CN102761096B - Undervoltage-overvolprotection protection device and method - Google Patents
Undervoltage-overvolprotection protection device and method Download PDFInfo
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- CN102761096B CN102761096B CN201110108560.5A CN201110108560A CN102761096B CN 102761096 B CN102761096 B CN 102761096B CN 201110108560 A CN201110108560 A CN 201110108560A CN 102761096 B CN102761096 B CN 102761096B
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Abstract
The present invention proposes a kind of Undervoltage-overvolprotection protection device.This protective device comprises: a tripping coil (210), is connected in supply line, for being in trip status when Line under-voltage; Over-voltage detection circuit (240), for producing overvoltage protection triggering signal when detecting that line voltage distribution exceedes predetermined threshold; Control device (250), in response to described overvoltage protection triggering signal, makes described tripping coil two ends under-voltage, thus described tripping coil performs trip action.Adopt this protective device can only use a tripping coil just can realize under-voltage, overvoltage double protection, thus reduce cost and greatly reduce the volume of protective device simultaneously.
Description
Technical Field
The invention relates to an undervoltage-overvoltage protection device and a method, in particular to a device and a method for undervoltage and overvoltage double protection by using a single trip coil.
Background
In general, the voltage on the power supply line is not a constant value, which may fluctuate accordingly due to changes in the load. Such voltage fluctuations (e.g., undervoltage or overvoltage) on the power supply lines can adversely affect or even damage the consumer if the voltage fluctuations exceed the range that the consumer can tolerate. Therefore, an under-voltage protection or an over-voltage protection device is usually adopted to ensure that the electric equipment is used in a normal power supply state.
Under-voltage protection generally refers to a protection device that automatically cuts off a power supply line when the voltage of the power supply line is below a predetermined threshold (e.g., below 80% of a nominal voltage), and that can be manually restored again until the line voltage returns to a normal range. In contrast, overvoltage protection means that when the line voltage exceeds a predetermined value (for example 10% above the nominal voltage), the protection device also automatically disconnects the line in order to prevent damage to the consumer, and can be manually restored again when the line voltage returns to normal.
The undervoltage-overvoltage protection device in the current market mainly adopts 2 discrete trip coils to respectively realize the detection and the protection action of undervoltage and overvoltage. Fig. 1 schematically illustrates a conventional undervoltage-overvoltage protection device 100. As shown in fig. 1, the power supply lines L (live line) and N (neutral line) are used to supply power to the consumer 150. The protection device 100 is disposed on the consumer side and includes two trip coils 110 and 120 and an overvoltage detection device 140. The two trip coils are respectively used for executing tripping action when undervoltage or overvoltage is detected. The tripping action of the trip coils 110 and 120 in turn mechanically drives the circuit breaker 130 to break the electrical connection of the power supply line to the electrical consumer 150.
Specifically, in fig. 1, both ends of the trip coil 110 are connected to the lines L and N. When the line voltage V is below a predetermined threshold Vmin (i.e. undervoltage), the push rod in the trip coil 110 is in position 2, i.e. tripped state, and thus the circuit breakers on lines L and N are in open state. When the line voltage V rises to the normal range, the push rod in the trip coil 110 shifts from position 2 to position 1, so that the circuit breaker 130 is closed and the line is conductive. Trip coil 120 is connected to an overvoltage detection circuit 140 for detecting whether the line voltage is over-voltage. When the overvoltage detection circuit 140 detects that the line voltage V is normal, the push rod in the trip coil 120 is at position 1, so that the circuit breaker 130 remains closed and the power supply line is turned on. When the overvoltage detection circuit 140 detects that the line voltage V exceeds a predetermined threshold Vmax, it outputs an overvoltage protection trigger signal, causing the push rod in the trip coil 120 to shift from position 1 to position 2, i.e., into a tripped state, which causes the circuit breakers 130 on lines L and N to disconnect the supply.
The structure shown in figure 1 can realize undervoltage and overvoltage double protection. However, as can be seen from fig. 1, the undervoltage-overvoltage protection device needs two independent trip coils to realize undervoltage protection and overvoltage protection respectively. Each trip coil is relatively large and costly due to its mechanical structure, especially compared to electronic components. This drawback obviously cannot meet the requirement of miniaturization and low cost of the current protection device. Therefore, further improvement is needed for the existing under-voltage and over-voltage protection device.
