DE69619367T3 - CONTROL PROCESS AND DEVICE FOR SWITCH DRIVE - Google Patents

Description

BACKGROUND THE INVENTION

1. Subject area the invention

The The present invention relates to an apparatus for controlling an electrical switching device. More specifically, it refers the invention relates to a device for controlling a switching device, which is a voice coil actuator used to quickly and positively open a circuit breaker and close.

2. Description of in Related prior art:

In a power distribution system, a switching device in the System for a number of reasons be installed to, for example, an automatic protection abnormal load conditions to achieve or open and Shut down of sections of the system. Different types a switching device comprise a switch for selectively opening and Shut down a power transmission line, such as a line to a capacitor bank; one Error interrupter for automatically opening a line on the Detection of an error; and a recloser that turns quickly, upon detection of a fault, a predetermined one Number of times opens and close, until either the fault is eliminated or the reclosing switch locked in an open position.

Vacuum interrupter have been widely used in the art since Do a quick low energy arc interruption with a long one Contact life, low mechanical stress and a high degree of operational reliability. In a vacuum breaker the contacts are sealed in a vacuum envelope. One of Contacts is a movable contact having an actuator that extends through a vacuum seal in the enclosure.

SUMMARY AND TASKS

A The object of the present invention is to provide a shifter actuator mechanism and a controller for it to create an arcing and generated transitions during an opening and closing minimize.

A Another object of the present invention is to provide a switch motion element mechanism and a controller for it to create an accurate monitoring of the system.

A Another object of the present invention is to provide a switch actuator mechanism to create that for a range of motion profiles is suitable, thereby the Need to eliminate many types of mechanical systems.

A Another object of the present invention is to provide a shifter actuator mechanism which is capable of doing so by any conventionally available Motor control circuit or an associated motion control circuit to be controlled.

A Still another object of the present invention is a shifter actuator mechanism to create, suitable for the achievement of speeds and forces that does not work with mechanical systems of the prior art can be achieved.

A Still another object of the present invention is to provide an improved, synchronously working switching device to create that one significant reduction of transients generated during the Switchover, leads.

Generally has a switching device that uses vacuum interrupters, different spring-loaded mechanisms used with an actuator are connected to positively open the breaker contacts or close. A such device, the usual is used is a simple rocker joint. The primary function of these mechanisms is the one that makes bowing by very fast Driving the contacts to their open or closed positions to minimize. Various applications can use a number spring-loaded mechanisms with associated latches and require connections.

To build these mechanical systems, either by compression or expansion of the drive spring, an actuator is normally provided. These actuators may include, but are not limited to, solenoids, motors, or hydraulic devices. Compared to the specific speed requirements of the breaker to effectively interrupt a current, these actuators are relatively slow with poor response times. For this reason, they are normally used to drive the breaker contacts directly, but are not used to build up the fast acting spring mechanisms. The fundamental disadvantage of this Systems is that the spring-operated process itself does not lead to being easily controllable, and it requires a considerable engineering effort to finely adjust the operation of the mechanism.

In In practice, this means that many different mechanisms have to be interpreted to the different operating requirements for switches, fault interrupters and reclosing facilities and within each of these classes of switching devices There are different mechanisms depending on required by the application, including voltage and current requirements.

Farther is, in terms of high voltages, typically in Energy applications are used, a fast and accurate movement the breaker contacts desired, around an arcing between the contacts and the generation of transients to minimize. Dependent on from the application it can, whether there is now a capacitor bank switching or a spring break is, by professionals on the subject Be determined when the most advantageous time to Open breaker contact or close occurs. This optimal time correlates to a precise point on the voltage or current wave, where a power interruption or contact production will produce minimal arcing and transients would. Because conventional, spring-driven mechanisms do not themselves to that degree lead fine control, For example, this invention provides a viable means to provide a Point on the shaft or to achieve a synchronous switching. Such a synchronous operation of the breaker is both in terms of on the reduced wear of the breaker contacts as well with regard to the substantial reduction of general transient phenomena that by the energy system on the output side of the switching device unit occur, beneficial.

