CA1292772C - Device for monitoring the operation readiness of an electrical installation - Google Patents
Device for monitoring the operation readiness of an electrical installationInfo
- Publication number
- CA1292772C CA1292772C CA000550569A CA550569A CA1292772C CA 1292772 C CA1292772 C CA 1292772C CA 000550569 A CA000550569 A CA 000550569A CA 550569 A CA550569 A CA 550569A CA 1292772 C CA1292772 C CA 1292772C
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- monitoring
- light
- resistor
- display element
- switching device
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Abstract
Abstract:
The subject of the invention is a device for monitoring the operational readiness of an electrical installation in which a load is connected via a switching device to a DC, AC or three-phase supply, and also for monitoring the switching device.
A first monitoring circuit (2) is connected in parallel with the switching unit (1) and contains a first display element (LED 1, LED 2), while a second monitoring circuit (3) containing a second display element (LED 3, LED 4), is connected on the one hand to the branch of the circuit joining the switching device (1) and the electrical load (4) and on the other hand with the voltage supply source.
The subject of the invention is a device for monitoring the operational readiness of an electrical installation in which a load is connected via a switching device to a DC, AC or three-phase supply, and also for monitoring the switching device.
A first monitoring circuit (2) is connected in parallel with the switching unit (1) and contains a first display element (LED 1, LED 2), while a second monitoring circuit (3) containing a second display element (LED 3, LED 4), is connected on the one hand to the branch of the circuit joining the switching device (1) and the electrical load (4) and on the other hand with the voltage supply source.
Description
lZ9Z~'7Z
Device for monitoring the operation readiness of an electrical ~nstallation The invention relates to a device for monitoring the operational readiness of an electrical installation in which a load is connected via a switching device with a DC, AC or three-phase current supply. The device also monitors the statùs of the switching device.
It is known that electrical machinery or industrial equipment can be connected via cutout boxes, containing switches and/or fusible electrical links, to an AC or three-phase supply system. However, these known types of cutout boxes do not contain any means for displaying the operational readiness of the electrical machinery or industrial equipment, nor do they display the switching status of the associated cutout, so that in the event of failure of one or more cutouts it is not apparent whether and if so which cutout has been activated.
In addition, in the known types of cutout boxes, it is not apparent whether power is being supplied to the electrical load, i.e. to the electrical machinery or industrial equipment, or not; consequently it is not possible to say whether the equipment or machinery in question is operationally ready or not.
Therefore, if the operation of industrial equipment or of an electrical machine is interrupted, a complicated fault-tracing procedure has to be carried out in order to determine whether the power supply has been disrupted, whether one or more cutouts have been activated or whether there is a defect in the equipment or machinery.
A further problem encountered with the known types of cutout boxes is that if a fuse has to be replaced in the box, additional measuring instruments are needed to determine whether the respective power connection has been isolated or not.
lZ927`7Z
U~ Patent 4 641 120 describes an optoelectrical display ~evice for electrical fuses which permits a simple and reliable display of the switching status of the fuse, so tnat i~ can be recognized whether the electrical circuit is ope-~.ionally ready or has been interrupted. However, if this known type of optoelectrical display device is fitted to a fuse element in order to indicate the latter's status, it is not possible to determine that status if the fuse and display are mounted inside a closed, non-transparent cutout box. In addition, the known type of optoelectrical display gives no indication whether the fuse element in question has been electrically isolated or not. If the circuit is open, or if the fuse has been activated, the optoelectrical display will light up only if the displacement current flowing via the open cable is strong enough, i.e. if the capacitive resistance of the cable is small enough. This requirement is met only if the cable is sufficiently long.
In addition, the known type of fuse can be used only in AC
voltage grids.
US Patent 4 148 024 describes an electrical fuse arranged in a liquid-tight housing which can be immersed in water. The status of the fuse is displayed by an externally arranged neon lamp. The outer surface of the housing and most of the interior surface of the housing is covered with an electrically conducting coating. A thin, annular band of semi-conducting coating material is arranged between the terminals of the fuse device on the inner surface of the housing, so that once the fuse is activated the voltage difference at the fuse terminals is capacitively transmitted through the housing to the display lamp. The latter responds to a change in voltage and periGdically lights up to display the activation of the fuse.
lZ~Z~7'7Z
However, this known type of display device also fails to indicate when the fuse element has been electrically isolated, consequently when there is no power at the load it is not possible to determine, without using additional S measuring devices, whether the fuse is still under power or whether it has been activated.
