POWER DISTRIBUTION SYSTEM FOR CONNECTION TO AN AC VOLTAGE NETWORK

Abstract

A power distribution system for connection to an AC voltage network, having a UPS power supply unit for uninterruptible power supply with a network-side input and with at least one output to which a number of loads are connected or can be connected in parallel load circuits, wherein a protective device having an electromechanical tripping device, in particular a thermal/magnetic tripping device, and having an evaluation and tripping unit is connected in the or each load circuit, which tripping unit trips the tripping device on the basis of an electronic overload and/or short-circuit characteristic curve and on the basis of the output voltage from the UPS power supply unit.

Claims

1. A power distribution system for connection to an AC voltage network, the system comprising: a UPS power supply unit for uninterruptible power supply with a network-side input; at least one output to which a number of loads are connectable in parallel load circuits; a protective device having an electromechanical tripping device or a thermal/magnetic tripping device and having an evaluation and tripping unit is connected in at least one of the load circuits, the tripping unit actuating the tripping device and trips the protective device based on an electronic overload and/or short-circuit characteristic curve and based on an output voltage from the UPS power supply unit.

2. The power distribution system according to claim 1, wherein the evaluation and tripping unit is supplied with the output voltage of the UPS power supply unit, the voltage being detected on the power supply side or in the protective device, and wherein a current is detected in a tripping path between a power supply-side output and a load output of the protective device.

3. The power distribution system according to claim 2, wherein the evaluation and tripping unit trips the protective device when the detected current exceeds a predetermined current value and the detected output voltage of the UPS power supply unit falls below a predetermined voltage value.

4. The power distribution system according to claim 1, wherein the protective device has an input for inputting a parameter representing a maximum load of the UPS power supply unit into the evaluation and tripping unit, wherein the parameter is used for matching the detected actual current with an overload characteristic curve of the UPS power supply unit, the overload characteristic curve being dependent on the parameter.

5. The power distribution system according to claim 1, wherein the protective device has an input for inputting a parameter representing the rated load of the connected load into the evaluation and tripping unit.

6. The power distribution system according to claim 4, wherein the evaluation and tripping unit based on the entered parameter and/or the entered parameter forms the electronic characteristic curve of an overload region or a short-circuit region, wherein the time-current value pairs of which are smaller than those of the overload characteristic curve of the UPS power supply unit but larger than those of the connected load or of the connected device in normal or rated load operation.

7. The power distribution system according to claim 1, wherein tripping of the protective device in an affected load circuit only occurs when, in a case when the overload characteristic curve of the UPS power supply unit is exceeded by the detected actual current, the detected output voltage of the power supply unit falls below a voltage limiting value.

8. The power distribution system according to claim 1, wherein the electronic characteristic curve for an overload and the electronic characteristic curve of the evaluation and tripping unit of the protective device, wherein the electronic characteristic curve representing a maximum load of the UPS power supply unit, in an event a short circuit, meet in a characteristic curve region.

9. The power distribution system according to claim 8, wherein, if the electronic characteristic curve for the overload and/or the electronic characteristic curve in the event of a short circuit are exceeded, the protective device is tripped by the evaluation and tripping unit.

10. The power distribution system according to claim 1, wherein the electronic characteristic curves of the evaluation and tripping unit represent a maximum possible load current during a converter operation of the UPS power supply unit, at which the output voltage thereof does not fall below a defined limit value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0026] FIG. 1 schematically shows a power distribution system connected to an AC voltage network with a number of load circuits, supplied without interruption by a UPS power supply unit, in each case with an electromechanical circuit breaker for protection against overload and short circuit;

[0027] FIG. 2 schematically shows the circuit breaker with a thermal-magnetic tripping device as well as with an evaluation and tripping unit (electronics) and with current and voltage measurement;

[0028] FIG. 3 schematically shows an algorithm for determining a tripping event as implemented in the evaluation and tripping unit; and

[0029] FIG. 4 shows the electronic and B-characteristic curve profile of the circuit breaker during battery operation of the UPS power supply unit.