Disclosure of Invention
It is an object of the present invention to provide an undervoltage-overvoltage protection device and method that is small and low cost. Therefore, the invention provides a device and a method for realizing undervoltage-overvoltage double protection by using a single trip coil. The undervoltage-overvoltage protection device is obviously superior to the existing undervoltage-overvoltage protection device with double trip coils in volume and cost because only one trip coil is included.
In order to achieve the above object, the present invention provides an under-voltage/over-voltage protection device comprising: the trip coil is connected to the power supply circuit and is used for being in a trip state when the circuit is under-voltage; an overvoltage detection circuit for generating an overvoltage protection trigger signal when detecting that the line voltage exceeds a predetermined threshold; and the control device is used for responding to the overvoltage protection trigger signal to ensure that two ends of the trip coil are undervoltage, so that the trip coil executes tripping action. The protection device can realize undervoltage and overvoltage double protection by only using one trip coil, thereby reducing the cost and greatly reducing the volume of the protection device.
According to one aspect of the invention, the control device is a switching device connected in parallel with the trip coil and which is closed in response to the overvoltage protection trigger signal. Alternatively, the switching means may be a transistor, a field effect transistor, a thyristor or a valve, or any other controllable switching device.
According to yet another aspect of the invention, the undervoltage-overvoltage protection device preferably requires electrical isolation between the switching device and the overvoltage detection circuit. This has the advantage that it is possible to avoid causing undesired malfunctions or damages when the power supply of the trip coil is different from the power supply of the overvoltage detection circuit. Preferably, the galvanic isolation is achieved using optocouplers or relays.
According to another aspect of the invention, a switching device for shorting a trip coil in response to an over-voltage protection trigger signal may include two transistors. The two transistors are always switched on and off during operation, thereby ensuring that the trip coil is forcibly short-circuited by the switching device only in the event of an overvoltage. In addition, the overvoltage detection circuit may include a comparator, a voltage detection chip, or any other device that can determine an overvoltage.
The invention also provides an under-voltage and over-voltage protection method. The method comprises the following steps: using a trip coil, wherein the trip coil is in a trip state when a power supply line is undervoltage; detecting whether the line voltage exceeds a predetermined threshold; and when the line voltage is detected to exceed the preset threshold value, the tripping coil is enabled to execute tripping action due to undervoltage at two ends.
Preferably, the method further undervoltages the two ends of the trip coil by shorting the two ends of the trip coil. More preferably, the method further comprises electrically isolating the detecting operation and the undervoltage-applying operation from each other. The galvanic isolation is achieved, for example, using optocouplers or relays.
Drawings
The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein,
FIG. 1 shows a schematic diagram of a prior art undervoltage-overvoltage protection device;
fig. 2 schematically shows a structural view of an undervoltage-overvoltage protection device according to an embodiment of the present invention;
FIG. 3 illustrates a circuit schematic of an undervoltage-overvoltage protection device according to one embodiment of the present invention;
fig. 4 shows a circuit schematic of an undervoltage-overvoltage protection device according to yet another embodiment of the invention.
Description of reference numerals:
100 existing under-voltage-over-voltage protection device
110 trip coil
120 trip coil
130 circuit breaker
140 overvoltage detection circuit
150 electric appliance device
130 circuit breaker
200 under-voltage-over-voltage protection device
240 overvoltage detection circuit
250 control device
300 undervoltage-overvoltage protection device
340 overvoltage detection circuit
350 switching device
360 optical coupler
400 under-voltage-over-voltage protection device
440 overvoltage detection circuit
450 switching device
460 relay circuit
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings.
Fig. 2 schematically illustrates a schematic diagram of an undervoltage-overvoltage protection device 200 according to an embodiment of the invention. As shown in fig. 2, the protection device 200 according to an embodiment of the present invention includes a single trip coil 210, an overvoltage detection circuit 240, and a control device 230. The trip coil 210 of the protection device 200 is capable of driving the circuit breaker 130 to open or close the power supply connection when the trip operation is performed. Only one trip coil 210 is used in the protection device 200 to control the circuit breakers 130 (e.g., the main contacts of the miniature circuit breaker MCB) on lines L and N. When undervoltage occurs, the trip coil 210 performs a trip action and causes the circuit breaker 130 to break the power supply connection in a manner similar to the trip coil 110 of fig. 1. When overvoltage occurs, the trip coil 210 is tripped due to undervoltage by the driving of the overvoltage detection circuit 240 and the control device 250, so that the circuit breaker 130 is disconnected from the power supply. Thus, only one trip coil can be used in the invention to realize the double protection of undervoltage and overvoltage.