German Offenlegungsschrift DE - A - 21 10 706 describes a display device for electrical fuses in which a glow lamp is connected in parallel to each fuse. If the fusible element in the fuse device in question melts, the glow lamp lights up. In addition, a common photovoltaic cell coupled with an evaluation device is assigned to a group of several glow lamps, so that in the event of failure of a fuse a group display is given. The glow lamps and photovoltaic cells are arranged in a closed light-proof housing. This known type of display device also is incapable of indicating whether a circuit has been electrically isolated and does not function in an open circuit.
In addition, it is disadvantageous that the display is not given at the site of the fuse elements furthermore, this display device is very complex because of the necessary glow lamps and photovoltaic cells and a great deal of space is needed to house all these various elements.
German Offenlegungsschrift DE - A - 35 15 773 describes a device for monitoring fuses in which a high-ohmic resistor, consisting of a ballast resistor with parallel resistance, a set of rectifiers, and on the DC side a zener diode with protective rectifier, are connected in parallel with a fuse element. The counter voltage is supplied to an optocoupler whose output is connected with an auxiliary power source and a transistorized switching unit consisting of switching transistors used to transmit the operating status of the fuse elements. This known type of monitoring circuit does not function in the case of an open circuit or when the lZ9Z7'72 power supply connection is electrically isolated; and furthermore, because of t'ne electronic switching components it is relatively complicated, and because o-f the number of components needed, most of which have to possess particularly high electrical strength, it is very expensive It is the purpose of the present invention to eliminate the aforementioned disadvantages and to describe a monitoring device which indicates reliably and in an easily recognizable manner both the operational readiness of an electrical load and the status of a s~itching device for electrical equipment, even if the circuit is open and short leads are used.
This task is solved by means of a monitoring device containing a first monitoring circuit which is connected in parallel to the switching device, and a first display element, as well as a second monitoring circuit which is connected on the one hand to the branch of the circuit linking the switching device with the electrical load, and on the other hand to the other terminal of a power supply system, and which contains a second display element.
The monitoring device according to the invention is capable of displaying, reliably and in a clearly recognizable manner, on the one hand the operational readiness of an electrical installation and on the other hand the switching status for example of an electrical fuse used to protect the electrical installation when the circuit is open and when short lengths of wire are involved. As a result, the monitoring device is suitable, for example, also for motor ciruit breakers in which the voltage supply to the electrical load is cut off immediately behind fuse element.
A further advantage of the monitoring device according to the invention is that it requires few components, so that it is not expensive to produce a display unit for indicating operational and switching statuses. This is of significance l;~9Z7'~2 especially in the case of large-scale production.
An advantageous refinement of the invention consists in that the display elements are connected in parallel to the switching device or the fuse or to the branch between the fuse elements and S the terminals of the electrical load, via a simple printed resistive circuit, preferably of thick film design. The display elements consist preferentially of light-emitting diode elements with two anti-parallel connecte(~ light-emitting diodes, so that in conjunction with a printed resistive circuit of thick film design a simple, robust and space-saving monitoring device is created.
In a further advantageous refinement of the invention, one of the anti-parallel connected light-emitting diodes may be part of an optocoupler which can be additionally used to transmit the status of the fuse.
The compact design of the monitoring device and the use of simple and robust components makes it possible to arrange the monitoring device as a hybrid circuit on a substrate and to embed it in casting resin if needed in order to make a display module, so that this module is also capable of withstanding large electrical and mechanical stresses and is suitable, for example, for use in damp environments.
In another preferred refinement of the invention the display module is mounted in or on a recess in the cover of a switching cabinet or box, so that in addition to having a pleasing appearance it offers the user greater safety and is better protected against possible damage.
129Z7'72 In another advantageous refinement of the invention, an acoustical signal can be used instead of or in addition to an optical display, so that for example the status of the switching device can ~e optically or acoustically indicated, while the operating status is only optically displayed. In similar fashion, light-emitting diodes of different colours may be used as the display elements; in this case, for example, a blown fuse is indicated by a red light-emitting diode while the operational readiness of an electrical installation is indicated by a green light-emitting diode, thereby signalling that there is power at the electrical installation.
In various applications it may prove advantageous to use capacitive elements instead of ohmic resistive ele~ents or printed resistive circuits of thick film design. It is furthermore advantageous to integrate the capacitive elements or ohmic resistors into the light-emitting diodes which are used as the display elements.
In order to test the first display element it may be advantageous to provide a test button which, if the switch device is not open, will open a switch arranged in series to the second resistor and thus permit a check to be carried out on the light-up function of the display element.
When it is closed, a second switch arranged in parallel to the second display element will prevent the operational status of the installation from being displayed, while retaining the advantage that even if the load is switched off and short conductors are involved, the first display element will light up if the switch device is opened.