DETAILED DESCRIPTION

[0030] FIG. 1 schematically shows a power distribution system 1 with an uninterruptible power supply, which is referred to hereinafter as UPS power supply unit 2 and which is connected to an AC voltage network (L, N, PE) 4 via AC voltage inputs E.sub.AC and fuses 3 arranged upstream in the exemplary embodiment. UPS power supply unit 2 has a converter path 2a and a bypass path 2b. A switching device 5, for example, in the form of a contactor or switching electronics, enables switching between converter path 2a and bypass path 2b as well as its connection to a load-side AC voltage output A.sub.AC of UPS power supply unit 2.

[0031] Converter path 2a of UPS power supply unit 2 is substantially formed by a network-side AC-DC converter (rectifier) 6 and a DC intermediate circuit 7 downstream thereof, as well as a DC-AC inverter 8. A battery or accumulator 9 is connected to DC intermediate circuit 7. The converter operation of UPS power supply unit 2 is symbolized by the arrow marked SB, whereas the battery operation of UPS power supply unit 2, which is also referred to as autonomous operation, is symbolized by the arrow marked AB.

[0032] A number of load circuits L.sub.m with m=1, 2, . . . , n, parallel to one another, are connected to the AC output A.sub.AC of UPS power supply unit 2. In the exemplary embodiment, an electromechanical protective device GS.sub.m with m=1, 2, . . . , n, in particular a thermomagnetic line circuit breaker with B characteristics, is connected in each load circuit L.sub.m. In the or each load circuit L.sub.m, there is a load 10, which is connected to the respective protective device GS.sub.m via a corresponding output A.sub.m of power distribution system 1. Load 10 represents, for example, a device supplied by power distribution system 1.

[0033] FIG. 2 shows the structure or functional components of the respective electromechanical protective device GS.sub.m. A thermal-magnetic tripping device 12 and switch contacts 14, 15 actuated by the device via a switch latch 13 are connected in a tripping path 11 between the LINE input E.sub.L, connected to the AC voltage output A.sub.AC, and an output A.sub.L of protective device GS.sub.m, output A.sub.L being connected to the load output A.sub.n of power distribution system 1 or forming it. Switch latch 13 can, for example, also be manually actuated from the outside by means of a pushbutton or switch lever 16, therefore, for example, switched on or tripped (ON/OFF). Tripping device 12, switch latch 13, and switch contacts 14, 15 form as it were the electromechanical line or device circuit breaker of protective device GS.sub.m.

[0034] Protective device GS.sub.m has an electronic evaluation and tripping unit 17, which is referred to hereafter as switch electronics or simply as electronics and which is integrated into protective device GS.sub.m or assigned to the device as an electronic module, for example, also in a separate module housing. Electronics 17 is supplied with load current I.sub.L, as the actual current I.sub.act, flowing over tripping path 11 of protective device GS.sub.m and measured by a current sensor 18. The current measurement can occur contact-free and in particular inductively. In addition, electronics 17 is supplied with output voltage U.sub.AC of UPS power supply unit 2 as the actual voltage U.sub.act, the output voltage being detected between input E.sub.L and a further input E.sub.N of protective device GS.sub.m by means of a voltage measuring device 19.

[0035] The voltage supply to electronics 17 is effected by means of a power supply unit 20 in the form of an AC-DC converter (rectifier), which is connected to inputs E.sub.L and E.sub.N on the AC voltage side as well as to electronics 17 on the DC voltage side. Electronics 17 is also supplied in addition via inputs E.sub.1 and E.sub.2 with a load-specific or device-specific parameter P.sub.N, which indicates its rated load, and a parameter P.sub.max, characterizing the maximum load of UPS power supply unit 2, by the corresponding parameter input. Direct current parameters I.sub.A or I.sub.B can also be input into electronics 17.

[0036] The current value I.sub.A, resulting from the input of parameter P.sub.N or inputted directly, determines the position of an electronic overload characteristic curve K.sub.UE shown in FIG. 4 or a corresponding characteristic curve region of protective device GS.sub.m, whereas the input of the power supply-specific parameter P.sub.max or I.sub.B determines the position of an electronic short-circuit characteristic curve K.sub.K or a corresponding characteristic curve region for the UPS protection of UPS power supply 2. The characteristic curve regions K.sub.UE and K.sub.K form the electronic characteristic curve K.sub.E, shown in FIG. 4, or the corresponding characteristic curve region of the protective device GS.sub.m. The presetting using parameter P.sub.max or I.sub.B is suitably done using the data sheet for UPS power supply unit 2 with respect to the short-circuit current.