One Another feature of a controlled, synchronously operating switching device unit is that the speed under which the contacts shut down, can be controlled. In conventional systems, the Contacts together in an uncontrolled manner under one it is possible that very high speed is driven The contacts jump up several times until they come to rest. This rebound phenomenon is not wanted, because the resulting arcing can soften the contacts and strong welds can generate when the contacts finally match.

The DE-A-1640586 presents the next State of the art to the present invention.

According to the present Invention, a circuit breaker is provided as in claim 1 is defined.

The above features and advantages of the present invention from the following, more detailed description of the invention become apparent. The attached Drawings listed below are in explaining the invention useful.

In In the text that follows, the invention will be described with reference to FIG Embodiments shown in which:

1 FIG. 12 is a schematic diagram of a switching device employing a voice coil actuator; FIG.

2 FIG. 12 illustrates a cross-sectional view of one embodiment of a switching device; FIG.

3 shows a cross-sectional view of the vacuum module, shown in FIG 2 ;

4 FIG. 10 is an enlarged view of the operating mechanism of the embodiment shown in FIG 2 ,

5 Fig. 10 is an exploded view of the primary components of the actuating mechanism;

6 Fig. 12 is a graph showing the system voltage versus time and the dielectric decrease of the breaker;

7 shows a schematic view of a circuit that can be used in connection with the present invention;

8th Figure 9 is a graph showing a motion profile that may be used in conjunction with the present invention;

9 Fig. 12 is an illustration of a voice coil actuator that may be used in conjunction with the present invention;

10 shows a view of a locking mechanism that can be used in connection with the present invention;

11 Figure 11 is a view of a contact pressure spring mechanism that may be used in conjunction with the present invention;

12 FIG. 12 is a graph showing the synchronous timing of an opening operation of a capacitor switch. FIG.

DETAILED DESCRIPTION OF THE INVENTION

For a better one understanding The invention may be referred to the following detailed description taken in conjunction with the accompanying drawings is made, with preferred, exemplary embodiments of the Present invention described and described. Each reference number is consistent throughout the drawings.

In 1 is an incoming power supply line 2 in series with a circuit breaker 4 connected to allow the circuit breaker 4 the line opens. The administration 2 may be opened under a predetermined command, or, in the case of an error breaker, if an error exceeds a predetermined threshold level. One of the contacts of the circuit breaker 4 is with one end of an actuating rod 6 connected. The other end of the operating rod 6 is operational with a voice coil actuator 8th connected. The voice coil actuator 8th acts directly on the actuating rod 6 one to the contacts of the circuit breaker 4 to open or close.

The voice coil actuator 8th is a direct-drive, limited-motion device that has a magnetic field and a coil winding 10 used to generate a force proportional to the current applied to the coil. The electromechanical transformation of the voice coil actuator 8th is determined by the Lorentz force principle, which means that when a current carrying conductor is placed in a magnetic field, a force will act on it. The magnitude of the force is determined by the equation: F = kBLIN where F is the force, k is a constant, B is the magnetic flux density, L is the length of the conductor, I is the current in the conductor, and N is the number of turns of the conductor.

The current flowing through the voice coil winding 10 passes through a control mechanism 12 controlled. Any commercially available control mechanism 12 could be used. For example, suitable control mechanisms include 12 Single-loop controllers, programmable logic controllers or distributed control systems. The control mechanism 12 can with a feedback device 14 coupled to an input with respect to the position of the actuating rod 6 supplies.

The control mechanism 12 can also use a locking device 16 be coupled. When instructed, the operating rod 6 through the control mechanism 12 secure, fasten the locking device 16 the operating rod 6 in their position. In an alternative device, the locking mechanism 16 a permanent magnet or a mechanical interlock that is not compatible with the control device 12 is coupled.

In 2 a cross-sectional view of one of the embodiments of the invention is shown. A one-piece, elongated, firmly isolated encapsulation 18 encloses the operating rod 6 and the circuit breaker 4 , The encapsulation 18 may be formed of a ceramic, a porcelain, any suitable epoxy, or any other suitable solid insulating material. A line side, high voltage electrical connection 22 and a load side, high voltage electrical connection 20 stand over the tightly insulated envelope 18 before and are with the circuit breaker 4 connected. The high voltage electrical connections 20 and 22 are arranged diametrically 180 degrees apart and are parallel with each other. The encapsulation 18 provides both the solid insulation between the high voltage electrical connections 20 and 22 as well as the solid insulation between each high voltage electrical connection 20 and 22 and an electrical ground (not shown).