Advantageous refinements of the invention are identified in the sub-claims or are described in detail below together with the description of the preferred embodiment of the invention as shown in the Figures. The Figures are as follows:
lZ~Z~'72 Figure 1: A monitoring devicQ for an electrical load connected to a DC or AC supply.
Figure 2: A monitoring device for an electrical load connected to a three-phase supply.
Figure 3: A monitoring device as per Figure 1 with two switches for checking the function of the display elements or for switching off the operating status display.
Figure 1 shows a circuit used for the monitoring device of a load 4, which may consist of an electric machine, an electric arc furnace, or a welding machine, or similar, and which is connected via a protective fuse element 1 to a voltage-carrying phase of a DC or AC supply.
A first monitoring circuit 2 is connected in parallel to the fuse element l; this monitoring circuit consists of a first resistor Rl connected in series with two anti-parallel connected light-emitting diodes LED 1, LED 2 and a second resistor R2, the resistance of which must be very small in comparison with the resistance of the first resistor Rl. Depending upon the load and the supply network, the second resistor R2 can be replaced by a short-circuit in some cases.
A second monitoring circuit 3 is connected on the one hand to the branch between the two anti-parallel connected light-emitting diodes LED 1, LED 2 and the second resistor R2, and on the other hand to the earth ground, chassis ground or reference potential of the single-phase supply; this second monitoring circuit consists of two anti-parallel connected light-emitting diodes LED
3, LED 4 connected in series with a third resistor R3 which is connected to the chassis ground or reference potential.
In this embodiment of the invention the light-emitting diode LED
4 is part of an optoelectronic coupler 5 and serves as the radiation-emittin~ element, whose radiation is received by a phototransistor ~4 as the radiation receiver. Instead of a phototransistor as a radiation receiver, it is of course also lZ927'72 possible to use a photodiode or a Darlington transistor.
Optionally, the base terminal of the phototransistor T 4 can also be extended so that the collector-base pathway is used as a photodiode while the emitter of the phototransistor remains unconnected. The phototransistor T 4 amplifies the ,ohotodiode current according to its current-amplifying capacity, so that wnen the single-phase supply is applied a corresponding confirmatory signal regarding the operational readiness can be transmitted.
The optoelectronic coupler can be designed as a monolithic integrated optocoupler, so that a particularly space-saving and functionally reliable arrangement is created to monitor the operational status.
The resistors R 1, R2, R 3 are preferentially produced as printed resistive circuits of thick film design and they can be integrated into the light-emitting diodes.
Instead of the resistors it is also possible to use capacitors, preferably of thick film type, or as surface mounted devices.
In order to create a mechanically and electrically robust monitoring device the entire monitoring circuit, consisting of the first and second monitoring circuit 2, 3, can be arranged as a hybrid circuit on a substrate element. In addition, this monitoring module can be potted in casting resin, with three leads projecting from the module; these leads are connected to the terminals of fuse element 1 and to the chassis ground or reference potentials.
Instead of the leads projecting from the module, it is also possible to use a multi-pin self-aligning plug.
1292~72 g Another possible variant consists of integrating the first and second resistors Rl, R2 into the leads of the monitoring module.
IE one or more of the light-emitting diodes are used as the radiation-emitting element of an optoelectronic coupler, then an appropriate number of extra leads are brought out of the resin-potted module to transmit the status of the fuse or the operational status. The two wires projecting from the potted module fo~ attachment to the fuse element 1 are connected by screwing them down under the connector terminals of the respective fuse holder In operation, when voltage is being applied to the load 4, the anti-parallel connected light-emitting diodes LED 3, LED 4 of the second monitoring circuit 3 light up or the optocoupler 5 transmits a corresponding operational status signal to a remote lS monitoring device.
If fuse element 1 has been activated, for example because of a short-circuit current, then light-emitting diodes LED 1, LED 2 in the first monitoring circuit 2 will come on and indicate that the associated fuse element 1 has cut out. In this way, if the operation of the electrical load 4 is interrupted, a simple fault diagnosis can be made because the second monitoring circuit 3 indicates whether voltage is still being supplied from the single-phase source. At the same time, this operational display can be used to indicate the status of switching elements connected ahead of the fuse. Also, if an electrical load 4 connected directly behind the fuse has been shut down, the light-emitting diodes LED 1, LED 2 of the first monitoring circuit 2 will light up if the associated fuse element 1 has cut out.
Figure 2 shows a monitoring device for a three-phase electrical 3~ load 40, which for example might be an electric machine, 1~927'7Z
connected to a three-phase supply having the phases R, S, T.