[0037] In the exemplary embodiment, electronics 17 supplies an indicator signal S.sub.A to an output A.sub.LED of the circuit breaker for controlling, for example, a luminous display (LED) or the like.

[0038] FIG. 3, in conjunction with the diagrams in FIG. 4, illustrates the tripping algorithm of protective device GS.sub.m, which has been implemented as software in electronics 17. FIG. 4 in the right half of the figure shows in a time-current diagram the course of the actual current I.sub.act which is typical for the switch-on characteristic curve of load 10. Between a power unit-specific rated and overload characteristic curve K.sub.UPS, typical for UPS power supply 2, with a rated and overload region K.sub.KSU (N) or K.sub.KSU (UE), and the course of actual current I.sub.act, an electronic characteristic curve K.sub.K of electronics 17 as a short-circuit region and an electronic characteristic curve K.sub.UE of electronics 17 as an overload region are each shown as dashed areas. The characteristic curve region K.sub.B with its thermal overload trip region A.sub.t and its magnetic short-circuit trip region A.sub.m illustrates the B-tripping characteristic of tripping device 12 of protective device GS.sub.m as line and/or device protection. The characteristic curve designated with I.sub.s represents the melting current of fuses 3 connected upstream of UPS power supply unit 2. The electronic characteristic curve K.sub.UE for the overload and the electronic characteristic curve K.sub.K of evaluation and tripping unit 17 of protective device GS.sub.m, the latter characteristic curve representing the maximum load P.sub.max, I.sub.B of UPS power supply 2 in the event of a short circuit, meet in the point designated by K.sub.KUE or the characteristic curve region or transitional region.

[0039] With the beginning (start) of the test cycle of the algorithm illustrated in FIG. 3, a comparison of the detected actual current I.sub.act and the current parameter I.sub.B giving the position of the UPS protection characteristic curve K.sub.UPS or the electronic characteristic curves K.sub.K for the short circuit region is made in or by electronics 17 on the basis of the implemented algorithm. In addition, a comparison can occur of the time profile of the actual voltage U.sub.act of the detected output voltage U.sub.AC of UPS power supply unit 2 with a voltage value U.sub.MIN derived from the parameter P.sub.max for the maximum load of UPS power supply unit 2 (U.sub.MIN=P.sub.Max/I.sub.B). U.sub.MIN can also be obtained from the DIN EN 62040-3 standard for the uninterruptible power supply and/or from the data sheet of UPS power supply unit 2.

[0040] If during a time interval t, illustrated in FIG. 4, for a maximum duration tt.sub.max, with, for example t.sub.max=1 ms, the detected actual current I.sub.act exceeds the characteristic curve region K.sub.K, K.sub.UPS, predetermined by the current parameter or current value I.sub.B, and hereby the detected actual voltage U.sub.act and thereby the output voltage U.sub.AC of UPS power supply unit 2 fall below the predetermined voltage or minimum value U.sub.MIN, protective device GS.sub.m is tripped by a corresponding opening of switch contacts 14, 15 as a result of a corresponding tripping (off) of tripping device 12, directly or indirectly, via switch latch 13, on the basis of a corresponding initiation by electronics 17. Otherwise, an uncritical operation designated by U is detected.

[0041] FIG. 4 shows the voltage-time curve of the detected actual value U.sub.act of the output voltage U.sub.AC in the left half of the figure as the characteristic curve of UPS power supply unit 2 in battery operation AB. During converter operation SB, or in the case of an optional changeover to bypass path 2b of UPS power supply unit 2, no voltage drop in the output voltage U.sub.AC of UPS power supply unit 2 would be expected during the time interval t and thus no falling of the actual voltage U.sub.act below the minimum or threshold value U.sub.MIN. The specified value U/U.sub.set=100% without a voltage drop in the time interval t represents the corresponding characteristic curve for converter operation or bypass operation.

[0042] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can also be derived herefrom by the skilled artisan, without going beyond the subject of the invention. Particularly, further all individual features described in relation to the exemplary embodiments can also be combined with one another in a different manner, without going beyond the subject of the invention. Thus, for example, the number of connected load circuits of power distribution system 1 can also be one (1).

[0043] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.