WO2001082440A1

WO2001082440A1 - Undervoltage release

Info

Publication number: WO2001082440A1
Application number: PCT/EP2000/010434
Authority: WO
Inventors: Johann Wolf
Original assignee: Siemens Aktiengesellschaft
Priority date: 2000-04-25
Filing date: 2000-10-23
Publication date: 2001-11-01
Also published as: EP1150411A1

Abstract

In an undervoltage (1) release having a release device (4), which outputs a release pulse (PA) for actuating a switching contact (7) in the event of a predeterminable voltage limit value (U2) being undershot, means for setting the voltage or release limit value (U2) are provided.

Description

Undervoltage release

The invention relates to an undervoltage release having a release device, which outputs a release pulse for actuating a switching contact in the event of a predeterminable voltage limit value being undershot.

An undervoltage release causes an electrical switch, for example a power circuit-breaker, to open or close, with or without delay, if the voltage at the terminals thereof falls below a given value. In this case, the voltage limit value which, when undershot, causes the release relay to output a release pulse for actuating the electrical switch or generally a switching contact is usually set in a fixed manner. An undervoltage release of this type in which the voltage limit value is set in a fixed manner by means of a zener diode connected downstream of a rectifier is disclosed e.g. in DE 2 239 654 Al and in DE 39 12 601 Al . Since an undervoltage release is generally designed as an attachment^' device or attachment module for an electrical protective circuit-breaker, in particular for a line protective circuit-breaker, different release types with differing voltage limit values, the undershooting of which is intended to give rise to a release operation, have to be provided in practice for different applications and, furthermore, on account of permissible voltage ranges prescribed by regulations. In addition to the associated disadvantage of stock keeping on account of the required diversity of types, extremely undesirable problems often arise in particular in the course of the interaction of a plurality of undervoltage releases in an installation.

The invention is based on the object, therefore, of specifying an undervoltage release, which, whilst avoiding theabove entioned disadvantages, can be used for different applications, in particular for different^' rated values or rated voltages of an electricity supply system to be switched.

This object is achieved according to the invention by means of the features of claim 1. To that end, the undervoltage release is designed to be adjustable, i.e. the undervoltage release has means for setting the voltage limit value or the release threshold. The setting is expediently effected by altering a reference value in the form of an adjustable comparison voltage, which is compared with the voltage to be monitored. In this case, a release operation takes place if the voltage to be monitored falls below the respective comparison voltage that has been set, and hence the reference or release value.

To that end, in an advantageous refinement, a comparator circuit is provided, to whose inputs are fed the voltage to be monitored, on the one hand, and the respective variable comparison voltage that has been set, and whose output is connected to an input of a' bistable multivibrator, for example of a flip-flop or of a multivibrator. On account of the output state of the comparator circuit which changes in the event of the set release or voltage limit value being undershot, the multivibrator connected on the output side to the release device in the form, for example, of a release relay likewise changes over the output state thereof, with the result that the release device outputs a release pulse for actuating a protective circuit-breaker connected to the undervoltage release. In this case, the voltage to be monitored is fed to a first input of the comparator circuit expediently via a rectifier circuit. A voltage divider can be connected downstream of the latter in order to reduce the voltage which is passed to the first input of the comparator circuit.

The comparison or reference voltage may be set by means of an operating element provided on the housing side, via a voltage divider coupled to said operating element within the housing. In this case, the setting may be effected in an analog manner, e.g. by means of a potentiometer with or without latching positions, or else in steps by means of an appropriately configured switch, e.g. a so-called dip switch. Digital setting, e.g. by means of a coding switch, may also be provided. A combination of these setting variants is also expedient, e.g. in the form of a stepwise range preselection and analog setting of intermediate values .

In accordance with a preferred embodiment, the comparison or reference voltage is fed to the second input of the comparator circuit via a bus coupler. This enables, in a particularly advantageous manner, remote setting of the release or voltage limit value. In this case, the bus coupling to the comparator is expediently effected via an analog-to-digital converter. Such a bus connection may be realized either via an external or via an internal bus coupling. What is particularly advantageous in this case is the use of a pressure contact system - interacting with a bus coupler within the housing - for contact connection on a top-hat or data rail, as is' used in bus-coupled ancillary components for low-voltage switching devices. An example of a bus-coupled system of this type is the standardized European Installation Bus (EIB) .

The particular advantages obtained with the invention are that with an undervoltage release whose release or voltage limit value is variable and can thus be set as required, the diversity of types and, consequently, the stock-keeping can be reduced to a minimum. Furthermore, the desired release value can be adjusted to the intended release value even during the operation of the undervoltage release and, in particular, of the low-voltage switching device connected thereto. Furthermore, adjustment with other undervoltage releases is possible at any time in a simple manner.