Like the single-phase monitoring device shown in Fig. 1, first monitoring circuits 21, 22, 23 are connected in parallel to the fuse elements 11, 12, 13 arranged in the three phases of the three-phase supply; these circuits each consist of a first resistor 1, two anti-parallel connected light-emitting diodes LED
1, LED 2 and a second resistor R2 connected in series.
Second monitoring circuits 31, 32, 33, consisting of two anti-parallel connected light-emitting diodes LED 3, LED 4 and a third resistor R3 all connected in series, are connected to the branch of the circuit linking the anti-parallel connected light-emitting diodes LEn 1, LE~ 2 to the second resistors R2.
The third resistors R3 of the second monitoring circuits 31, 32, 33 are electrically interconnected in such a way that when the three phases of the three-phase supply are energized, the lignt-emitting diodes LRD 3, LED 4 of the second monitoring circuits 31, 32, 33 light up.
If one or more of the fuse elements 11, 12, 13, is activated, then the associated light-emitting diodes LED 1, LED 2 in the first monitoring circuits 21, 22, 23 will also light up and signal that the fuse in question has been activated.
Also in this embodiment oE the invention, an optoelectronic coupler can be used instead of a light-emitting diode, so that the status of the individual fuse elements 11, 12, 13 and also the operating status of the load can be remotely transmitted.
Alternatively, or additionally, an acoustical signalling device can be used which is triggered, for example, when a fuse element is activated.
A further variant consists of using red light-emitting diodes as display elements for the first monitoring circuit 21, 22, 23 to monitor the status of the fuse, while green light-emitting diodes are used as display elements for the second monitoring circuits 31, 32, 33 to indicate the operating status; these green LEDs light up if voltage from the supply source is being applied to the electrical load 40.
In these embodiments of the invention it is also possible to use printed resistive circuits, preferentially of thick film design, or capacitive elements, as resistors; the entire monitoring device can be arranged in a hybrid circuit on a substrate or it can be potted in casting resin to form a display module.
Figure 3 shows a variant of the nonitoring device as per Figure 1; identical reference nuMbers identify identical parts, so that the description of Figure 1 applies in this case as well.
In addition, in this embodiment a first switch 6 is provided in series to the second resistor R2; this switch is connected with a test button, which is not described in any further detail, and is closed in the neutral position. Operating the test button opens first switch 6 and thus permits the functional capability of the first display element LED 1, LED 2 to be checked even if the switching device has not opened, i.e. for example the fuse has not been activated.
A second switch 7 is provided to switch off the display of the operating status of the installation; this switch is connected in parallel to the second display element LED 3, LED 4 and in the closed state it short circuits the second display element LED 3, LED 4 and causes the operational status display to be extinguished. Wevertheless, the advantageous characteristic of the invention is retained, in that namely even when the load 4 is switched off and short leads are used, tne first display element lights up if the switching device is opened, i.e. a fuse element is activated.
Tne monitoring device according to the invention is suitable not only for installation in new equipment but it can also be used to retrofit existing equipment because the operational status and fuse status display can be very compactly designed and integrated into existing equipment.
The scope of the invention is not limited to the above-mentioned preferred embodiment. Instead, a large number of variants are conceivable which can make use of the solution presented here, even in fundamentally different desic3n configurations.
Device for monitoring the operation readiness of an electrical ~nstallation The invention relates to a device for monitoring the operational readiness of an electrical installation in which a load is connected via a switching device with a DC, AC or three-phase current supply. The device also monitors the statùs of the switching device.
It is known that electrical machinery or industrial equipment can be connected via cutout boxes, containing switches and/or fusible electrical links, to an AC or three-phase supply system. However, these known types of cutout boxes do not contain any means for displaying the operational readiness of the electrical machinery or industrial equipment, nor do they display the switching status of the associated cutout, so that in the event of failure of one or more cutouts it is not apparent whether and if so which cutout has been activated.
In addition, in the known types of cutout boxes, it is not apparent whether power is being supplied to the electrical load, i.e. to the electrical machinery or industrial equipment, or not; consequently it is not possible to say whether the equipment or machinery in question is operationally ready or not.
Therefore, if the operation of industrial equipment or of an electrical machine is interrupted, a complicated fault-tracing procedure has to be carried out in order to determine whether the power supply has been disrupted, whether one or more cutouts have been activated or whether there is a defect in the equipment or machinery.