The circuit breaker 4 includes a vacuum module or a bottle 24 , shown in cross-section in FIG 3 , with a pair of switch contacts 71 . 72 , located inside the vacuum module 24 , The vacuum module 24 forms a housing and an evacuated environment for the operation of the pair of switch contacts. The module 24 is usually of an elongated, substantially tubular, evacuated ceramic housing 73 , preferably formed from aluminum oxide, constructed. One of the switching contacts 71 is movable, and the other switching contact 72 is stationary or fixed.

A special fitting 76 is on the shaft of the stationary contact 72 attached what the associated high voltage electrical connection 22 allows to exit at an angle of 90 °.

The movable switching contact 71 is at the uppermost longitudinal end of the actuating rod 6 attached. One method of attachment is that of a bolt 32 screwed into a tapered out made connection 74 in the moving shaft 75 of the movable contact 71 to use. When the switch contacts are in the closed position, as shown, a low resistance or electrical path in the form of a short circuit between the high voltage electrical terminals becomes 20 and 22 generated. The circuit breaker 4 further comprises a current exchange arrangement and an interface 26 between the vacuum module 24 and the power exchange arrangement. The current exchange arrangement includes a moving piston 28 and a fixed, outer housing 30 , In this embodiment, the actuating rod is 6 made of an electrically insulated material.

The other end of the operating rod 6 is on a flange 34 on the voice coil actuator 8th through a solid pin 36 secured. The pencil 36 that retains the protruding components in place may be secured by any suitable means, such as a pair of retaining rings. A recirculating, linear ball bearing 38 and split rings 40 , which hold the ball bearing, lead to a smooth movement of the actuating rod 6 , The voice coil winding 10 is between the outer body of the voice coil actuator 8th and the flange 34 arranged. side flanges 42 are on the outer body of the voice coil actuator 8th attached and connect with side beams 44 to thereby secure the voice coil actuator 8th on a protective housing 46 to fix. The protective housing 46 is on a lid 50 for the protective housing 46 over housing flanges 48 attached and the protective housing cover 50 is with the solid insulation cladding 18 over lid flanges 52 connected. As well as the solid, isolated encapsulation 18 is also the protective housing 46 ceramic, porcelain, any suitable epoxy, or any other suitable solid insulating material.

In this embodiment, the feedback device is 14 a position sensor, such as a linear potentiometer 14 , The linear potentiometer 14 can be constructed of a three-terminal rheostat or a resistor with one or more adjustable sliding contacts, thereby functioning as an adjustable voltage divider. The linear potentiometer 14 provides information regarding the position of the actuating rod 6 to the control mechanism 12 that controls the voice coil actuator 8th controls. Alternatively, the recirculation device 14 be an optical encoding.

The locking device 16 is intended to the operating rod 6 to secure. The locking device may be a controllable device, such as a solenoid, or a simple, mechanical or permanent magnetic lock comprising: a locking magnet 54 , a spacer 56 , made of a non-iron material, a screw 58 that the locking magnet 54 on the protective housing cover 50 secures, a locking plate 60 made of a steel or iron, and a locking plate pin 62 who has the locking plate 60 on the operating rod 6 guaranteed.

To better understand the invention, should be on the 4 and 5 Be referred. 4 FIG. 10 is an enlarged view of the actuating mechanism of the preferred embodiment shown in FIG 2 , dar., and 5 FIG. 4 illustrates an exploded view of the primary components of the actuating mechanism. FIG.

details, relating to the control mechanism of the present invention, will now be described.

6 provides a voltage signal 100 , plotted on a graph comparing the voltage level v (t) versus time t. In a 60 Hz application, every half cycle is ideally 8.33 ms. However, actual cycles may vary due to harmonics or asymmetric states, so a given half cycle may be greater or less than 8.33 ms.

Ideally, to minimize arcing and generation of transients in a capacitor switch application, the breaker contacts are closed instantaneously at zero points when v (t) is equal to zero. See point A in 6 , However, since the contacts can not close instantaneously, the timing of the initiation of the opening and closing sequences should be carefully controlled to minimize transients and arcing.