Specifically, in fig. 2, both ends of the trip coil 210 are connected to the lines L and N on the electric equipment side. When the line voltage V, i.e., the voltage across the trip coil 210, is below a predetermined threshold Vmin, the push rod in the trip coil 210 is in position 2, i.e., tripped, causing the circuit breaker 130 on the line to remain open and the power supply to be interrupted. When the line voltage V (the voltage across the trip coil 210) reaches or exceeds the predetermined threshold Vmin, the push rod in the trip coil 210 shifts to position 1, so that the circuit breaker 130 on the line is closed and the power supply line is conductive. If the line voltage V drops below Vmin again after the line is turned on, the trip coil 210 enters the trip state as described above, thereby implementing the under-voltage protection.
For an overvoltage condition, it is detected by the overvoltage detection circuit 240 of fig. 2 whether the line voltage V exceeds a predetermined threshold Vmax. If so, the over-voltage detection circuit 240 outputs an over-voltage protection trigger signal to the controller 250. The controller 250, in response to this trigger signal, causes the voltage across the trip coil 210 to drop below the threshold Vmin (i.e., to an under-voltage state), causing the trip coil 210 to trip due to the under-voltage. This tripping action of the trip coil 210 in turn causes the circuit breaker 130 on the line to open, thereby providing overvoltage protection.
With the protection device 200 shown in fig. 2, the dual functions of under-voltage and over-voltage protection can be realized only by a single trip coil 210, so that the size and cost of the protection device 200 can be reduced to meet the current miniaturization requirement.
In fig. 2, the over-voltage detection circuit 240 and the controller 250 can be implemented by various means. For example, the control device 250 may be a switch device that can be closed in response to the over-voltage protection trigger signal of the over-voltage detection circuit 240, i.e., the two ends of the trip coil 210 are brought into an under-voltage state due to a short circuit. Optionally, the control device 240 may also drop the voltage across the trip coil 210 below Vmin through a triggerable voltage conversion circuit (e.g., a voltage transformation device). In addition, the control device 250 may also be implemented using other triggerable voltage step-down circuits known to those skilled in the art.
Fig. 3 shows a circuit diagram of an undervoltage-overvoltage protection device 300 according to an embodiment of the invention. In the protection device 300, the trip coil 210 is a low-voltage coil, the control device 250 is implemented as a switching device 350, and the overvoltage detection circuit 340 is implemented as a voltage detection chip U3. The switching device 350 is implemented, for example, by a combination of transistors Q1 and Q2. In addition, an isolation device 360, such as an optical coupler, is added between the over-voltage detection circuit 340 and the switching device 350 to provide electrical isolation between the under-voltage protection and the over-voltage protection.
Specifically, as shown in fig. 3, in one branch, a rectified (U1) line voltage V1 is applied across trip coil L1 (210). When the line voltage V1 is lower than a threshold voltage Vmin, the trip coil L1 is tripped, and further causes the circuit breaker 130 (not shown in fig. 3) to open, thereby implementing the under-voltage protection.
In the other branch of fig. 3, the rectified (U4) line voltage V2 is applied across voltage dividing resistors R3-R6. The voltage detecting chip U3 (alternatively, a comparator) obtains the divided voltage V3 from the resistor R6 and compares it with a threshold voltage Vmax. If the comparison result is that V3 is greater than Vmax, then U3 outputs an over-voltage protection trigger signal, such as a high level, at its output terminal 4. This high signal is applied to the base of transistor Q3, which is connected in series with the led in optocoupler U5, to turn on Q3. The conduction of the Q3 causes the light emitting diode in the U5 to operate, the corresponding photosensitive semiconductor transistor is conducted, and the output terminal (V4) of the optocoupler U5 outputs a low level to the switch device 350. Conversely, if the comparison result is that V3 is less than Vmax, i.e., no overvoltage is present, then U3 outputs a low level at its output terminal 4. This low level turns off Q3, which in turn causes the optocoupler to be inoperative, i.e. the photosensitive transistor of optocoupler U5 is off and V4 is high. Thus, the overvoltage protection trigger signal generated by the overvoltage detection circuit is transmitted to the switching device 350 in an electrically isolated manner by the optocoupler U5.