A further problem encountered with the known types of cutout boxes is that if a fuse has to be replaced in the box, additional measuring instruments are needed to determine whether the respective power connection has been isolated or not.
lZ927`7Z
U~ Patent 4 641 120 describes an optoelectrical display ~evice for electrical fuses which permits a simple and reliable display of the switching status of the fuse, so tnat i~ can be recognized whether the electrical circuit is ope-~.ionally ready or has been interrupted. However, if this known type of optoelectrical display device is fitted to a fuse element in order to indicate the latter's status, it is not possible to determine that status if the fuse and display are mounted inside a closed, non-transparent cutout box. In addition, the known type of optoelectrical display gives no indication whether the fuse element in question has been electrically isolated or not. If the circuit is open, or if the fuse has been activated, the optoelectrical display will light up only if the displacement current flowing via the open cable is strong enough, i.e. if the capacitive resistance of the cable is small enough. This requirement is met only if the cable is sufficiently long.
In addition, the known type of fuse can be used only in AC
voltage grids.
US Patent 4 148 024 describes an electrical fuse arranged in a liquid-tight housing which can be immersed in water. The status of the fuse is displayed by an externally arranged neon lamp. The outer surface of the housing and most of the interior surface of the housing is covered with an electrically conducting coating. A thin, annular band of semi-conducting coating material is arranged between the terminals of the fuse device on the inner surface of the housing, so that once the fuse is activated the voltage difference at the fuse terminals is capacitively transmitted through the housing to the display lamp. The latter responds to a change in voltage and periGdically lights up to display the activation of the fuse.
lZ~Z~7'7Z
However, this known type of display device also fails to indicate when the fuse element has been electrically isolated, consequently when there is no power at the load it is not possible to determine, without using additional S measuring devices, whether the fuse is still under power or whether it has been activated.
German Offenlegungsschrift DE - A - 21 10 706 describes a display device for electrical fuses in which a glow lamp is connected in parallel to each fuse. If the fusible element in the fuse device in question melts, the glow lamp lights up. In addition, a common photovoltaic cell coupled with an evaluation device is assigned to a group of several glow lamps, so that in the event of failure of a fuse a group display is given. The glow lamps and photovoltaic cells are arranged in a closed light-proof housing. This known type of display device also is incapable of indicating whether a circuit has been electrically isolated and does not function in an open circuit.
In addition, it is disadvantageous that the display is not given at the site of the fuse elements furthermore, this display device is very complex because of the necessary glow lamps and photovoltaic cells and a great deal of space is needed to house all these various elements.
German Offenlegungsschrift DE - A - 35 15 773 describes a device for monitoring fuses in which a high-ohmic resistor, consisting of a ballast resistor with parallel resistance, a set of rectifiers, and on the DC side a zener diode with protective rectifier, are connected in parallel with a fuse element. The counter voltage is supplied to an optocoupler whose output is connected with an auxiliary power source and a transistorized switching unit consisting of switching transistors used to transmit the operating status of the fuse elements. This known type of monitoring circuit does not function in the case of an open circuit or when the lZ9Z7'72 power supply connection is electrically isolated; and furthermore, because of t'ne electronic switching components it is relatively complicated, and because o-f the number of components needed, most of which have to possess particularly high electrical strength, it is very expensive It is the purpose of the present invention to eliminate the aforementioned disadvantages and to describe a monitoring device which indicates reliably and in an easily recognizable manner both the operational readiness of an electrical load and the status of a s~itching device for electrical equipment, even if the circuit is open and short leads are used.
This task is solved by means of a monitoring device containing a first monitoring circuit which is connected in parallel to the switching device, and a first display element, as well as a second monitoring circuit which is connected on the one hand to the branch of the circuit linking the switching device with the electrical load, and on the other hand to the other terminal of a power supply system, and which contains a second display element.
The monitoring device according to the invention is capable of displaying, reliably and in a clearly recognizable manner, on the one hand the operational readiness of an electrical installation and on the other hand the switching status for example of an electrical fuse used to protect the electrical installation when the circuit is open and when short lengths of wire are involved. As a result, the monitoring device is suitable, for example, also for motor ciruit breakers in which the voltage supply to the electrical load is cut off immediately behind fuse element.
A further advantage of the monitoring device according to the invention is that it requires few components, so that it is not expensive to produce a display unit for indicating operational and switching statuses. This is of significance l;~9Z7'~2 especially in the case of large-scale production.
An advantageous refinement of the invention consists in that the display elements are connected in parallel to the switching device or the fuse or to the branch between the fuse elements and S the terminals of the electrical load, via a simple printed resistive circuit, preferably of thick film design. The display elements consist preferentially of light-emitting diode elements with two anti-parallel connecte(~ light-emitting diodes, so that in conjunction with a printed resistive circuit of thick film design a simple, robust and space-saving monitoring device is created.
In a further advantageous refinement of the invention, one of the anti-parallel connected light-emitting diodes may be part of an optocoupler which can be additionally used to transmit the status of the fuse.
