The disconnector is a switching device for voltages above 1 kV, the main purpose of which is to create a visible break and isolate parts of the system, electrical installations, individual devices from adjacent live parts for safe repair.
In addition to this main purpose, disconnectors are also used for other purposes, since their design allows this, namely:
- for turning off and on unloaded power transformers of small power and lines of limited length under strictly established conditions;
- for switching switchgear connections from one busbar system to another without interruption of current;
- for grounding disconnected and isolated sections of the system using auxiliary knives provided for this purpose.
Disconnectors have a relatively simple design. It is mandatory to have a visible break in the air in the "off" position, creating confidence that the area in question is really disconnected and isolated from adjacent parts. Disconnectors are equipped with drives - manual or electric motor - for non-automatic control. The cost of the disconnector is much lower than the cost of the circuit breaker, the requirements for maintenance and repair are also lower.
Fig.1. Diagrams explaining the use of disconnectors:
a - when isolating the circuit breaker for repair;
b - when switching connections
Let us explain the operating conditions of disconnectors using the following examples. To prepare the circuit breaker for repair, it must be disconnected and isolated from adjacent live parts using two disconnectors QS1 and QS2 (Fig. 1, a). In this case, the disconnectors disconnect the capacitive current, the value of which is determined by the mains voltage and the capacitance of the switch inputs. This current is small, and arc discharges do not occur on the contacts of the disconnectors. After disconnecting the disconnectors, the circuit breaker Q to be repaired must be earthed on both sides using additional blades QSG1 and QSG2.
Switching of RU connections under current with the help of disconnectors is carried out under the obligatory condition - the presence of parallel branches with low resistance. So. for example, if there are two parallel branches with disconnectors QS1 and QS2 (Fig. 1b), one of the disconnectors can be safely opened under current if the disconnector of the second branch is switched on. When the disconnector is turned off, the current is shifted from one branch to another. In this case, arcs are not formed on the contacts.
Three-pole disconnectors with common pole control have been predominantly used. The latter can be interconnected mechanically, electrically or pneumatically.
Disconnectors for indoor installation
These disconnectors are usually of the vertical-chopping type with blades rotating in a vertical plane perpendicular to the base.
Fig.2. Three-pole disconnector type RVR 10 kV, 2000 A
with two sets of earthing knives
A three-pole disconnector of the RVR type - internal installation, chopping (Fig. 2) - has two support insulators 1 per pole, mounted on a base 2 made of profile steel. The third - traction insulator 3 is used to drive the main knives 4. Disconnectors are equipped with additional knives 5 for grounding - one or two for each pole. Shaft 6 and the system of levers of each pole serve to control the main knives. The leading levers are mounted on the shaft and are pivotally connected to the traction insulators. The latter are connected with knives. The shaft is driven by a drive. In this case, the main knives are rotated by an angle of about 60 °. The grounding blades 5 of each side are mounted on special shafts 7 and interconnected by a copper bus 9. Special drives are required to control the grounding blades. The current-carrying parts of the disconnector (clips 8 for connecting busbars, contacts, blades) are made in accordance with the rated current of the disconnector. The larger the latter, the larger the cross section of the knives.
Fig.3. Contact system of RVR type disconnector 10 kV, 1000 A
For disconnectors with a rated current up to 1000 A inclusive (Fig. 3), the knives consist of two copper strips 1 of rectangular section, covering the contact rack 2. The side surfaces of the rack have a cylindrical shape and form linear contacts with the knife plates. The pressure in the contact is created by springs 3 mounted on the rod. The pressure on the knives is transmitted through steel plates 4 with ledges. With a short circuit and a sharp increase in current, the knife plates are attracted to each other, increasing the pressure in the contact. Steel plates increase the magnetic induction and create additional pressure in the contacts. This kind of magnetic locks supply most of the disconnectors.
For disconnectors with a rated current of more than 1000 A, the main knives consist of two and four parts of a box section (Fig. 2). The contact surfaces are coated with a silver layer 20 µm thick. Magnetic locks are also provided.