In the example of fig. 3, the switching device 350 is composed of Q1 and Q2. Wherein the base of Q1 is connected to the output V4 of the optocoupler U5, and the base of Q2 is connected to the collector of Q1 and to the line voltage V1 via a resistor R12. Therefore, when V4 is high (no overvoltage occurs), Q1 is turned on, Q2 is turned off, and the trip coil L1 operates normally. When V4 is low (overvoltage protection triggered), Q1 is off and Q2 is on. At this time, since Q2 is turned on, the two ends of the trip coil L1 are forcibly short-circuited, so that the trip coil L1 is tripped due to undervoltage, and the circuit breaker 130 is further caused to disconnect the power supply connection, thereby realizing overvoltage protection.
In the example shown in fig. 3, the switching device 350 is implemented using a transistor. However, it will be appreciated by those skilled in the art that the switching means may also be implemented using, for example, field effect transistors, thyristors, valves, relays, etc. Furthermore, the optocoupler for electrical isolation shown in fig. 3 may also be replaced by other electrical isolation devices, such as a magnetic coupling or a relay.
Fig. 4 schematically shows an example of using a relay to act as an electrical isolation device in fig. 3. Unlike fig. 3, in fig. 4, electrical isolation between the switching device 450 and the over-voltage detection circuit 440 is achieved by a relay circuit 460.
Specifically, in one branch, rectified line voltage V1 is applied across trip coil L1 (210). Similar to before, the trip coil L1 performs a trip action when the V1 is undervoltage, and in turn causes the circuit breaker 220 to open.
In the other branch, the rectified voltage V2 is applied to the series branch of the voltage dividing resistors R2 and R3, so that the voltage detecting chip U5 obtains the divided voltage V3 from the resistor R2. The voltage detection chip U5 compares V3 with a predetermined threshold Vmax. If V3 is less than Vmax, then U5 outputs a low level indicating that no overvoltage is present. If the comparison result is that V3 is greater than Vmax, then U5 outputs a high level, i.e., an over-voltage protection trigger signal.
At the same time, the rectified voltage V2 is applied to the series branch of resistors R4, R5 and zener diode D10 to power the relay circuit 460 from D10. The relay circuit 460 includes a relay K1 and a transistor Q1 connected in series, the base of Q1 being connected to the output of U5. When the output of the U5 is low, the Q1 is cut off, so that the branch where the relay K1 is located is kept open, the relay K1 does not work, and the switching device 450 is kept open. When the U5 outputs a high level (an overvoltage protection trigger signal), the Q1 is turned on, so that the relay K1 is energized and the trigger switch device 450 is closed. That is, in response to the overvoltage protection trigger signal of the overvoltage detection circuit 440, the switching device 450 is driven by the relay K1 to trip the trip coil 210 due to the short circuit between the two ends, so that the circuit breaker 130 is opened, and overvoltage protection is realized.
In the example shown in fig. 4, relay K1 acts as an electrical isolation device between the overvoltage detection circuit 440 and the switching device 450. However, it will be appreciated by those skilled in the art that other means known in the art (e.g., magnetic coupling, etc.) may be used to achieve this electrical isolation.
As shown in fig. 2 to 4, the protection devices 200, 300, and 400 of the present invention are formed according to a design concept that a single trip coil is used to make the trip coil in a trip state when the power supply line is under-voltage; detecting whether the voltage on the line exceeds a predetermined threshold; when the line voltage is detected to exceed the preset threshold value, the two ends of the tripping coil are under-voltage, and therefore the tripping coil executes tripping action. Preferably, the two ends of the trip coil are under-voltage by short-circuiting the two ends of the trip coil. More preferably, the detecting operation and the operation of undervoltage-rendering both ends of the trip coil are electrically isolated from each other. Such electrical isolation is achieved, for example, using optocouplers or relays.
The design idea provided by the invention can ensure that under-voltage and over-voltage dual protection can be realized under the condition of only being suitable for a single trip coil, so that the design idea can reduce the volume of the under-voltage-over-voltage protection device and is suitable for the current miniaturization requirement. Meanwhile, the design idea is simple and convenient to realize and can be realized only by using low-cost electronic elements, so that the volume is reduced, and the equipment cost is also reduced.
It should be understood that although the present description has been described in terms of various embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and those skilled in the art will recognize that the embodiments described herein may be combined as suitable to form other embodiments, as will be appreciated by those skilled in the art.
The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations can be made by those skilled in the art without departing from the spirit and principles of the invention.