The compact design of the monitoring device and the use of simple and robust components makes it possible to arrange the monitoring device as a hybrid circuit on a substrate and to embed it in casting resin if needed in order to make a display module, so that this module is also capable of withstanding large electrical and mechanical stresses and is suitable, for example, for use in damp environments.
In another preferred refinement of the invention the display module is mounted in or on a recess in the cover of a switching cabinet or box, so that in addition to having a pleasing appearance it offers the user greater safety and is better protected against possible damage.
129Z7'72 In another advantageous refinement of the invention, an acoustical signal can be used instead of or in addition to an optical display, so that for example the status of the switching device can ~e optically or acoustically indicated, while the operating status is only optically displayed. In similar fashion, light-emitting diodes of different colours may be used as the display elements; in this case, for example, a blown fuse is indicated by a red light-emitting diode while the operational readiness of an electrical installation is indicated by a green light-emitting diode, thereby signalling that there is power at the electrical installation.
In various applications it may prove advantageous to use capacitive elements instead of ohmic resistive ele~ents or printed resistive circuits of thick film design. It is furthermore advantageous to integrate the capacitive elements or ohmic resistors into the light-emitting diodes which are used as the display elements.
In order to test the first display element it may be advantageous to provide a test button which, if the switch device is not open, will open a switch arranged in series to the second resistor and thus permit a check to be carried out on the light-up function of the display element.
When it is closed, a second switch arranged in parallel to the second display element will prevent the operational status of the installation from being displayed, while retaining the advantage that even if the load is switched off and short conductors are involved, the first display element will light up if the switch device is opened.
Advantageous refinements of the invention are identified in the sub-claims or are described in detail below together with the description of the preferred embodiment of the invention as shown in the Figures. The Figures are as follows:
lZ~Z~'72 Figure 1: A monitoring devicQ for an electrical load connected to a DC or AC supply.
Figure 2: A monitoring device for an electrical load connected to a three-phase supply.
Figure 3: A monitoring device as per Figure 1 with two switches for checking the function of the display elements or for switching off the operating status display.
Figure 1 shows a circuit used for the monitoring device of a load 4, which may consist of an electric machine, an electric arc furnace, or a welding machine, or similar, and which is connected via a protective fuse element 1 to a voltage-carrying phase of a DC or AC supply.
A first monitoring circuit 2 is connected in parallel to the fuse element l; this monitoring circuit consists of a first resistor Rl connected in series with two anti-parallel connected light-emitting diodes LED 1, LED 2 and a second resistor R2, the resistance of which must be very small in comparison with the resistance of the first resistor Rl. Depending upon the load and the supply network, the second resistor R2 can be replaced by a short-circuit in some cases.
A second monitoring circuit 3 is connected on the one hand to the branch between the two anti-parallel connected light-emitting diodes LED 1, LED 2 and the second resistor R2, and on the other hand to the earth ground, chassis ground or reference potential of the single-phase supply; this second monitoring circuit consists of two anti-parallel connected light-emitting diodes LED
3, LED 4 connected in series with a third resistor R3 which is connected to the chassis ground or reference potential.
In this embodiment of the invention the light-emitting diode LED
4 is part of an optoelectronic coupler 5 and serves as the radiation-emittin~ element, whose radiation is received by a phototransistor ~4 as the radiation receiver. Instead of a phototransistor as a radiation receiver, it is of course also lZ927'72 possible to use a photodiode or a Darlington transistor.
Optionally, the base terminal of the phototransistor T 4 can also be extended so that the collector-base pathway is used as a photodiode while the emitter of the phototransistor remains unconnected. The phototransistor T 4 amplifies the ,ohotodiode current according to its current-amplifying capacity, so that wnen the single-phase supply is applied a corresponding confirmatory signal regarding the operational readiness can be transmitted.
The optoelectronic coupler can be designed as a monolithic integrated optocoupler, so that a particularly space-saving and functionally reliable arrangement is created to monitor the operational status.
The resistors R 1, R2, R 3 are preferentially produced as printed resistive circuits of thick film design and they can be integrated into the light-emitting diodes.
Instead of the resistors it is also possible to use capacitors, preferably of thick film type, or as surface mounted devices.
In order to create a mechanically and electrically robust monitoring device the entire monitoring circuit, consisting of the first and second monitoring circuit 2, 3, can be arranged as a hybrid circuit on a substrate element. In addition, this monitoring module can be potted in casting resin, with three leads projecting from the module; these leads are connected to the terminals of fuse element 1 and to the chassis ground or reference potentials.
Instead of the leads projecting from the module, it is also possible to use a multi-pin self-aligning plug.