To control the main and grounding knives, drives are provided, the device of which depends on the rated current of the disconnector. A manual drive is a system of levers or gears with which a person can turn the disconnector shaft. The greater the rated current of the disconnector, the greater the friction force in the contacts. The drive mechanism must be calculated accordingly.
Disconnectors with a rated current of 4000 A and above are equipped with worm gear drives operated manually or by an electric motor. For grounding knives there are separate drives, usually lever. The latter are blocked with the drives of the main knives in order to exclude the possibility of turning on the grounding knives when the main knives are turned on, as well as the possibility of turning on the main knives when the grounding knives are turned on.
Fig.4. Installation of a three-pole disconnector type PVR with earthing blades
Figure 4 shows the installation of a 10 kV 2000 A three-pole disconnector with two sets of earthing knives. The drive of the main knives 1 is electric, and the drives of the grounding knives 2 are worm. All actuators have auxiliary contacts 3 for position signaling and blocking.
Disconnectors for outdoor installation
In the days of the USSR, the most widespread disconnectors were of the horizontal rotary type with knives rotating in a horizontal plane parallel to the base. They are manufactured for voltages from 35 to 500 kV inclusive.
Fig.5. Three-pole disconnector for outdoor installation
type RND 110 kV, 2000 A
RND type disconnector - external, two-column (Fig. 5) - has two columns of insulators 1 per pole, installed vertically in bearings on a steel frame 2 and interconnected by a system of levers 3. When the insulators turn, the knives 4, mounted on the heads of the insulators, also rotate. Clamps 5 for connecting conductors to the disconnector are pivotally mounted on the heads of the insulators and connected to the knives with flexible tapes 6. When the insulators rotate, they do not rotate. The contacts of the disconnector 7 are located at the junction of the knives. They consist of a number of plates mounted on one knife, and a “blade” on the other knife. The pressure in the contacts is created by springs. The disconnector blades are adapted to work in winter with ice. They consist of two plates hinged (not shown in the figure).
In the process of disconnecting, the knife “breaks” and destroys the ice formed on the contacts. Disconnectors are equipped with 8 earthing knives - one or two per pole. In the off position, the blades are located horizontally at the base of the disconnector. When turned on, they rotate in a vertical plane by an angle of 90 °. In this case, the contact at the end of the grounding knife is connected to a special contact 9 on the main knife.
The poles of a three-pole disconnector are interconnected by a lever system 10 and are controlled by a common drive 11. The middle pole is the leading one, the extreme poles are the driven ones. The grounding blades have separate drives interlocked with the main blade drives.
Breaking capacity of disconnectors
The breaking capacity of a disconnector should be understood as its ability to break a current of the order of several amperes or several tens of amperes under certain conditions.
The process of disconnecting the circuit with a disconnector proceeds as follows. When the disconnector is opened, arcs are formed at the discontinuities. Under the influence of the magnetic field and the released heat, they rise and stretch in the form of loops (Fig. 6). Such arcs are usually called free or open.
Fig.6. Free arc on disconnector contacts
Due to weak deionization, the arc column retains its conductivity at the moments when the current passes through zero and the arc burns for tens of periods. As the arc lengthens, its resistance and breaking voltage increase, and the current decreases (Fig. 7).
Fig.7. Oscillograms of current and voltage on the contacts of the disconnector:
a - opening of a 33 kV ring line with a current of 133 A, arc duration 22 periods;
b - disconnection of an unloaded transformer with a current of 18 A, arc duration 25 periods
At a certain arc length, called critical, the mains voltage is insufficient to maintain it, the current drops to zero, and the voltage at the break is restored to the mains voltage. Due to the strong damping, the recovery voltage does not contain the high frequency components that are characteristic of circuit breakers equipped with quenching chambers.