Claims (6)
1. An undervoltage-overvoltage protection device comprising:
the single trip coil (210) is connected to the power supply line and is in a trip state when the line is under-voltage;
an overvoltage detection circuit (240, 340) for generating an overvoltage protection trigger signal upon detection of a line voltage exceeding a predetermined threshold;
control means (250, 350) for undervoltage across said trip coil in response to said overvoltage protection trigger signal, whereby said trip coil performs a trip action;
wherein the control means (250, 350) is a switching means (350) connected across the trip coil and which is closed in response to the over-voltage protection trigger signal;
the switch device (350) is electrically isolated from the overvoltage detection circuit (340) by an optical coupler (360).
2. The protection device of claim 1, wherein the switching device (350) comprises any one of a triode, a field effect transistor, a thyristor, a valve, and a relay.
3. The protection device of claim 2, wherein the switching device (350) comprises two transistors (Q1, Q2), a first transistor (Q1) having a base for receiving the over-voltage protection trigger signal, a second transistor (Q2) having a base connected to a collector of the first transistor and to a power supply via a resistor, and a collector and an emitter of the second transistor (Q2) being connected across the trip coil (210), respectively.
4. The protection device of claim 1, wherein the overvoltage detection circuit (340) comprises a comparator or a voltage detection chip.
5. The protection device of claim 1, wherein the trip coil (210) is a low voltage coil.
6. A method of performing under-voltage-over-voltage protection, comprising:
using a single trip coil, wherein the trip coil is in a trip state when a power supply line is undervoltage;
detecting whether the line voltage exceeds a predetermined threshold;
when the line voltage is detected to exceed the preset threshold value, the two ends of the trip coil are under-voltage through short-circuiting the two ends of the trip coil, so that tripping action is executed; and,
and the detection operation and the operation of undervoltage at two ends of the trip coil are mutually electrically isolated through an optical coupler.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201110108560.5A CN102761096B (en) | 2011-04-28 | 2011-04-28 | Undervoltage-overvolprotection protection device and method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201110108560.5A CN102761096B (en) | 2011-04-28 | 2011-04-28 | Undervoltage-overvolprotection protection device and method |
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| Publication Number | Publication Date |
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| CN102761096A CN102761096A (en) | 2012-10-31 |
| CN102761096B true CN102761096B (en) | 2015-10-14 |
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| CN105207171B (en) * | 2015-09-21 | 2018-02-06 | 余姚市嘉荣电子电器有限公司 | Earth leakage protective device powers on/off control circuit automatically |
| CN105305796A (en) * | 2015-10-12 | 2016-02-03 | 重庆凯瑞电动汽车系统有限公司 | Frequency converter direct-current busbar overvoltage and under-voltage protection method and system |
| ES2694563T3 (en) * | 2016-03-14 | 2018-12-21 | Abb S.P.A. | A coil actuator for LV or MV applications |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4788621A (en) * | 1987-12-16 | 1988-11-29 | General Electric Company | Molded case circuit breaker multiple accessory unit |
| CN201163720Y (en) * | 2008-02-18 | 2008-12-10 | 李德恒 | Multi-use household electrical appliance protector capable of automatic trip when power-on after power-off |
| CN201422010Y (en) * | 2009-03-13 | 2010-03-10 | 朱大利 | Power consumption protector with overvoltage under-voltage protection and time-delay function |
| CN201717601U (en) * | 2010-07-30 | 2011-01-19 | 郑天翼 | Power supply failure shunt trip and overvoltage, under-voltage protection miniature circuit breaker |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090237187A1 (en) * | 2006-09-21 | 2009-09-24 | Daniel Gawendowicz | Auxiliary release for a circuit breaker |
| CN201425994Y (en) * | 2009-05-27 | 2010-03-17 | 中山市开普电器有限公司 | Power plug with leakage protection function |
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2011
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4788621A (en) * | 1987-12-16 | 1988-11-29 | General Electric Company | Molded case circuit breaker multiple accessory unit |
| CN201163720Y (en) * | 2008-02-18 | 2008-12-10 | 李德恒 | Multi-use household electrical appliance protector capable of automatic trip when power-on after power-off |
| CN201422010Y (en) * | 2009-03-13 | 2010-03-10 | 朱大利 | Power consumption protector with overvoltage under-voltage protection and time-delay function |
| CN201717601U (en) * | 2010-07-30 | 2011-01-19 | 郑天翼 | Power supply failure shunt trip and overvoltage, under-voltage protection miniature circuit breaker |
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