Multistage protective device for overcurrent- and overvoltage-protected transmission of electrical energy

Abstract

A protective device includes a first fuse circuit, an overvoltage protection circuit, and a second fuse circuit. The first fuse circuit prevents a flow of a line current from a voltage terminal to the electrical load when the line current reaches a first nominal current. The overvoltage protection circuit is connected downstream of the first fuse circuit and upstream of the electrical load, and is adapted to electrically connect two poles of the voltage terminal when a voltage at the voltage terminal reaches a first voltage limit to force the line current to the first nominal current such that the first fuse circuit is triggered. The second fuse circuit is connected downstream of the overvoltage protection circuit and upstream of the electrical load, and prevents flow of the line current when the line current reaches a second nominal current, wherein the second nominal current is based on the electrical load.

Claims

1. A protective device for overcurrent- and overvoltage-protected transmission of electrical energy from a voltage terminal to an electrical load, wherein the voltage terminal comprises two poles, the protective device comprising: a first fuse circuit adapted to prevent a flow of a line current from the voltage terminal to the electrical load when said line current reaches a first nominal current; an overvoltage protection circuit connected downstream of the first fuse circuit and upstream of the electrical load, wherein the overvoltage protection circuit is adapted to electrically connect the poles of the voltage terminal when a voltage at the voltage terminal reaches a first voltage limit to force the line current to the first nominal current such that the first fuse circuit is triggered; and a second fuse circuit connected downstream of the overvoltage protection circuit and upstream of the electrical load, wherein the second fuse circuit is adapted to prevent the flow of the line current when said line current reaches a second nominal current, wherein the second nominal current is based at least in part on the electrical load.

2. The protective device according to claim 1, wherein the first nominal current is a first prospective short-circuit current and the second nominal current is a second prospective short-circuit current, wherein the second nominal current is smaller than the first nominal current, and wherein the overvoltage protection circuit is adapted to reduce a nominal voltage of the second fuse circuit.

3. The protective device according to claim 1, wherein the second nominal current is smaller than the first nominal current such that a current flow with a correspondingly lower short-circuit current strength to the electrical load is prevented.

4. The protective device according to claim 1, wherein the overvoltage protection circuit comprises a semiconductor switch electrically connected in parallel to the poles of the voltage terminal, wherein the semiconductor switch comprises a control input and is adapted to electrically connect the poles of the voltage terminal based on a control signal applied to the control input, and wherein the semiconductor switch is further adapted to disconnect an electrical connection of the poles of the voltage terminal when the line current falls below a minimum current value.

5. The protective device according to claim 4, wherein the semiconductor switch comprises a thyristor or a transistor.

6. The protective device according to claim 1, wherein each of the first fuse circuit and the second fuse circuit comprises an overcurrent protective device comprising one or more of: a fuse or a power switch, and wherein each respective overcurrent protective device is adapted to disconnect an electrical connection between the voltage terminal and the electrical load based at least in part on one or more of: the first nominal current or the second nominal current being reached or an elapsed a predetermined time interval after reaching the first nominal current or the second nominal current.

7. The protective device according to claim 1, wherein the second fuse circuit has at least two current paths, wherein each current path is adapted to transmit electrical energy to a respective electrical load, wherein an overcurrent protective device is arranged in each of the respective current paths.

8. The protective device according to claim 7, wherein the overcurrent protective device of each current path is adapted to trigger at a different nominal current such to prevent a current flow in that respective current path.

9. The protective device according to claim 1, wherein one or more of the first fuse circuit or the second fuse circuit is adapted to detect one or more of a component temperature or ambient temperature, and wherein the one or more of the first fuse circuit or the second fuse circuit is further adapted, when the component temperature or the ambient temperature reaches a temperature limit, to trigger the overvoltage protection circuit or to prevent a current flow from the voltage terminal to the electrical load.

10. The protective device according to claim 1, wherein the second fuse circuit is adapted to provide the electrical load with a reduced maximum electrical power compared to a composite comprising the first fuse circuit and the overvoltage protection circuit by limiting the line current to the second nominal current.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further examples are explained with reference to the accompanying figures.

(2) FIG. 1 shows an example of a protective device; and

(3) FIG. 2 shows an example of a protective device.

DETAILED DESCRIPTION

(4) FIG. 1 shows a schematic representation of the protective device 100 for the overcurrent- and overvoltage-protected transmission of electrical energy from a voltage terminal 101 to an electrical load 103, wherein the voltage terminal 101 comprises two poles. The protective device 100 comprises a first fuse circuit 105, which is adapted to prevent the flow of a line current from the voltage terminal 101 to the electrical load 103 when said line current reaches a first nominal current strength limit.