Experiments have shown that a free alternating current arc in air is extinguished if there is sufficient space for it to reach a critical length and if the distance between the contacts of the disconnector is sufficient to prevent its re-ignition. Maximum arc extension, i.e. the greatest distance from the midpoint of the straight line connecting the disconnector contacts to the point of greatest arc removal depends on the mains voltage and the current to be switched off.
Fig.8. The dependence of the maximum arc extension
on the contacts of the disconnector from current and voltage
Figure 8 shows this dependence in relation to the disconnection of inductive and active currents.
Switching off by a disconnector even relatively small currents, especially capacitive ones, is associated with the danger of arc transfer to adjacent phases and to grounded parts, which is unacceptable. As the voltage and interrupted current increase, this danger increases. The rules for the technical operation of electrical installations (PTE) allow the operations of switching on and off electrical circuits with disconnectors under strictly defined conditions. So, for example, switching on and off by disconnectors of measuring voltage transformers is allowed. At voltages up to 10 kV, it is allowed to switch on and off the load current up to 15 A with outdoor disconnectors. Table 1 shows the breaking currents allowed by PTE for the most common disconnectors of the RND series.
Table 1
The highest magnetizing currents of transformers and charging currents of lines,
allowed to be disconnected in outdoor switchgear
horizontal type disconnectors
Disconnect Ratings
The rated parameters of the disconnectors are: rated voltage, rated current, rated dynamic withstand current and rated thermal withstand current. Manufacturers do not indicate the breaking capacity of disconnectors, since it depends on many conditions, in particular, on the distances between the poles and to grounded parts, which are chosen by design organizations.
Separators have the same parameters as disconnectors; the nominal operating time is additionally indicated.
The nominal parameters of the short-circuiters are the rated voltage and the rated switching current - the instantaneous value i on and the effective value of the periodic component I on. These values must be compared with the corresponding calculated values i beats and i p0 . In addition, the total turn-on time is indicated.
This work was attended by students of the program from JSC "PO "Electrochemical Plant": Head of the Central Laboratory Dmitry Arefiev, Lead Engineer of the Production and Technology Department Dmitry Rogozhin and Head of the ACS Group of the Automation Division of the Separation Production of the Metrological Service Yaroslav Bombov.
Module 4 of the Technological Innovation Management program was a foreign internship to study the European RnD model (RnD is an analogue of the Russian abbreviation R&D, research and development). During the week, from November 12 to 18, the students visited several modern production, research and development centers in the Netherlands, Belgium and Germany: the so-called "golden triangle" between the cities of Eindhoven, Leuven and Aachen, where the electronic industry and scientific potential of Western Europe.
The task of Russian nuclear scientists was to adopt international experience in organizing the process of introducing technological innovations. Including - the experience of handling the results of intellectual activity, the organization of financing for R&D and the degree of participation of the state in this, the organization of domestic and international partnerships.
As Yaroslav Bombov said, the group in which he works within the framework of the main program for managing technological innovations is developing the project “Model of an open international chemical RnD center”, therefore the topic of this foreign internship almost completely fell into the subject of the group and was very useful for further work . However, it was extremely interesting and informative for all participants, including, of course, for Dmitry Arefiev and Dmitry Rogozhin, who are developing with their group the project “Strategy for entering the markets of new technologies (products, goods, services)” (on the example of monazite) .
An illustrative example of the development of R&D technologies was seen by the participants when they visited one of the largest research centers in Europe in the city of Leuven in Belgium (IMEC). The center has a powerful production and research base, in addition to scientific and applied developments, it conducts training programs - for this, an academy of science and technology has been created under it.
The Center occupies a leading position in the field of pioneering projects, in particular, the preparation of technological platforms in microelectronics. In the tradition of the center - wide international cooperation. Thus, the three largest manufacturers of microelectronics in the world (Intel, Samsung, Toshiba), which have their own production facilities, closely cooperate with the center in terms of joint financing of the development of the latest technology platforms, which are then introduced into their own production. Currently, even such huge players in the microelectronics market cannot afford the costs of developing a technological platform alone. However, the entrepreneurial component of the activities of the R&D center is not limited to this and includes the development of unique electronic devices to order and equipment testing. The center also conducts research in the field of conjugation of electronics and living tissues.
