. 1, has a housing 2, on the rear wall 13 of which conductors 3 and 4 project for connection to an external circuit. The conductors 3 and 4 belong to a switching contact arrangement 5 having a stationary contact 6 and a movable contact 7. Above the switching contact arrangement 5, there is an arc chute 10 for extinguishing the arc generated when the switching contacts 6 and 7 open. The movable contact 7 is mounted on a movable contact support 11, and the movable contact support 11 is operated by a driving device 12 to realize the closing and the opening of the contact. The conductors 3 and 4 are connected directly to the switching contact device 5 and are supported on a rear wall 13 of the housing 2 against all forces occurring. The opening of the switching contact arrangement 5 in the event of a fault is controlled by a tripping mechanism 14, which is illustrated above the drive 12. For this purpose, the tripping device 14 receives a signal from a current measuring device 15, to which the lower conductor 4 belongs as a primary part and is surrounded by a secondary part 16 of a current sensor. The current sensor may be, in a known manner, an inductive current transformer, an ironless current transformer based on a Rogowski coil, and sensors operating according to other known principles. In this case, the components of a current measuring device are also understood to be auxiliary current transformers, which supply operating or auxiliary power to the electronic tripping device 14 in a known manner.

Fig. 2 to 4 show how the secondary part 16 is arranged and installed in the circuit breaker 1 of three-pole configuration. According to the invention, it is essential for the arrangement of the secondary part 16 that a common support body 20 for all poles of the circuit breaker 1 is provided, which support body 20 is made of a molding material, for example, for the production of the housing parts of the circuit breaker 1. The supporting body 20 has a corresponding rectangular through hole 21 for the upper conductor 3 of each pole of the circuit breaker 1. As can be seen in particular from fig. 3, the rectangular through-opening 21 is located on the rear wall 13 of the housing 2 of the circuit breaker 1, so that the conductor 3 is supported as far away as possible from the stationary contact 6, so that a good supporting action is achieved. The through-openings 21 are each surrounded by a receiving space 22 for receiving the secondary part 16 of the current measuring device 15. As already mentioned, a current transformer for supplying the tripping device 14 can also be provided in the receiving space 22.

The support body 20 has a flange 23 on its lower longitudinal side in order to be able to be fixed to the rear side of the circuit breaker 1. In order to receive the lug 23, a corresponding groove is provided in the rear wall 13 of the circuit breaker 1. The edge recesses 24 on the longitudinal sides of the support body 20 opposite the overlap 23 and the through-holes 25 provided between the poles are provided for fixing elements, in particular bolts, which are inserted into the housing 2. The support body 20 is securely fixed to the rear wall 13 of the housing 2 (fig. 1) by the attachment flange 23.

As an example of a current sensor, a Rogowski coil 26 with a connecting lead 27 corresponding to the secondary part 16 shown in fig. 1 is shown in fig. 5. Such a coil provides a signal that can be analyzed electronically for controlling the trip mechanism 14. The tripping device 14 requires an auxiliary electrical energy in order to be able to carry out the necessary evaluation and calculation and, if necessary, to actuate a release electromagnet. As shown in fig. 6, a separate auxiliary current transformer with a secondary part 31 is provided for supplying this auxiliary power, the primary winding of which (as in the case of the Rogowski coil 26) can be formed by the corresponding conductor 4 of the circuit breaker 1 (see fig. 1). The secondary part 31 shown in fig. 6 comprises a core 32 and a secondary coil 33 fitted thereon. For the sake of simplicity of illustration, a conductor as a primary coil is shown only in dashed lines in fig. 5 and 6.

In fig. 7 it can be seen that the secondary part shown in fig. 5 and 6 is arranged in the receiving chamber 22 of the support body 20. Looking first at the right receiving chamber 22, the outer side of the receiving chamber 22 is hollow-cylindrical and matches the diameter of the Rogowski coil 26. The inner boundary of the receiving chamber is formed by a flange 34 surrounding the through hole 21.