A preferred embodiment of a control circuit 200 for use in connection with the present invention is in 7 shown. The heart of the control circuit 200 is a microprocessor 202 which is suitable for use in a wide temperature range.

The voltage waveform of the power supply line passing through the breaker 4 is controlled with a voltage waveform analyzer 204 a phase locked loop circuit 206 and a V _ZERO continuity _{detection circuit} 208 analyzed. Information concerning the voltage waveform of the line to be interrupted, including the time The sense of zero points A, where the voltage v (t) is zero, becomes the microprocessor 202 entered. Alternatively, a voltage waveform analyzer could be used 204 be used, the voltage waveform directly from the line without the phase-locked loop circuit 206 measures.

Open and close commands become the microprocessor 202 via inputs 210 and 212 each entered. The open and close commands may be generated manually, may be initiated by a clock at preset times, may be initiated by external control, or may be triggered by the detection of an error, depending on the particular application of the breaker 4 ,

A reset signal 214 can go to the microprocessor 202 be entered to manually change the microprocessor 202 reset if necessary. For example, if the breaker 4 is manually manipulated, the microprocessor 202 not on the current status of the breaker 4 be set. In such a situation, the microprocessor should 202 be reset.

Status indicators can be provided to different states of the circuit 200 or the breaker 4 display. Such indicators can be a maintenance light 216 to indicate when maintenance is required, a power on light 218 , an indicator 220 for an open switch, an indicator 222 for a closed switch and a counter 224 , which can be used to count cycles or operations of the system.

A preferred embodiment of the present invention may include two control systems. A first control system is conventional and therefore not disclosed in detail herein, and determines when the line is controlled by the breaker 4 , should be opened or closed. The first control system may include an error detector or a timer for interrupting the line upon detecting an error or at a predetermined time.

Alternatively, an open or close command may be entered directly to the system. The open and close commands, whether they are from the first control system or have a manual origin, become the microprocessor 202 at entrances 210 and 212 each entered.

The second control system 200 represented in 7 , analyzes the voltage waveform of the line and determines the best timing to initiate opening and closing of the breaker 4 to minimize transients and arcing.

Every breaker 4 has a dielectric strength that defines the likelihood of an arc jump from one contact to the other. Dielectric strength depends on a number of factors, including the medium within the breaker 4 and the distance between the contacts 71 . 72 , 6 represents the change or decrease in dielectric strength between the contacts 71 . 72 versus time as the distance between the contact closures. See line C in 6 , Ideally, the dielectric strength between the contacts would be infinite until the exact moment of closing the contacts 71 . 72 , See line B in 6 , In reality, the dielectric runs obliquely downwards, decreasing rapidly as the contacts approach each other. See line C in 6 , If the slope of the dielectric waste is sufficiently high and the dielectric strength remains greater than the voltage of the waveform, the generation of arcing and overshoot operations is eliminated or substantially reduced.

Another factor that must be considered during the operation of a breaker is the relative speed between contacts during opening and closing. As the contacts move slowly, the slope of the dielectric waste will be low and arcing will likely occur. Conversely, if the contacts move too fast, especially when closing, the contacts will spring away from each other, causing unnecessary arcing and transients. Accordingly, a unique, ideal motion profile may exist for each application of a breaker. 8th represents an example of a motion profile in which the abscissa represents the position of the motion contact 71 represents and the ordinate represents the speed under which the contact 71 emotional. The point 0 on the abscissa represents the start or the maximum open position of the contact 71 and the point x represents the closed position with the contact 71 the stationary contact 72 touched. At point 0, when the close command is initiated, the speed is zero. The speed is increased as fast as possible up to a maximum speed V _max . The velocity remains at V _{max for} as long as possible, but it is reduced as the point of a contact approaches x to minimize springback.

During an opening sequence, the motion profile is also important to prevent the occurrence of reignites or reignitions shortly after opening. When the Disconnect contacts at too slow a speed or at the time the voltage level is too high, excessive arcing may occur. Desired motion profiles for opening and closing sequences may be determined by those skilled in the art and in the circuit 200 be preprogrammed.