The Center for Nuclear Research in the city of Mol is closer to our research institutes in terms of the specifics of its work, however, the processes of commercialization of scientific activity are also noticeable here: special divisions are being created that try to isolate those that can be quickly put into production among a large number of scientific developments. One of the activities of the center is research in the field of nuclear waste disposal technologies and the creation of the MYRRHA reactor (Multi-purpose hybrid research reactor for high-tech applications).
Perhaps the most striking example of cooperation between science and business is the business incubator in the city of Delft (Holland), created on the site of the local Technical University. The interaction of scientists and business makes it possible to raise the status of each individual project and creates an innovative environment that facilitates its implementation. The business incubator, in turn, is part of a training module for the training of entrepreneurs from among university students. By the way, as Yaroslav Bombov said, for small projects (requiring up to 15 thousand euros for implementation), business gives money without a guarantee of a mandatory return. That is, if the project does not go to court, no one will drag you to court, the main thing is to prove that you spent the money allocated specifically for the implementation of the project. Well, if it didn’t work out - what can we do ... Investors are going for it, since there are many such projects and some of them are sure to “shoot”, bringing a very decent profit. The state also participates in the process, financing, together with business, the creation of an infrastructure for growing its own intellectual elite, which, of course, only benefits the state.
The foreign internship ended with the formation of a single presentation of the participants based on the results of the trip: first, each group formulated its conclusions, then a joint discussion of the results took place and a common opinion was formed regarding the companies visited by Russian nuclear scientists.
Namely. In Europe, the relationship between R&D and business is traditionally close. Finance, patenting and other auxiliary functions are separated into a separate service (the researcher gets more time for the main task), there are business support groups. The focus of scientists and students on the commercialization of their developments is highest in the Netherlands, moderate in Belgium, and less than others in Germany. A high degree of state participation and support for the innovative activity of enterprises is noticeable; public funding for R&D and science is maximum in Germany. In general, in Europe, R&D activities are declared as socially significant.
As for the cultural program of the trip, it was cut to a minimum. Due to the extremely tight work schedule for the main program. Not without reason, remembers Yaroslav Bombov, the first desire upon returning to Skolkovo was to get a good night's sleep...
Well, the 5th module of the "Management of technological innovations" program, called "Project and personnel management in R&D" (including the subsection "The role of a leader in achieving a successful result") was held in the usual format: lectures, seminars and work on group projects that participants to be defended at the end of the course. By the way, one of the invited experts who spoke on the topic of the role of a leader was the famous mentor of Russian figure skaters Tatyana Tarasova ...
Grigory Rostovtsev
Today, high-voltage separators RLND are actively used in electrical systems. These devices were developed relatively recently, but have already been able to gain popularity among consumers. The main reasons for this are low cost, long service life and reliability in operation. As a result, linear separators are superior in their characteristics to more expensive analogues.
Abbreviation decoding
In electrical engineering, many devices have an abbreviation, and if you decipher it, you can understand their purpose, for example, OCO. In the case of disconnectors, the situation is even simpler and all letters here are shorthand for the full name. As a result, the decoding of the RLND has the following form:
- R - disconnector.
- L - linear.
- H - external
- D - two-column.
Similarly, RND or other separators, for example, RNDZ, are decoded. Both of these devices are linear two-column separators for outdoor installation. The difference between them lies in one letter "Z", indicating the presence of a grounding conductor. The situation is similar with RLNDZ.
Also, the designation of separator models contains information about the main technical characteristics. It is presented in the following form - A-B-C. V/G-D. Instead of letters, the corresponding values \u200b\u200bare indicated who can say the following:
An example is the model RLND-1−10/630 U1. This disconnector is designed for mains voltage up to 10 kV and is equipped with one earthing knife. The rated current of the device is 630 A. The situation is similar with the decoding of the RLND 10-400 disconnector model. From the product labeling, it can be understood that the rated current indicator is 400 A. Also, the abbreviation with the decoding of 10-kilovolt devices indicates the presence of products designed for a current of 200, 400 and 630 amperes.