Furthermore, remote setting via a bus coupling enables superordinate control and readjustment of the release or voltage limit value set at the respective undervoltage release, independently of the respective installation location of the corresponding undervoltage release within a complex system.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing, in which: FIG. 1 schematically shows an undervoltage release interacting with a protective circuit-breaker, with a circuit for setting a release limit value,

FIG. 2 shows an adjustable undervoltage release in accordance with FIG. 1 with a bus coupling and a release relay interacting with an individual switching contact, FIG. 3 shows a housing of an undervoltage release in accordance with FIG. 1 with an actuating element accessible at the front and having a hinged cover, FIG. 4 shows a housing in accordance with FIG. 3 with a slidable cover, FIG. 5 shows a housing of an undervoltage release in accordance with FIG. 1 with an actuating element which is inaccessible in the built-in state, and FIG. 6 shows a housing for an undervoltage release in accordance with FIG. 2 with a contact system for bus coupling. Mutually corresponding parts are provided with the same reference symbols in all the figures. The undervoltage release 1 illustrated in FIG. 1 comprises an operational amplifier in comparator circuit 2 and a multivibrator 3, which is connected downstream of the latter and, on the output side, is connected to a release device in the form of a release relay 4. The release relay 4 is mechanically coupled to a latch 5 of an electrical protective circuit-breaker 6, e.g. line protective circuit- breaker, whose switching contacts 7 are connected into the phase lines LI, L2, L3 of an electricity supply system or supply network. A first input E_ki of the comparator circuit 2 is connected to an input stage 8, to which the voltage ϋ_ιn to be monitored is fed on the input side. The input stage 8 comprises a rectifier circuit 8a, symbolized by a diode, and a voltage divider circuit 8b, symbolized by non-reactive resistors. The second input E_k2 of the comparator circuit 2 is connected to a further input stage 9 having a manually variable voltage divider in the form, for example, of a potentiometer, which can be actuated by means of an operating element 10, a coding switch or a dip switch.

In the input stage 8, the voltage U_in to be monitored is rectified by means of the rectifier circuit 8a. The rectified voltage U_in, which may have been reduced by means of the voltage divider circuit 8b, is fed as input voltage Ul to the first input E_kι of the comparator circuit 2. A reference or comparison voltage U2, which is set as required by means of the voltage divider of the second input stage 9 by manual actuation of the operating element 10, is fed to the second input E_k2 of the comparator circuit 2.

In this case, the setting range for the comparison voltage U2 expediently covers all or- at least a multiplicity of release or undervoltage limit values that are to be represented by such an undervoltage release 1. The voltage supply - provided for generating the reference or comparison voltage U2 - to the second input stage 9 is in this case effected, in a manner not specifically illustrated, preferably from the supply voltage of an electronic unit that is usually provided in such an undervoltage release 1.

Via its output A_k, the comparator circuit 2 supplies a release or state signal S_A^ which is fed to the multivibrator 3 - designed e.g. as a bistable multivibrator or as a flip-flop - via the input El thereof as input signal.

During normal operation without an undervoltage, the multivibrator 3 has a first signal state at its output Al . With this signal state of the multivibrator 3, a voltage U3 is present at the release relay 4, i.e. across the release coil thereof. If, in the event of an undervoltage, the voltage U_in to be monitored and, accordingly, the voltage Ul at the first input E_ki of the comparator circuit 2 falls below the reference value set in the second input stage 9, and hence below the comparison voltage U2 at the second input E_k2 of the comparator circuit 2, then the multivibrator

3 changes over its signal state at the output Al on account of a corresponding change in the state signal S_A of the comparator circuit 2.

If the signal state of the multivibrator 3 is in this case e.g. high during normal operation, then this signal state changes over to low in the event of the input voltage Ul at the comparison circuit 2 falling below the comparison voltage U2, with the result that the release relay 4 outputs a release pulse P_A on account of the absent voltage U3. The release pulse P_A actuates the latch 5 of the protective circuit-breaker 6, with the result that the switching contacts thereof are actuated. Instead of the actuation of the protective circuit-breaker or power circuit-breaker 6, --.the release pulse P_A of the release relay

4 may also be passed on for a different purpose, for example via an operating current release to an individual switching contact. This is indicated in FIG. 2.

Since the multivibrator 3 is expediently of bistable design, the signal state - set on account of the comparison voltage U2 being undershot - at the output Al of the multivibrator 3 is preserved even after a renewed rise in the voltage U_in to be monitored and hence in the input voltage Ul to its voltage value corresponding to normal operation without an undervoltage, until a corresponding acknowledgement signal S_Q is passed to a second input E2 of the multivibrator 3 by means of an acknowledgement switch 11. On account of the acknowledgement signal S_Q, the multivibrator 3 changes over to its previous stable signal state, with the result that the high level is again present at the output Al and the voltage U3 is present at the release relay 4. Accordingly, the electromagnetic release relay 4 pulls its armature back into the starting position, with the result that the release pulse P_A is cancelled. In the case of the adjustable undervoltage release 1 illustrated in FIG. 2, the second input E_k2 of the comparator circuit 2 is connected via an analog-to-digital converter 12 to a bus coupler 13, which is contact connected to an installation bus 14 on the input side. In this case, the comparison voltage U2 is advantageously set or altered by remote setting via the installation bus 14 and the bus coupler 13. To that end, a corresponding digital control signal S_D, supplied by the bus coupler 13, is converted into the analog comparison voltage U2 by means of the digital-to- analog converter 12. When a corresponding processor is integrated in the bus coupler 13, the latter can also output the analog comparison voltage U2 directly. Moreover, both the input voltage Ul derived from the voltage _, U_in to be monitored and the comparison voltage U2 can be fed as digital values to the inputs E_ki and E_k2, respectively, of the comparator circuit 2.