It will become the 12 With reference to the timing of the opening operation in the application of a capacitor switching can be better understood. 12 refers to the opening sequence of a system comprising a capacitor bank. The administration 4 shows the voltage level of the fully charged capacitors. The switch starts at the point 2 to open and an arc forms. However, at this point, the current drops and the arc becomes zero at a current, point 3 , triggered. The system voltage is now at its peak, but the voltage across the contacts is small due to the charge on the capacitor bank approaching the peak system voltage. When the system voltage begins to drop, the voltage on the capacitor bank remains high, resulting in an increase in the voltage across the contacts. The contacts should be a part of sufficient acceleration so that the dielectric increases faster than the voltage between the contacts increases to avoid flashbacks or reignitions.

The motion control function may be accomplished by software loaded into the microprocessor / microcontroller, or by the addition of appropriate motion control chips interfacing with the microprocessor. A particular motion profile is programmed into a memory containing a separate EEPROM chip in an external motion control circuit 226 , or may be a built-in memory on the microprocessor or microcontroller. The motion control circuit 226 is with a feedback device (encoder) 14 and with a pulse width modulation (PWM) circuit 228 connected. The PWM 228 controls the current supplied to the voice coil actuator 8th is created. Because the force that the voice coil actuator 8th drives, proportional to the current supplied to the voice coil actuator 8th , is, is the speed of the actuator 6 (and motion contact 71 ) through the PWM 228 controlled. As a result, the voice coil actuator 8th controlled by a closed-loop feedback system comprising the position encoder 14 comprising a position signal of the actuating element 8th to the motion control circuit 226 sends. The motion control circuit 226 compares the actual position of the actuator 8th with the ideal motion profile, preprogrammed into the motion control circuit 226 into it. Based on comparing the actual position with the ideal motion profile, the voice coil actuator becomes 8th controlled by the PWM so that its movement closely approximates the ideal, intended movement.

Control of the actuator is further provided by the circuits 204 . 206 . 208 which monitors the actual voltage waveform of the line to be interrupted. For example, for a particular application, it may be determined that the contacts 71 . 72 within 1 ms of zero crossing A ( 6 ) of the voltage signal v (t) should open or close. The ideal motion profile, preprogrammed into the motion control circuit 226 in, includes the entire reaction and running time of the actuator 8th from the time an initiation signal is sent until the time when the contacts 71 . 72 shut down. If the ideal motion profile indicates that the response and delay for the contacts to close after the initiation signal is 7 ms, the microprocessor analyzes the actual voltage waveform of the line to be interrupted and determines a specific time between zero points. at which the initiation signal should be sent. The circuits 204 . 206 . 208 First, set the actual cycle period and the resulting length of time between zero crossings. The control circuit 200 then initiates the operation of the voice coil actuator 8th at a time after a zero crossing, which is equal to the actual time between zero crossings minus the reaction and running time of the actuator 8th is. Accordingly, if the actual voltage waveform indicates there is 8.3ms between zero crossings and the response and propagation time is 7ms, the opening sequence is initiated at 1.3ms after a zero crossing. In an alternative embodiment, the system may assume that the actual time between zero crossings is 8.33 ms, and the initiation is calculated based on this assumption.

In some embodiments of the present invention, a plurality of motion profiles may be included in the circuit 200 be pre-programmed into it and the appropriate motion profile can be selected by input from an operator.

Once the sequence is initiated, the actual movement of the actuator becomes 8th through the encoder 14 monitored and compared to the ideal movement profile. The current applied to the actuator 8th , is through the PWM 228 , based on the comparison of tat neuter movement of the actuator 8th with the ideal movement profile.

9 illustrates another embodiment of a voice coil actuator 308 which may be used in conjunction with any of the embodiments of the present invention. The voice coil actuator 308 includes an annular magnet 310 , which is preferably a 4 MGO ceramic magnet. The magnet 310 is in a soil pole part 312 and a top pole piece 314 shrouded. These pole pieces are formed of ferromagnetic materials such as iron or steel. The pole pieces 312 . 314 include a central opening 310 through which an actuating rod 318 extends. The operating rod 318 is in the pole parts 312 . 314 with self-lubricating polymer bearings 320 , such as IGUS ^TM bearings 320 , held.

