Design of electrical power equipment of conveyor electric drive

Contents

Table of contents

Introduction

Development of schematic diagram of electric drive control

Electric motor selection

Selection of protective and switching equipment

Selecting Cable Lines

Electrical Layout and Electrical Routing

Development of Cable Log

Pipeline Line Single Line Design

Bibliographic list

Applications

1. Introduction

In recent years, conveyor transport has been increasingly used in metallurgical plants for transporting bulk loads of raw materials and fuel. This type of transport is used not only at newly built and designed enterprises, but also at existing ones - during the reconstruction of the main units. Conveyors are used to transport raw materials from car dispensers, sorting stations or from the wharf of the factory port to a warehouse, from a warehouse to an agglomeration factory, to blast furnace and coke-chemical workshops. Conveyor transport is also used to supply solid fuel to the CHP; limestone, ore and other materials - in steelmaking shops, etc.

Conveyor transport is widely used for domestic transport. This is greatly facilitated by an increase in the degree of continuity of technological processes of the first alterations of coke, agglomeration, blast furnace, steelmaking, in which other modes of transport do not provide the modern level of production of these alterations. Of the conveyors of all types, the most widespread in metallurgical plants were belt, the share of which is 95-97%. The widespread use of conveyor transport is due to its advantages over other modes of transport when moving large volumes of goods over short distances. These advantages include simplicity of design, reliability of operation, high productivity and low operating costs. In addition, the use of conveyor transport allows increasing labor productivity and the degree of automation of production, reducing the area of ​ ​ the plant by 10-15%, reducing the distance between workshops, simplifying transport communications, taking the plant-wide railway station of arrival outside the plant. The introduction of conveyor transport makes it possible to increase the degree of safety in transport.

The possibility of using conveyor transport in metallurgical plants increases even more with the development and creation of heat-resistant belts that allow transporting hot materials of metallurgical production of agglomerate, slag, coke, etc.

Development of schematic diagram of electric drive control

In accordance with the requirements of the task, schematic diagrams of electric drives are developed.

The main requirements for design are defined in GOST 2.755-87 "Symbols of conventional graphic in electrical diagrams. Switching and contact devices "[].

On each diagram, general marking of circuits (circuit sections) between elements is placed: odd digits in sections of positive polarity ("to the left") of relay coils and contactors, even digits in negative polarity ("to the right"). Circuits physically located within the same device (heat relay starter, push-button station, limit switch unit) need not be marked, since this connection has already been made in the design of the device.

For each electric drive, schematic diagrams are made separately and are given on separate sheets. For each scheme, the general marking starts again with one. The designations of the devices on each schematic diagram should differ, for example: 1QF1, 2QF1, 3QF1, where the first digit is the number of the circuit (electric drive), the last digit is the number of the device on the diagram.

For contacts of key switches, multi-position switches on diagrams, briefly specify the function, for example: "Start," "Stop," "Manual," "Automatic," "Forward," "Back," etc.

If the circuit diagram of this electric drive uses the contacts of the devices from the circuit of another electric drive, then this should be indicated on the circuit, making a extension line with the inscription, for example, of such content "from the circuit 1M."

A schematic diagram of the conveyor is given in Appendix.

Operation of conveyor circuit diagram:

By switching on the QF3 circuit breaker, supply power to the control circuits, by pressing the SB0 button, the HL0 lamp and the HS siren are powered, signalling the intention to start the conveyor.

Automatic start is carried out by pressing the SB1 button, receives power from the K1 relay, goes on self-energizing, closes its contacts in the KM1 starter circuit and in the KT1 time relay circuit, contacts in the K2, K4 relay circuits are also opened to block them for the time of automatic start-up and unlocks the K3 relay circuit by closing the K1 contact. After receiving power, the starter KM1 closes its power contacts and the engine M1 starts working. The time switch KT1, having received power, also operates and begins the minute countdown, upon its completion, the contact KT1 in the KM2 starter circuit is closed. After receiving power, the KM2 starter closes its power contacts in the circuit and the M2 engine starts working. In this case, the cycle of automatic switching on is completed.

Automatic stop is carried out by pressing the SB4 button, receives power from the K3 relay, goes on self-energizing, closes its contact in the KT2 time relay circuit, and opens the contact in the KT1 time relay circuit. Having lost power to the time relay KT1 opens its contact in the KM2 starter circuit, it in turn, having lost power, opens its power contacts and the motor M2 stops working. The time relay KT2, having received power supply, operates and begins the minute countdown, upon its completion, the contact KT2 in the relay circuit K1 opens. Having lost power, relay K1 opens its contact in the KM1 starter circuit - engine M1 stops operating. Contact K1 in the circuit of relay K3 opens, it in turn, having lost power, opens its contact in the circuit of time relay KT2. The circuit is reset.

Separate local control of electric drives is exercised by pressing the SB3, SB2 buttons for start-up, a stop of the M1 engine and the SB6, SB5 button for start-up, the M2 engine stop. Relays K2 and K4 are controlled respectively.

The schematic diagram provides light indication of all modes of operation of electric drives of the conveyor.

Electrical Layout and Electrical Routing

The basis in this case is the plan from the SOW. Performed at scale M 1:50. The location of the process equipment, existing distribution point, control cabinet (box, board) is already indicated in the task. The main reference document for this item is GOST 21.614-88 "Images of conventional graphic electrical equipment and wiring on plans."

The main (most common) options for laying cables: open along the wall at a safe height or in metal gas pipelines along the walls or (more often) in the floor.

At the first stage, a section of the electrical network from the switchgear to the control cabinet should be applied on the plan.

Then the sections from the cabinet to the electric drives are applied. If laying is done in pipes, the plan should indicate the location of the pipe exit with the elevation above the floor level. In the case of more than three pipe bends, an extension box (box) shall be provided.

The plan for laying the electrical networks of the conveyor line is given in the appendix.

Development of Cable Log

The cable log shows the types and lengths of power and control cables, pipes for their installation, etc .

The calculation should take into account vertical areas, as well as provide a margin of about 10% for cutting and other needs.

The height of the conveyor line room is 4 meters.

The cable log of the conveyor line is given in the appendix.

Pipeline Line Single Line Design

Based on the results of the previous paragraphs, a single-line diagram is shown, which shows the main power units (circuit breakers, starters, contactors), their type, nominal data and setpoints; specify the types, sections and quantities of power cables (if control cables are used as power cables, they should also be shown); method of connection of devices (as a rule, when selecting control cabinets, buses are shown, when selecting control boxes - loops).

It is also necessary to decide whether an input circuit breaker is used. If the existing distribution point is located in the same room (and relatively close), the input circuit breaker may not be used.

Otherwise, power shall be supplied to the cabinet buses via the input circuit breaker.

A single line diagram of the conveyor line is shown in Appendix.