For a device, the control of movement, monitoring of state, and control of other switching values all require an electrical control system. It can be said that the electrical control system is the brain of the device, and the foundation of this system is the planning of the electrical control system.

The basic principles for planning the electrical control system are:

1. Satisfy the requirements of production machinery and production process on electrical control system to the maximum extent. The basis of electrical control system planning mainly comes from the requirements of production machinery and production process;

2. The planning scheme should be reasonable. On the premise of satisfying the control requirements, the planning scheme shall be simple, economical, easy to operate and repair, and do not blindly seek high indicators and automation;

3. Mechanical planning and electrical planning should be coordinated. Many production machines use the method of mechanical and electrical control to complete the control requirements, so it is necessary to deal with the relationship between machinery and electricity harmoniously from the aspects of process requirements, production costs, structural clutter, convenient use and protection, etc;

4. Ensure the safe and reliable operation of the control system.

The content of the principle planning includes: drafting the electrical planning mission statement, determining the electrical control scheme, planning the electrical control schematic diagram, accounting the primary skill parameters, selecting electrical components, preparing the component list, and preparing the planning statement.

The process planning is mainly to facilitate the arrangement of the production of the electrical control system, and then complete the various skill indicators proposed in the principle planning, and provide relevant drawings and materials for the commissioning, repair and application of equipment. The main contents of the process planning include: planning the general electrical arrangement drawing, general equipment drawing and general wiring diagram, planning the component arrangement drawing, equipment drawing and wiring diagram, planning the electrical cabinet, operating console and non-standard components, listing the component list Prepare the application protection statement.

The basic mission of electrical control planning is to plan and prepare all necessary drawings and materials during equipment manufacturing, operation and repair according to the control requirements.

The overall equipment planning mission of the electrical control cabinet is to first divide the control system into several components according to the working principle and control requirements of the electrical schematic diagram, then divide each component into several components according to the disorder of the electrical control cabinet, and then sort out the incoming and outgoing line numbers of each part according to the wiring connection of the electrical schematic diagram, and adjust the connection method between them.

The overall equipment planning is expressed by the general equipment diagram and general wiring diagram of the electrical system. The diagram should reflect the orientation of the main components of each part, the wiring connection of each part, the wiring method and the applied trunking, pipelines, etc. in a suggestive way.

The general equipment diagram and wiring diagram of the electrical control cabinet are the basis for divisional planning and harmonious composition of all parts into a complete system.

The overall planning shall make the entire electrical control system centralized and compact, and put heating elements and electrical components with large noise and vibration as far away from other components or isolate them as possible under space permitting conditions. For large equipment with multiple working positions, the convenience of operation in two places should also be considered: the main power switch of the control cabinet and the emergency stop control switch should be placed in a convenient and obvious position.

Whether the overall equipment planning is reasonable or not is related to the production and equipment quality of the electrical control system, and will also affect the completion of the performance of the electrical control system, the reliability of its work, the convenience and quality of its operation, commissioning and protection.

1. Differentiation of electrical control cabinet components

Due to different orientations of various electrical components and equipment, it is necessary to distinguish components when forming a complete electrical control system. The criteria for distinguishing components are:

(1) Assemble components with similar functions;

(2) Reduce the number of connections between components as much as possible, and place the control appliances with close connections in the same component;

(3) Let the strong and weak current controllers separate to reduce disturbance;

(4) In order to be neat and beautiful, we can combine the electrical appliances near the dimension and component;

(5) In order to facilitate the inspection and commissioning of the electrical control system, the components that need frequent adjustment, protection and vulnerable components are combined.

2. The wiring method between components, between electrical cabinets, and between electrical cabinets and controlled equipment shall be handled when distinguishing electrical control cabinet components.

The wiring method between parts and components of the electrical control cabinet shall generally comply with the following guidelines:

(1) The incoming and outgoing lines of switching appliances and control panels are generally connected by terminals or lugs, which can be selected according to the current size and the number of incoming and outgoing lines;

(2) Terminal blocks or industrial connectors shall be used for connection between electrical cabinets, control cabinets, cabinets (desks) and the controlled equipment;

(3) Weak current control components and printed circuit board components shall be connected by various types of standard connectors;

(4) The connection between the components in the electrical cabinet, control cabinet and cabinet (console) can be directly connected by using the terminal blocks of the components themselves. The terminal block shall be used for the transition connection, and the terminals shall be treated with the corresponding standard terminal blocks.

2、 Planning of electrical component placement drawing

Electrical component placement diagram is a combination of certain electrical components according to certain criteria. The layout of electrical components is based on the schematic diagram of components and the division of components.

The following guidelines should be followed in planning:

(1) In the placement of electrical components in the same component, attention should be paid to placing the large and heavy electrical components under the electrical panel, while the heating element should be located at the upper or rear of the electrical control cabinet, but the thermal relay should be placed at the lower part. Since the outlet end of the thermal relay is directly connected with the electric machine for easy outgoing, and its inlet end is directly connected with the contactor, it is convenient for wiring, shortest routing and heat dissipation;

(2) Strong current and weak current shall be separated and shielded to avoid external disturbance;

(3) The orientation of electrical components and equipment requiring frequent protection, maintenance and adjustment should not be too high or too low, and the orientation of manually operated switches and equipment requiring frequent monitoring should conform to ergonomic principles;

(4) Safety clearance shall be considered for the placement of electrical components, which shall be neat, beautiful and symmetrical. Electrical appliances with similar dimensions and structures can be placed together to facilitate processing, equipment and wiring. If the trunking wiring method is selected, the distance of each row of electrical appliances shall be appropriately increased to facilitate wiring and protection;

(5) After the orientation of each electrical element is determined, the electrical installation drawing can be made. The electrical installation drawing is made according to the outline of electrical components, that is, the distance scale of each component is marked based on its axis. The equipment dimension and tolerance scale of each electrical element shall be marked according to the specifications in the product specification to ensure the processing quality of the equipment board and the smooth equipment of each electrical appliance. The electrical components in large electrical cabinets should be located between two equipment beams, which can reduce the components of the cabinet, save materials, and facilitate equipment. Therefore, the vertical equipment dimensions should be calculated when planning;

(6) In the planning of electrical installation drawing, according to the number of incoming and outgoing lines of this component, select the wire specification and outgoing line orientation, select the incoming and outgoing line method, terminal block, connector or connector, and mark the wiring number of incoming and outgoing lines in a certain order.