Design and principle of operation
The design of the RLN devices is quite simple. and this is the key to their reliability. Each pole is equipped with a movable and fixed operational rod (columns), which ensure the rotation of the knife in a horizontal plane. The dimensions of the 110 series products are indicated on the drawing.
After this, the devices create a visible break in the electrical circuit. and carrying out repair or service work on a specific section of the power line can be read as safe. Separators are intended for installation on electric main supports, for example, SV-110−35. Installation of products is carried out during the construction of power lines or in places of new connection to them.
The manufacturer took care of the simplicity of not only the design, but also the adjustment of their product. This process, in fact, consists only in setting the knives, which will make it possible to achieve the synchronous operation of these elements.
To solve the problem, loosen the bolts, adjust and tighten the fasteners again. After these manipulations, the contact zone of each knife is checked, and its size must be at least 8 mm.
The replacement of the device should be carried out in cases where severe damage was found on it, for example, burnt out contacts. It should also be remembered that maintenance must be carried out in strict accordance with safety standards.
Often our attention on the road is caught by “beautiful” license plates. They are usually called thieves, because getting this can hardly be called a happy accident. Coinciding or mirror letters and numbers, as well as combinations endowed with special meaning. Everyone probably dealt with a kind of decoding of such “thieves” numbers, but in fact, many of them have a very specific background and can give a certain signal to traffic police officers and other road users. It is impossible to give an unambiguous decoding to all license plates, so the list contains the most common of them.
MOSCOW
EKH77 - numbers allocated for cars of the Federal Security Service (FSO) of the Russian Federation. A common version of the decoding of such a set of letters is the story once presented in the Autopilot magazine. According to her, wanting to add a new one to the AAA series already assigned to the FSO, the head of the service, Yuri Krapivin, turned to Boris Yeltsin, who was then president of the Russian Federation. Together they chose EKH as an abbreviation for Yeltsin+Krapivin=Good. The official decoding is considered to be "a single Kremlin economy." There is another option that has taken root among the people - "I eat as I want." Now this series can be seen infrequently.
EKH 99, EKH 97, EKH 177, SKA77 - Federal Security Service of the Russian Federation.
XKX77 - partly FSB autonomer, partly sold out.
SAS77 - not found now, once belonged to the FSB.
AOO77, BOO77, MOO77, COO77 - are typical for cars that are assigned to the Office of the President.
KOO77 - Constitutional Court, private traders.
AMP97 - the series was formed as a result of the struggle with a large number of special signals. These badge numbers were issued to vehicles that, regardless of ownership, retained the right to use blue lights (with the exception of the AAAFL). So, part of the series belongs to the FSB, part of the Ministry of Internal Affairs and part to other structures, for example, the presidential administration.
AKP177, WKR177, EKR177, KKR177 were also issued to those who fell under the abolition of the use of blue car flashers. Of the last two episodes, probably something went to private traders.
EP177 - about 300 numbers served as a replacement for the "flag" of the State Duma. Popular decoding - "United Russia is coming."
OOO77, 99, 97, 177, 199 - now mostly private traders and merchants.
CCC77 - the series distinguishes the cars of the Courier Service, the Special Communications Center, the Ministry of Communications and structures "close" to them, and can also be used on personal vehicles. The popularly known decoding of such thieves numbers is “three Seeds”.
CCC99 - predominantly private traders.
CCC97 - GVCs and private.
MMM77, 99 - now - private traders, before the appearance of blue car numbers - the Ministry of Internal Affairs.
AAA77, 99, 97, 177, 199 - now with a high probability of private traders.
XXX99 - private traders, FSB.
KKK99 - private traders.
