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First, secondary circuit diagram classification
The secondary circuit diagram is divided into schematic diagram, expansion diagram and installation diagram according to different drawing methods. This is also the three forms of engineering drawings commonly used in power production in China.
1, schematic
The schematic diagram of the secondary circuit is a drawing that reflects the working principle of the secondary circuit, and is the basis for drawing the development diagram and the installation diagram. All primary and secondary equipment are represented in the form as a whole, for example, interconnected current loops, voltage loops, DC loops, etc., are integrated. The advantage of this wiring diagram is that it allows the viewer to have an overall concept of the composition and operation of the entire secondary circuit.
Some of the shortcomings of the schematic are:
(1) Only the main components of the relay protection device can be indicated. The details are not shown.
(2) The actual position of the connecting line between the relays cannot be reflected, which is not convenient for maintenance and debugging.
(3) The internal wiring of each component, such as the terminal number, cannot be reflected.
(4) The marked "positive" and "negative" poles are relatively scattered.
(5) It is difficult to express complex relay protection devices.
The schematic diagram is mainly used to reflect the general working principle of the relay protection and automatic device and the composition of the device. It is impossible to explain the specific connection between the components, and the specific terminal and circuit number are not indicated. Therefore, the schematic cannot be used. On-site construction, extensive development of the map in the field work.
2, expand the map
The expanded view is drawn based on the schematic wiring diagram. The unfolding diagram is to draw the secondary equipment according to the wiring circuit of its coil and contact, and form a plurality of independent loops. It is an important technical drawing for installation, debugging and overhaul, and also the main basis for drawing the installation wiring diagram.
The features of the expanded map are as follows:
(1) According to different power circuits, it is divided into multiple independent circuits, mainly including AC current circuit, AC voltage circuit and DC circuit. DC loops can be divided into control loops, protection loops, measurement loops and signal loops according to their functions. In these circuits, the order of action of each relay is from top to bottom and from left to right.
(2) It is convenient to see the sequence of actions and clearly understand the connection order of similar circuits. It is a discrete representation of the components of the relay. For example, a relay whose coil is in the associated secondary current loop has its contacts in the associated DC loop. The symbols of the coils and contacts of the same component are the same.
(3) The role of the relay and each small logic loop is indicated on the right side of the expanded view.
(4) Each wire and terminal has a uniform specified circuit number and label for easy classification, construction and maintenance.
(5) The state of the contact drawn on the drawing is a state in which the power is not applied or is not operating.
(6) For the individual relays in the unfolding diagram, or the contacts of the relay are shown in another figure, the other installation units of the fire indicate that the directions are indicated on the drawings, and the descriptions are also given for any introduced contacts or circuits.
(7) The DC positive circuit is numbered in odd order, and the negative circuit is numbered in even order. After the loop passes through components (such as coils, resistors, capacitors, etc.), the label also changes.
(8) Commonly used circuits can be fixed numbers, such as 33, 133, 233, 333 for trip circuits, 3, 103 for closing circuits.
(9) In addition to the three-digit number, the label of the AC circuit is preceded by a text symbol. The range of numbers used in the AC circuit is: the voltage loop is 600~799; the current loop is 400~599. Their ones digits represent different loops; the ten digits represent the number of winding sets of the transformer. The label group used by the loop corresponds to the "number number" before the text symbol is dried. For example, the A phase circuit label of the 1TA current transformer should be A411~A419; the A phase circuit label of the voltage transformer 2TV is A621~A629.
Any circuit number associated with the screen on the expansion map should occupy a position on the terminal block diagram. In the expanded view, the wiring relationship of the secondary equipment is clear, and the sequence of actions is clearly defined, which is convenient for reading and analyzing. However, on-site installation requires a more specific installation wiring diagram.
3, the installation diagram
The installation drawing is the drawing used for the production screen and the on-site installation of the control panel and the protective screen manufacturer. It is also the main reference drawing for the operation test, maintenance, etc., and is drawn according to the development drawing. The installation diagram includes the screen layout, the rear panel wiring diagram, and the terminal diagram.
(1) Screen layout
The screen layout diagram refers to the actual installation layout of each device in the screen as seen from the front of the screen. The installation position and external dimensions of each device on the screen are drawn proportionally, and a list of equipment should be attached to list the name, model, technical data and quantity of each device in the screen for material preparation and installation.
(2) screen rear wiring diagram
The wiring diagram on the back of the screen is based on the layout of the screen and is drawn based on the expanded view. The rear panel wiring diagram is the device graphic seen from the back of the screen. It is drawn according to the actual position and basic size. Its position is opposite to the left and right of the screen layout. The figure shows the connection between the terminal strips of each device on the screen. It can be used by the manufacturer to guide the wiring of the screen wiring, or it can be used by the construction unit for the installation of the secondary equipment on site.