An aluminum plate 328 is at the stake 318 fixed. At a peripheral edge of the plate 328 extends a coil 330 from the plate 328 in an air well 332 formed between the bottom pole part 312 and the magnet 316 , The sink 330 can be formed from a flattened wire so as to maximize the number of turns that are within the air well 332 to fit into it.

The actuator 308 can be powered by a 24 volt battery or by any other suitable power source, including a self-adjusting AC-DC converter.

To lock the device in a certain position, the actuating rod 318 a groove 320 include within the one ball 322 is arranged. Please refer 10 , A feather 324 and a cap 326 push the ball 322 in the groove 320 in to the pole 318 to restrain in a fixed position. The pole 318 can from the ball 322 be released under the application of a force, the level of which depends on the strength of the spring 324 depends.

To make a good connection between the contacts 71 . 72 can ensure the power of a spring 340 , or another force, on the pole 6 (or 318) can be applied to the contact 71 against the contact 72 with a predetermined force, such as 60-100 pounds. The spring can be compressed by the action of the actuator. Like now 11 shows, the actuating rod 6 . 318 a flange 342 which forms a surface against which the spring 340 suppressed. Another stop surface 344 may be provided to the opposite end of the spring 340 to keep.

The feather 340 provides the added benefit of maintaining adequate force between the two contacts 71 . 72 , For example, after repeated operations, arcing may be caused to wear the contacts. Due to the spring force, the two contacts are pressed against each other, just as they continue to wear. In addition, the application of force causes a reduction in the electrical resistance between the contacts in the closed position, thereby reducing heat losses.

If the contacts wear, the operating rod will become 6 . 318 Move a greater distance to compensate for wear. Because the position sensor 14 the distance to which the actuating rod 6 . 318 moved, feels, the system can be programmed to the maintenance signal 216 to illuminate, or any other indicator, to indicate that excessive wear on the contacts 71 . 72 occured. The system may also modify its motion profile to allow for increasing increases in the stroke.

Even though only preferred embodiments specific shown and described here will become apparent that many modifications and variations of the present invention in view of the above teachings and within the appended claims, without To leave the scope of the invention are possible.

Claims (8)

Circuit breaker ( 4 ), comprising: a current interruption device having at least one movable contact ( 6 ) and an actuator ( 8th ) connected to the movable contact of the circuit breaker; a feedback sensor ( 14 ) that monitors a position of the actuator during an actuation cycle; a sensor that detects a waveform of a voltage in a line to be switched and provides information regarding the voltage waveform; and a control system ( 12 ), which is connected to the feedback sensor, receives information from the feedback sensor with respect to the position of the actuator during the actuation cycle and is connected to the sensor for receiving information from the sensor with respect to the voltage waveform; characterized in that the voltage control system detects the movement of the actuator during the actuation cycle based on the information from the feedback sensor and the information NEN of the sensor controls to lock or release current in the line to be switched at a desired position on the voltage waveform; and wherein the actuating element is a voice coil actuator ( 8th ). Circuit breaker ( 4 ) according to claim 1, further comprising: means ( 200 ), which has a desired movement profile of the actuating element ( 8th ) stores; and a facility ( 200 ), which compares the movement of the actuating element with the desired movement profile and controls a movement of the Betätigungselemen TES also on the basis of a comparison of the movement of the actuating element with the desired movement profile. Circuit breaker ( 4 ) according to claim 1, wherein the feedback sensor ( 14 ) is a linear potentiometer. Circuit breaker ( 4 ) according to claim 1, wherein the current interruption device is a vacuum interrupter. Circuit breaker ( 4 ) according to claim 1, further comprising a spring, which biases the current interruption device in a closed position. Circuit breaker ( 4 ) according to claim 1, further comprising a catch ( 16 ), which limits the movement of the actuating element. Circuit breaker ( 4 ) according to claim 1, wherein the actuating element ( 8th ) a voice coil actuator ( 8th ); the feedback sensor ( 14 ) a linear potentiometer ( 14 ); the power interrupt device is a vacuum breaker; and further a spring ( 340 ), which biases the current interruption device to a closed position, and a detent ( 16 ), which limits the movement of the actuating element. A circuit breaker according to claim 1, further comprising includes: a sensor that is a waveform of a current in one to be switched line and information regarding the Provides current waveform to the control system; the Control system, the movement of the actuator further based on the information regarding the current waveform controls.