3、 Planning of wiring diagram of electrical components

The wiring diagram of electrical components is made according to the electrical principle of components and the arrangement diagram of electrical components. It shows the connection of the complete set of equipment and is the basis for electrical equipment, repair and wiring inspection.

The wiring diagram shall be made according to the following guidelines:

(1) The preparation of wiring diagram and phase wiring table shall conform to the provisions of GB6988.6-1993 "Preparation of Control System Function Chart";

(2) All electrical components and their leads shall be marked with text symbols and wire numbers consistent with those in the electrical schematic diagram. The item code, terminal number and wire number in the schematic diagram shall be prepared in accordance with GB5094-1985 Item Code in Electrical Skills, GB4026-1992 General Rules for Identification and Use of Alphanumeric System of Electrical Equipment Terminal Blocks and Specific Wire Ends, GB4884-1985 Insulated Wire Symbols, etc;

(3) Different from the electrical schematic diagram, it is necessary to draw all parts (contacts, coils, etc.) of the same electrical element together in the wiring diagram;

(4) All electrical wiring diagrams shall be made of thin wires. Wiring methods are divided into two types: front wiring and back wiring. Generally, front wiring is selected. For simple electrical control components, if the number of electrical components is small and the wiring connection is not messy, the wiring between components can be directly drawn. For disordered components, if the number of electrical components is large and the wiring is messy, the wiring slot is generally selected. As long as the wiring number is marked on each electrical component, it is not necessary to draw the wiring between components;

(5) The wiring diagram shall indicate the type, specification, sectional area and color requirements of various wires used for wiring;

(6) When the components are connected with the external circuit, the incoming and outgoing lines of large cross-section wires should be connected with connectors, and others should be connected with terminal blocks.

4、 Planning of electrical control cabinet and non-standard part drawings

As far as hardware is concerned, electrical control cabinet includes: cabinet body, equipment board, laminate, heat dissipation equipment, operation panel, mobile equipment of cabinet body, rings, front door, rear door, left door, right door, etc.

The electrical control cabinets are divided into high-voltage cabinets, low-voltage cabinets, and some are strong current and weak current mixed cabinets.

From the perspective of structural method, the following are the most important:

1. General power cabinet+operation console. The power cabinet and the operation console are separated. The strong current part (circuit breaker, transformer, frequency converter, contactor, etc. are placed in the power cabinet) and the operation console are used to control the actions of the equipment and monitor the status of the equipment. They are generally used for large and high-power equipment.

2. Piano console (also known as bevel console). It is generally used for small equipment.

3. Computer console.

4. PLC cabinet. Equipment with many weak current control links.

The following aspects shall be considered in the planning of electrical cabinet:

(1) The overall dimensions and structural types of electrical cabinets and cabinets shall be determined according to the operation requirements and the dimensions of control panels, boxes and various electrical components in the cabinets. Under no special circumstances, the overall dimensions of electrical control cabinets shall be consistent with the fundamental dimensions and series of structures;

(2) According to the overall dimension, structural type and equipment dimension of the electrical control cabinet, plan the equipment support in the box, mark the equipment hole, equipment bolt and grounding bolt dimension, and indicate the matching method together. The materials of cabinets and boxes shall generally be special profiles for cabinets and boxes;

(3) Plan the method and type of opening the door of the electrical control cabinet according to the requirements of site equipment orientation, operation and repair convenience;

(4) In order to facilitate the ventilation and heat dissipation of the electrical appliances in the control cabinet, the ventilation hole or ventilation slot shall be planned at the appropriate part of the cabinet, and if necessary, the forced ventilation equipment and ventilation hole shall be planned at the upper part of the cabinet;

(5) In order to facilitate the transportation of the electrical control cabinet, a suitable lifting hook should be planned or a movable wheel should be planned at the bottom of the box.

In conclusion, according to the above requirements, the outline sketch of the electrical control cabinet box should be drawn first, the dimensions of each part should be estimated, and then the outline drawing should be drawn according to the share, and then the share of each dimension should be further adjusted from the aspects of symmetry, beauty, and ease of use. After the appearance of the electrical control cabinet is determined, the structural planning of each part of the control cabinet shall be carried out according to the above requirements, the general assembly drawing of the cabinet and the drawings of each door, control panel, base plate, equipment support, decoration strip and other parts shall be made, and the processing requirements shall be noted, and then the appropriate door lock shall be selected for the electrical control cabinet as required.

Of course, the shape and structure of electrical cabinets are different, and attention should be paid to the advantages of various types in cabinet planning. For non-standard electrical equipment parts, the part drawings shall be prepared according to the planning requirements of mechanical parts. The tolerance requirements shall be indicated for all matching dimensions, and the processing requirements shall be clarified.

Finally, it is also necessary to summarize and summarize various parts and materials required by the electrical control cabinet according to various drawings, and list the summary list of purchased parts, the list of standardized parts, the consumption quota of primary materials and the quota of auxiliary materials by category, so that the purchasing personnel and production management department can prepare materials according to the equipment production requirements, make production preparations, and facilitate cost accounting.