ННН99 - may be with tax police, STC, private traders.
Other identical letters are just "beautiful" license plates. Decryption can be done by yourself.
AMM77 - a series for personal auto and service authorities of the traffic police in the capital, previously intended for vehicles of the Ministry of Internal Affairs of the Russian Federation.
*MM77 - used by the Moscow police before blue license plates appeared.
AMP77 - previously only cars of the Central Bureau of the Ministry of Internal Affairs of the Russian Federation, and now private cars of the leadership and ordinary citizens.
KMP77 - simple thieves numbers.
MMP77 - private traders, a little FSB.
PMP77 - the series corresponds to the cars of the Ministry of Justice.
TMP77 - vehicles of the Department for Ensuring Law Enforcement in closed territories and sensitive facilities, including cosmonauts and private traders, that are not available in the base.
AMO77 - Moscow administration, private traders. Initially, these license plates had one more feature: there was no tricolor, and the letters rus were voluminous.
AMO99, 97 - thieves private traders, including those directly related to the Moscow administration.
NAA99, TAA99, CAA99, XAA99 - "closed" in the databases of the series (POPIZ - upon written request).
EPE177 - deputies of the Federal Assembly, private traders (popular decoding - "United Russia Is Going").
SKO199 - Investigative Committee under the Prosecutor's Office of the Russian Federation.
The same letters and numbers 177 are thieves, extremely common near the building of the State traffic inspectorate on Sadovaya-Samotechnaya.
Any "round" numbers, especially the first tens with two zeros at the beginning (001-009) or at the end (100, 200, ..., 900), with three identical numbers (111, 222, ..., 999), the most prestigious thieves combinations - 77777 or 99999, which have all the same digits, including the region code.
NOVOSIBIRSK REGION
AAA54 - the first hundred numbers belong to the presidential envoy, then - thieves.
ННН54 - cars of the city hall of Novosibirsk, the administration of the Novosibirsk region and the regional council. Among the townspeople, a popular decoding is "Do not touch the Novosibirsk Administration." Interestingly, the armored cars of one of the commercial banks also use NNN numbers, but Kemerovo ones.
ASK54 - FSB in the Novosibirsk region, after the 200th - thieves.
ANO54 - old series for the administration of the Novosibirsk region (used before the introduction of "NNN").
РРР54 МОР54 - "Morozov" numbers, such a decoding is associated with their introduction by the former head of the UGIBDD, Peter Morozov.
NSO54 - thieves "Yakovlevskaya" series, got its name thanks to the former head of the UGIBDD Vitaly Yakovlev.
MPO54 - When the letter D was forbidden to be used in the license plate series, the old MVD54 was replaced. With the advent of the head of the UGIBDD, S.V. Shtelmakh was again replaced. The following decoding dominated among the people: "The cops Disappointed, It's a shame."
OOM54 - special series of the head of the UGIBDD S. V. Shtelmakh.
MVU54 - numbers of the Central Internal Affairs Directorate for the NSO.
VVV54 - a series of the head of the Central Internal Affairs Directorate for the Novosibirsk region.
UVU54 - used by the police department and traffic police.
UVO54 - Department of private security at the Central Internal Affairs Directorate for the NSO.
Other series of numbers with flashing lights
VMR - government, private individuals, banks.
EEE - private individuals who have blat in the traffic police. It doesn’t even need to be deciphered, judging by the letters, the owners are satisfied.
KKH - FSB, FSO, etc.
KMM - firefighters and thieves.
OMR - the government, banks, selected private traders.
SMM - police and part of the connection (SMM is usually deciphered as social media marketing, well, maybe one of them really works there).
SSS - FSO, FSB, government, private individuals who have blat in the traffic police.
UMR - the government and private traders by pull.
UUU - exclusively thieves.
Deciphering thieves' license plates will help you understand a little better what is happening on the road. Take advantage of the opportunity to re-register a car with the preservation of numbers, if you do not want to part with your license plate when changing cars.