For the convenience of wiring, in this wiring diagram, the relative numbering method is generally used for each device and the terminal block to indicate the interconnection between the devices. The so-called "relative numbering method" is, if the two terminals of A and B should be connected by wires, then the number of the terminal of the terminal is next to the terminal of the terminal A, and the number of the terminal of the terminal is next to the terminal of the terminal. In this way, when wiring and repairing, you can find the connected object for any terminal of each device on the screen according to the drawing. If there is no number next to a terminal, it means that the terminal is empty; if a terminal is marked with two labels, it means that the terminal has two connections and there are two connection objects.
(3) Terminal block diagram
The terminal block diagram is a diagram of the various types of terminal arrangements required to connect the devices in the screen and the connections to the devices inside and outside the screen.
Whether the secondary wiring is connected through the terminal block, the design of the terminal block should be carried out according to the principle of convenient inspection, operation, and convenient adjustment of the junction box;
The setting of the 1 terminal block should correspond to the equipment in the screen. For example, the device near the left side is connected to the left terminal block, and the right device is connected to the right terminal block. The devices above and below should also correspond to the terminal block, so as to save wires. Easy to check and repair.
2 The connection between each installation unit, the connection between the on-screen device and the off-screen device, and the circuit that needs to be transferred via this screen should pass through the terminal block.
3 The connection between adjacent devices on the same screen does not pass through the terminal block; when the two devices are far apart or the wiring is inconvenient, they should pass through the terminal block.
4 The positive power supply should be connected through the terminal block. The negative power supply should form a loop between the devices in the screen. The two ends of the ring should be connected to the terminal block.
The connection between the 5 screen devices and the devices directly connected to the small wires (such as fuses, small isolation switches or additional resistors) should generally pass through the terminal block.
Terminals should be installed on the upper and lower ends of the 6-terminal row, and 2~5 terminals should be reserved at the end of each installation unit terminal block as spare.
7 One side of the terminal is generally only connected to one wire, and no more than two.
For convenient wiring, the terminal strips are arranged in order from top to bottom according to the nature of the loop, and the sequence is as follows:
(1) AC current loop. According to the Meizu current transformer group, and in the A, B, C, N phase sequence, the numbers are arranged from small to large.
(2) AC voltage loop. Grouped by Meizu voltage transformers, and arranged by A, B, C, N, L.
(3) Signal loop. Grouped by notice, accident, location and command signal.
(4) Control loop. According to each group of fuses grouped, each group is first arranged in the positive circuit (single number, from small to large), and then the negative circuit (double number, from small to large).
(5) Other circuits and transfer circuits
The wiring and numbering in the terminal block diagram are also based on the principle of relative numbering.
Second, the secondary circuit diagram identification method
The biggest characteristic of the secondary circuit diagram is that it is very logical. The operation of its equipment and components is strictly in accordance with the order of design. Therefore, as long as you grasp certain regulations when looking at the drawings, it will be easy to understand the drawings and make it clear. .
1, the basic skills of the second drawing
Before looking at the picture, first understand the name of the device represented by the symbol on the drawing, and also understand the action logic of the individual components and relays. To understand a drawing easily and easily, you must master the drawing skills. The overall principle is: first time, second time; first exchange, then DC; first power supply, rear wiring; first coil, rear contact; first After the next; first left and then right.
(1) "First time, second time later". That is, when there is a secondary wiring of the junction box at the same time, you should look at the part first to find out what equipment and work nature, and then look at the secondary part of the monitoring effect, and what monitoring effect.
(2) "First exchange, then DC". That is, when there are two circuits of AC and DC in the figure, you should look at the AC circuit first, then the DC circuit. The AC circuit is generally led out by the secondary winding of the current transformer and the voltage transformer, which directly reflects the operation status of the primary equipment wiring. After understanding the AC circuit, the amount of electrical energy according to the AC circuit and the amount of electricity in the event of a system failure The characteristics of the change, the logical inference of the DC loop, it is easier to see the DC loop.
(3) "First power supply, rear wiring". That is, whether in the AC circuit or the DC circuit, the action of the secondary device is driven by the power supply. Therefore, when looking at the picture, the power should be found first, and then the cable connection continues to look backwards, and the AC follows the closed loop. Analyze the action of the device, DC finds the negative power from the positive power supply along the wiring, and analyzes the actions of each device.
(4) "First coil, rear contact". In order to analyze the action of the contact, the coil of the relay or device must be found first, because only the coil is energized, its corresponding contact will act, and the change of the loop caused by the on and off of the contact further analyzes the action process of the entire circuit. In one picture, the coil and its contacts are closely connected. When the coil is looking for a contact and the contact is looking for a coil, this is a great technique for quickly looking at the picture.
(5) "First up and down" and "Left left and right". The secondary wiring drawings are drawn from top to bottom and left to right according to the logical sequence of the bad devices or loops. The terminal block diagram and the rear panel wiring diagram are also arranged in this way. Therefore, when looking at the picture, first look up, down, and left to right, it is in line with the logic of protection action, and it is easier to understand the drawing.