1292~72 g Another possible variant consists of integrating the first and second resistors Rl, R2 into the leads of the monitoring module.
IE one or more of the light-emitting diodes are used as the radiation-emitting element of an optoelectronic coupler, then an appropriate number of extra leads are brought out of the resin-potted module to transmit the status of the fuse or the operational status. The two wires projecting from the potted module fo~ attachment to the fuse element 1 are connected by screwing them down under the connector terminals of the respective fuse holder In operation, when voltage is being applied to the load 4, the anti-parallel connected light-emitting diodes LED 3, LED 4 of the second monitoring circuit 3 light up or the optocoupler 5 transmits a corresponding operational status signal to a remote lS monitoring device.
If fuse element 1 has been activated, for example because of a short-circuit current, then light-emitting diodes LED 1, LED 2 in the first monitoring circuit 2 will come on and indicate that the associated fuse element 1 has cut out. In this way, if the operation of the electrical load 4 is interrupted, a simple fault diagnosis can be made because the second monitoring circuit 3 indicates whether voltage is still being supplied from the single-phase source. At the same time, this operational display can be used to indicate the status of switching elements connected ahead of the fuse. Also, if an electrical load 4 connected directly behind the fuse has been shut down, the light-emitting diodes LED 1, LED 2 of the first monitoring circuit 2 will light up if the associated fuse element 1 has cut out.
Figure 2 shows a monitoring device for a three-phase electrical 3~ load 40, which for example might be an electric machine, 1~927'7Z
connected to a three-phase supply having the phases R, S, T.
Like the single-phase monitoring device shown in Fig. 1, first monitoring circuits 21, 22, 23 are connected in parallel to the fuse elements 11, 12, 13 arranged in the three phases of the three-phase supply; these circuits each consist of a first resistor 1, two anti-parallel connected light-emitting diodes LED
1, LED 2 and a second resistor R2 connected in series.
Second monitoring circuits 31, 32, 33, consisting of two anti-parallel connected light-emitting diodes LED 3, LED 4 and a third resistor R3 all connected in series, are connected to the branch of the circuit linking the anti-parallel connected light-emitting diodes LEn 1, LE~ 2 to the second resistors R2.
The third resistors R3 of the second monitoring circuits 31, 32, 33 are electrically interconnected in such a way that when the three phases of the three-phase supply are energized, the lignt-emitting diodes LRD 3, LED 4 of the second monitoring circuits 31, 32, 33 light up.
If one or more of the fuse elements 11, 12, 13, is activated, then the associated light-emitting diodes LED 1, LED 2 in the first monitoring circuits 21, 22, 23 will also light up and signal that the fuse in question has been activated.
Also in this embodiment oE the invention, an optoelectronic coupler can be used instead of a light-emitting diode, so that the status of the individual fuse elements 11, 12, 13 and also the operating status of the load can be remotely transmitted.
Alternatively, or additionally, an acoustical signalling device can be used which is triggered, for example, when a fuse element is activated.
A further variant consists of using red light-emitting diodes as display elements for the first monitoring circuit 21, 22, 23 to monitor the status of the fuse, while green light-emitting diodes are used as display elements for the second monitoring circuits 31, 32, 33 to indicate the operating status; these green LEDs light up if voltage from the supply source is being applied to the electrical load 40.
In these embodiments of the invention it is also possible to use printed resistive circuits, preferentially of thick film design, or capacitive elements, as resistors; the entire monitoring device can be arranged in a hybrid circuit on a substrate or it can be potted in casting resin to form a display module.
Figure 3 shows a variant of the nonitoring device as per Figure 1; identical reference nuMbers identify identical parts, so that the description of Figure 1 applies in this case as well.
In addition, in this embodiment a first switch 6 is provided in series to the second resistor R2; this switch is connected with a test button, which is not described in any further detail, and is closed in the neutral position. Operating the test button opens first switch 6 and thus permits the functional capability of the first display element LED 1, LED 2 to be checked even if the switching device has not opened, i.e. for example the fuse has not been activated.
A second switch 7 is provided to switch off the display of the operating status of the installation; this switch is connected in parallel to the second display element LED 3, LED 4 and in the closed state it short circuits the second display element LED 3, LED 4 and causes the operational status display to be extinguished. Wevertheless, the advantageous characteristic of the invention is retained, in that namely even when the load 4 is switched off and short leads are used, tne first display element lights up if the switching device is opened, i.e. a fuse element is activated.
Tne monitoring device according to the invention is suitable not only for installation in new equipment but it can also be used to retrofit existing equipment because the operational status and fuse status display can be very compactly designed and integrated into existing equipment.