(5) The protective device 100 further comprises an overvoltage protection circuit 107, which is connected downstream of the first fuse circuit 105 and upstream of the electrical load 103. The overvoltage protection circuit 107 is adapted to connect the poles of the voltage terminal 101 in an electrically conductive manner when a voltage reaches a first voltage limit at the voltage terminal 101, in order to force a line current which reaches the first nominal current to trigger the first fuse circuit 105.

(6) Furthermore, the protective device 100 comprises a second fuse circuit 109, which is connected downstream of the overvoltage protection circuit 107 and is connected upstream of the electrical load 103. The second fuse circuit 109 is adapted to prevent the line current from flowing when a second nominal current is reached by the line current. The second nominal current is smaller than the first nominal current.

(7) The overvoltage protection circuit 107 comprises a semiconductor switch 111, in particular a thyristor, which is connected electrically in parallel to the poles of the voltage terminal 101 and has a control input 113. The semiconductor switch 111 is adapted to connect the poles of the voltage terminal 101 in an electrically conductive manner with a control signal applied to the control input 113 and to cancel the electrical connection of the poles of the voltage terminal 101 when the line current falls below the minimum current value.

(8) The overvoltage device 107 further comprises a voltage limit switch 115, in particular a Z-diode with a switch input 117 and a switch output 119. The voltage limit switch 115 is connected downstream of the first fuse circuit 105 via the switch input 117 and is connected to the control input 113 of the semiconductor switch 111 via the switch output 119. Furthermore, the voltage limit switch 115 is adapted to provide the control signal at the switch output 119 when the first voltage limit is reached by the voltage at the voltage terminal 101.

(9) The overvoltage protection circuit 107 further comprises a resistor 121, which is connected downstream of the switch output 119 of the voltage limit switch 115 and is arranged with the voltage limit switch 115 electrically parallel to the poles of the voltage terminal 101. The control input 113 is connected to the switch output 119 of the voltage limit switch 115 and the resistor 121, the resistor 121 being adapted to provide a control signal, in particular in the form of part of the voltage at the voltage terminal 101, when the voltage limit switch 115 is switched to the control input 113, in order to switch the semiconductor switch 111.

(10) The first fuse circuit 105 and the second fuse circuit 109 each have an overcurrent protective device 123, 125, in particular a fuse. The overcurrent protective device 123 is adapted to disconnect the electrical connection between the voltage terminal 101 and the electrical load 103 when the first current strength limit is reached or to disconnect it after a predetermined time interval after the first nominal current has been reached. Correspondingly, the overcurrent device 125 is adapted to disconnect the electrical connection between the voltage terminal 101 and the electrical load 103 when the second nominal current is reached or after a predetermined time interval has passed after the second current strength limit has been reached.

(11) FIG. 2 shows a schematic representation of the protective device 100 for the transmission of electrical energy from a voltage terminal 101 to at least two electrical loads 103, 205. The protective device 100 comprises a first fuse circuit 105, which is adapted to prevent a flow of the line current when a first nominal current is reached by a line current from the voltage terminal 101 to the electrical loads 103, 205.

(12) The protective device 100 further comprises an overvoltage protection circuit 107, which is connected downstream of the first fuse circuit 105 and is connected upstream of the electrical loads 103, 205. The overvoltage protection circuit 107 is adapted to connect the poles of the voltage terminal 101 in an electrically conductive manner when a first voltage limit of a voltage at the voltage terminal 101 is reached, in order to force a line current which reaches the first nominal current to trigger the first fuse circuit 105.

(13) Furthermore, the protective device 100 comprises a second fuse circuit 109, which is connected downstream of the overvoltage protection circuit 107 and upstream of the electrical loads 103, 205. The second fuse circuit 109 has two current paths 201-1, 201-2, which are each adapted to transmit electrical energy to an electrical load 103, 205. An overcurrent protective device 125, 203 is arranged in each of the current paths 201-1, 201-2.

(14) The overcurrent protection fuse 125 is adapted to prevent the current from flowing through the current path 201-1 when a second nominal current of a current flow through the current path 201-1 is reached. The overcurrent protective devices 203 are adapted to prevent the current from flowing through the current path 201-2 when a third nominal current of a current flow through the current path 201-2 is reached. The second nominal current and the third nominal current can each be less than the first nominal current. The overcurrent protective devices 125, 203 are adapted to trigger at different nominal currents in order to prevent a current flow in the respective current path 201-1, 201-2.

LIST OF REFERENCE NUMBERS

(15) 100 protective device

(16) 101 voltage terminal

(17) 103 electrical load

(18) 105 first fuse circuit

(19) 107 overvoltage protection circuit

(20) 109 second fuse circuit

(21) 111 semiconductor switches

(22) 113 control input

(23) 115 voltage limit switch

(24) 117 switch input

(25) 119 switch output

(26) 121 resistance

(27) 123 overcurrent protective device

(28) 125 overcurrent protective device

(29) 201-1 current path

(30) 201-2 current path

(31) 203 overcurrent protective device

(32) 205 electrical load