The manual setting of the comparison or reference voltage U2 and hence of the voltage limit value of the adjustable undervoltage release 1 in accordance with FIG. 1 is effected by means of the operating element 10, which, in the case of a housing 15 of such an undervoltage release 1 as illustrated in Figures 3 and 4, is arranged on a housing front side 16, which is accessible even in the assembled state. The operating element 10 may be designed in the form of a rotary switch, dip switch, coding switch or the like. By means of the operating element 10, which is coupled or connected to the voltage divider of the second setting stage 9 within the housing in a manner not specifically illustrated, the comparison voltage U2 and hence the level of the response threshold of the undervoltage release 1 is set or altered. In order to prevent an undesirable change in the setting of the comparison voltage U2 and hence the release or voltage limit value, the operating element 10 can expediently be closed off by means of a transparent covering flap 17 (FIG. 3) or a likewise transparent covering slide 18 (FIG. 4) . Just like the housing 15 in accordance with Figures 3 and 4, the housing illustrated in FIG. 5, for a manually adjustable undervoltage release 1, is also provided with a dovetail-like cutout 20 on the housing underside 19, so that the housing 15 can be placed onto a standardized top-hat rail after the manner of a series installation device.

In the embodiment according to FIG. 5, the operating element 10 is arranged on a housing long side 21 or on a housing end 22. Consequently, in the case of a distribution installation of the undervoltage release 1 in an equipment interconnection with a plurality of low-voltage switching devices strung together, the operating element 10 is no longer externally accessible. The manual setting of the comparison voltage U2 and hence of the release or voltage limit value of the adjustable undervoltage release 1 is then effected before the housing 15 thereof is inserted into the equipment interconnection or before a series installation device adjacent to said undervoltage release 1 is placed onto such a top-hat rail and the housing side 21 having the operating element 10 is covered.

FIG. 6 shows a preferred embodiment of the housing 15 of an undervoltage release 1 in accordance with FIG. 2, which release can be set under remote control via the bus coupler 13. In this variant, no external setting means in the form of manually actuable operating elements are provided. The comparison voltage U2 and hence the response threshold of the adjustable undervoltage release 1 is implemented via the installation bus 14, to which the bus coupler 13 of the undervoltage release 1 is connected within the housing via a pressure contact system 23 provided in the region of the cutout 20 of the housing 15. Therefore, this embodiment is particularly suitable for linking the adjustable undervoltage release 1 into the EIB system.

Claims

Patent claims

1. An undervoltage release having a release device (4), which outputs a release pulse (P_A) for actuating a switching contact (7) in the event of a predeterminable voltage limit value (U2) being undershot, characterized in that means for setting the voltage limit value (U2) are provided.

2. The undervoltage release as claimed in claim 1, characterized in that the voltage limit value is a variable comparison voltage (U2) fed to a comparator circuit (2), the comparator circuit (2) outputting a state signal (S_A) for generating the release pulse (P_A) in the event of a voltage

(U_in) to be monitored deviating from the comparison voltage (U2) .

3. The undervoltage release as claimed in claim 2, characterized in that a bistable multivibrator (3), which, on the output side, is connected to ^• the release device (4), is connected downstream of the comparator circuit (2) .

4. The undervoltage release as claimed in claim 2 or 3, characterized in that the voltage (U_in) to be monitored is fed to a first input (E_ki) of the comparator circuit (2) via a rectifier circuit (8a) .

5. The undervoltage release as claimed in claim 4, characterized in that the rectified voltage (Ul) to be monitored is fed to the first input (E_ki) of the comparator circuit (2) via a voltage divider circuit (8b) .

6. The undervoltage release as claimed in one of claims 2 to 5, characterized in that the comparison voltage (U2) is fed to a second input (E_k2) of the comparator circuit (2) via a bus coupler (13) .

7. The undervoltage release as claimed in claim 6, characterized in that an analog-to-digital converter (12) is connected downstream of the bus coupler (13) .

8. The undervoltage release as claimed in one of claims 1 to 7, characterized by a housing (15) with an actuating element (10) for manual setting of the comparison voltage (U2) .

9. The undervoltage release as claimed in claim 6 or 7, characterized by a housing (15) with a contact system (23) connected to the bus coupler (13) for coupling to an installation bus (14) .

10. The undervoltage release as claimed in one of claims 1 to 9 as an attachment module for a low-voltage switching device, in particular for a line protective circuit-breaker (6).