Fig. 7 shows a left-hand half of a state that is formed during the production of a current measuring device 15, in which a Rogowski coil 26 and a secondary part 31 of an auxiliary current transformer are accommodated in a receiving space 22. The Rogowski coil 26 is located on the floor of the receiving chamber 22 and is aligned with its hollow cylindrical periphery. The secondary part 31 of the auxiliary current transformer is positioned thereon and is fitted over the flange 34.

Although it is possible to fix the coil arrangement in the receiving chamber 22 by means of a cover which can be connected to the support body 20, it is more preferred to cast synthetic resin. The synthetic resin encloses the connecting leads of the coil and the secondary part and thus protects them more reliably against all external influences. Such a synthetic resin casting 35 is shown in the middle of fig. 7.

Fig. 7 additionally shows that the lower region 36 of the support body 20 between the central receiving space 22 and the right-hand receiving space 22 is closed. In this region, an actuating element 30 of the voltage divider is provided, which is assigned to the current sensor or the Rogowski coil 26 (see fig. 3). They only need to be adjusted once after the current measuring device 15 has been installed. To prevent their subsequent accidental operation, a contact lock 37 shown in fig. 8 and 9 can be provided. The contact-locking element is shown as a flap which can be fixed by means of a screw and can be prevented from rotating by a hook head 38.

By assembling the current sensors of all poles of the circuit breaker with the secondary parts of the auxiliary current transformer, an assembled and electrically debugged assembly is obtained. The calibration of the secondary parts and the overall detection of a multipole current measuring device can be carried out before they are installed in the circuit breaker, which greatly simplifies the work. This reliably prevents errors, for example, due to the mixing of previously sorted and prepared secondary parts. And also ensures that all secondary parts are spaced at a fixed and constant spacing and thus eliminates the problem of subsequent failure and tolerances.

Claims (8)

1. A multipole low-voltage circuit breaker (1) with a housing and with a current measuring device (15) for each pole, wherein each current measuring device has a conductor (4) of a switching contact device (5) belonging to the pole as a primary part and a secondary part (26, 31) through which the conductor (4) passes, characterized in that: the secondary parts (26, 31) of the current measuring devices (15) on all poles of the circuit breaker (1) are arranged on the same support body (20), and the support body (20) is provided with a through hole (21) for the conductor (4) to pass through and a fixing mechanism for connecting the support body (20) and the shell (2) of the circuit breaker (1).

2. Low voltage circuit breaker as claimed in claim 1, characterized in that: the support body (20) has a receiving space (22) for receiving the secondary parts (26, 31), and the secondary parts (26, 31) are fixed in the receiving space (22) by casting with a synthetic resin (35).

3. Low voltage circuit breaker as claimed in claim 2, characterized in that: the support body (20) having a substantially plate-like and rectangular basic shape is configured as part of a rear wall (13) of the housing (2) of the circuit breaker (1), and the receiving chamber (22) is arranged on that side of the support body (20) which faces the interior of the circuit breaker (1).

4. Low voltage circuit breaker as claimed in claim 1, characterized in that: when Rogowski coils (26) are used as the secondary part (26), a resistive voltage divider is associated with each Rogowski coil (26) and is likewise attached to the support body (20).

5. Low voltage circuit breaker as claimed in claim 4, characterized in that: each potentiometer is designed to be adjustable by means of an adjusting mechanism (30), and all adjusting mechanisms (30) are arranged in a contact-capable manner on the side of the support body (20) that is accessible from the outside.

6. Low voltage circuit breaker as claimed in claim 5, characterized in that: undesired operation of the adjusting mechanism (30) is prevented by a contact closure (37) which can be applied after the adjustment is completed.

7. Low voltage circuit breaker as claimed in claim 6, characterized in that: the contact-locking element (37) is formed by a spacer which covers an adjusting mechanism (30).

8. Low voltage circuit breaker as claimed in any one of the preceding claims, characterized in that: a current transformer is arranged on the shared support body (20) and is used for supplying power to a tripping mechanism (14) of the circuit breaker (1).