The scope of the invention is not limited to the above-mentioned preferred embodiment. Instead, a large number of variants are conceivable which can make use of the solution presented here, even in fundamentally different desic3n configurations.
Claims (20)
1. A device for monitoring the operational readiness of an electrical installation in which a load is connected via a switching device to a DC voltage or AC voltage supply, and also for monitoring the status of the switching device, characterized by a first monitoring circuit connected in parallel with the switching device and containing a first display element consisting of two anti-parallel connected light-emitting diodes, and a second monitoring circuit connected on one hand to a branch linking the switching device and the load and on the other hand to another terminal of the voltage supply and containing a second display element consisting of two anti-parallel connected light-emitting diodes, wherein the monitoring circuits include at least one resistor connected in series with the anti-parallel connected light-emitting diodes, and wherein the monitoring circuits each take the form of a hybrid circuit formed on a common substrate.
2. A device according to claim 1, wherein the supply is a three-phase supply.
3. A device according to claim 1 or 2, characterized in that at least one of the two anti-parallel connected light-emitting diodes is the light-emitting element of an optocoupler, a light-receiving part of which is connected with a line for transmitting the status of the display element.
4. A device according to claim 1, characterized in that the first display element is connected via a first resistor with one terminal of the switching device and via a second resistor with the other terminal of the switching device, and further the second display element is connected on one hand with a branch between the first display element and the second resistor, while on the other hand it is connected via a third resistor with a terminal of the voltage supply.
5. A device according to claim 2, characterized in that the first display element is connected via a first resistor with one terminal of the switching device and via a second resistor with the other terminal of the switching device, and further the second display element is connected on one hand with a branch of the circuit linking the associated first display element with the second resistor and on the other hand is connected via a third resistor with the second display element.
6. A device according to claim 4 or 5, wherein the resistors consist of printed circuits.
7. A device according to claim 4 or 5, wherein the resistors consist of capacitive elements.
8. A device according to claim 1 or 2, wherein by the fact that the monitoring circuits are arranged in a monitoring module which is potted in resin.
9. A device according to claim 1 or 2, wherein the monitoring circuits are arranged in a monitoring module which is potted in resin, and connecting leads projecting from the potted monitoring module are connected to terminals of the switching device.
10. A device according to claim 1 or 2, wherein the monitoring circuits are arranged in a monitoring module which is potted in resin, and the monitoring module is connected to a multi-pin, self-aligning plug.
11. A device according to claim 1 or 2, wherein the monitoring circuits are arranged in a monitoring module which is potted in resin, and the first and second resistors are integrated into the connecting wire of the monitoring module.
12. A device according to claim 1 or 2, wherein the display elements each consist of an acoustical signal device.
13. A device according to claim 1 or 2, wherein the display elements each consist of an acoustical signal device, the acoustical signal devices being connected in parallel to the light-emitting diodes.
14. A device according to claim 1 or 2, wherein the display elements each consist of an acoustical signal device, wherein the acoustical signal devices being connected in series with the light-emitting diodes.
15. A device according to claim 1 or 2, wherein the first and second display elements consist of light-emitting diodes of different colours.
16. A device according to claim 4 or 5, wherein the resistors consist of integrated components.
17. A device according to claim 1 or 2, wherein each switching device consists of a protective element or fuse element.
18. A device according to claim 4 or 5, wherein a first switch is arranged between the second resistor and the branch linking the switching device and the load, this switch being openable by means of a test button to test the functional capability of the first display element.
19. A device according to claim 4 or 5, wherein a second switch is connected in parallel with the second display element.
20. A device according to claim 1 or 2, wherein the light-emitting element of an optocoupler is connected in series with at least one of said first display elements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000550569A CA1292772C (en) | 1987-10-29 | 1987-10-29 | Device for monitoring the operation readiness of an electrical installation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000550569A CA1292772C (en) | 1987-10-29 | 1987-10-29 | Device for monitoring the operation readiness of an electrical installation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1292772C true CA1292772C (en) | 1991-12-03 |
Family
ID=4136750
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000550569A Expired - Lifetime CA1292772C (en) | 1987-10-29 | 1987-10-29 | Device for monitoring the operation readiness of an electrical installation |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1292772C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109917281A (en) * | 2018-09-14 | 2019-06-21 | 中船重工西安东仪科工集团有限公司 | It is a kind of for testing the device and method of slip ring action sequence |
-
1987
- 1987-10-29 CA CA000550569A patent/CA1292772C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109917281A (en) * | 2018-09-14 | 2019-06-21 | 中船重工西安东仪科工集团有限公司 | It is a kind of for testing the device and method of slip ring action sequence |
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