The terminal block diagram should be combined with several open views. Simply look at the terminal block diagram, just a series of numbers and lines. Nothing can be seen. Only when combined, can we connect into a complete loop and understand the circuit drawings.
2, the common method of viewing pictures on site
In the field work, the common method oil to understand the working principle of the secondary circuit:
(1) The DC link is from the positive pole to the negative pole. Such as control loops, signal loops, etc. Starting from the DC positive pole of a loop, the negative pole is seen in the direction of current flow.
(2) The AC loop is from the phase line to the neutral line. Such as current, voltage loops, air-cooled circuits of transformers. Starting from the phase line (A, B, and C phases) of one circuit, the neutral line (N level) is seen in accordance with the flow direction of the current.
(3) See the contact to find the coil, see the coil to find the contact. When you see the contact, you need to find the coil position of the relay or contactor that controls the contact. The loop in which the coil is located is the control loop of the contact to analyze the conditions under which the contact operates. See the coil to find all its contacts in order to find all the contacts (objects) controlled by the relay. This is also what I said before.
(4) Use Ohm's law to analyze whether the relay is operating. The basis for the discrimination is that the voltage type coil is provided with a sufficiently large voltage at both ends, and the current type coil is provided with a sufficiently large current at both ends.
(5) After reading all the branches. When a loop looks from the positive pole to the negative pole, if there are multiple branches connected to the negative pole in the middle, each branch must be read, otherwise the analysis loop will miss some important situations.
(6) Use the relative numbering method and the circuit label to clarify the correspondence between the equipment in the wiring diagram of the installation diagram and the expansion diagram. The main purpose is: first, check whether the installation diagram corresponds to the expansion diagram; second, find out the location of each device in the deployment diagram on the site. From the installation diagram (such as the protection screen terminal block wiring diagram) to find out the position of the terminal of a terminal block in the unfolded picture, first find the circuit label where the terminal is located, and then find the loop number in the expansion diagram, the same circuit table The box is the same loop, and the loop can be quickly found in the unfolded view, and the expanded graph is used to find out its role in the entire loop. If there is only a installation diagram on the hand or if the schematic diagram of the installation diagram and the expansion diagram cannot be matched, the number of the other equipment connected to the terminal of each equipment terminal in the installation diagram is checked according to the relative numbering method. Then, find out the other equipment connected to the terminal until the phase and neutral lines of the positive, negative or AC loop of the DC power supply are found. Finally, the entire relevant loop is detected. After drawing the graph, it can analyze whether the connection conforms to the action principle. When the phase of the device on the unfolding map is located, the first is to use the equipment table on the unfolded map to provide the location, and then to find the corresponding installation map; second, first find out the terminal symbols in the expanded map, which are the cabinets Terminals of the terminal block, which are the terminals of the (protective or automatic) device, and then go directly to the possible panel and terminal box for searching.
(7) Solution to the problem of special problems
1 Describe the operating conditions of the circuit or relay using the actual state of the equipment (the status of the equipment that can be seen in the field). Firstly, the condition of the loop is described by the contact state of the loop, and then the corresponding relationship between the state of the contact and the state of the contact and the state of the device is replaced, and the description is as follows: the remote control of the switch box "far/near control switch" is used. The state of the contacts in the loop must gradually form this capability. Otherwise, the drawing will remain in the original state. Only the contact, the combination and the relay are excited. It cannot be combined with the monitoring and operation of the equipment in operation.
2 Find out the connection between the device in the expanded picture and the other parts of the frame. Line check the terminal number of the box drawing equipment, and then use the device manual or manufacturer's drawing that can display the internal wiring diagram of the equipment, find the terminal number of the external connection in these drawings, connect it to the internal circuit, and then go out. The connected terminals are then connected to the external circuit.
3, the second look at the notes
(1) Although the most important drawings in a set of secondary drawings are control and signal loop diagrams, current and voltage loop diagrams, protection screen terminal diagrams, and installation wiring diagrams of circuit breakers, you should be familiar with these drawings when looking at the diagrams. But you can't ignore the auxiliary functions of other drawings, otherwise you may get twice the result, and you can't come out or miss some special loops.
(2) It is easy to use some common circuit numbers and graphic symbols. When you look at the pictures, you will greatly accelerate the speed of reading the drawings.
(3) Pay special attention to the equipment operated by the attendant, such as power insurance, air-opening, switch, their position in the drawing and their role, you must find out the actual location of their site.
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In the secondary circuit diagram, the corresponding secondary equipment is represented by the unified graphic symbol text symbols specified by the state, and these graphic symbols are connected to each other to form a control loop, a relay protection loop, a measurement loop, a signal loop, and an automatic device loop. , as well as AC voltage and AC current loop diagrams.