Requirements for electrical diagrams and electrical diagrams of machines and installations

Automatic control circuits have certain requirements that must be met.

Requirements for schematic diagrams

The schematic diagram was developed based on the terms of reference for the design of electrical equipment and electrical automation.

Basic requirements for electrical circuits:

1. Compliance with the assignment

The scheme must ensure the operation of the unit in a certain sequence of operations in accordance with the sequence diagram of mechanisms in automatic, manual and regulation mode.

2. Reliability of the scheme

The reliability of the scheme is one of the most important requirements. It is determined by the following conditions:

• the quality of the selected equipment, i.e. its strength, durability, electrical resistance and compliance with environmental conditions.All electrical devices and elements of the electrical circuit must be selected taking into account the number and breaking capacity of the contacts, the time of retraction and fall of the magnetic systems, the switching frequency, the stable time delay, etc. It must be taken into account , that a circuit with less equipment is more reliable in operation;
• the minimum number of elements, devices with a short service life, serially connected contacts, moving wires;
• reliability of locks. Interlocks must be simple and exclude emergency consequences in the event of failure of one of the interlocking devices and in the event of a power failure.

3. Simplicity and economy of the scheme

Simplicity and cost-effectiveness are ensured by the use of simple, standard and inexpensive equipment, standardized nodes and blocks, minimizing circuit elements and device nomenclature. In some cases, schemes containing a large amount of simple off-the-shelf hardware are more cost-effective than schemes with less expensive or specialized hardware.

4. Ease of control and flexibility of the scheme

Convenience in control and flexibility of the electrical circuit of the machine or mechanism are achieved:

• reducing the number of controls, handles, buttons, switches and switches;
• the convenience of switching from one mode of operation to another, for example, from manual to automatic, from separate control of mechanisms to a combination and vice versa;
• the ability to restructure the circuit for a new technological cycle of equipment operation, as well as to turn off or introduce new interlocks without disrupting the main functions of the circuit;
• the ability to test the circuit with vented power circuits during the setup process.

Control levers must be provided as means of controlling manipulators, cargo and other machines, the movement of which imitates the movement of mechanisms.

5. Safety of work

The chain must exclude the possibility of false starts, violations of the sequence of mechanisms, the occurrence of accidents, rejection of products and injury to service personnel in the event of malfunctions of the chain:

• breaking or burning coils;
• welding contacts;
• interruptions or earthing in commutation;
• blown fuses;
• disappearance and renewal of tension;
• wrong actions of the operator.

Requirements for wiring diagrams

The wiring diagram is the main working diagram according to which the electrical equipment is installed, therefore, when compiling it, the following requirements must be observed:

• all connections in the diagram must be made taking into account the smallest amount of installation materials;
• the wiring diagram must be drawn up, taking into account the ease of installation of both individual panels and external connections;
• all external connections made through wires and cables must be reliably protected from mechanical damage and destruction of insulation from the effects of temperature, oils, acids and other factors;
• The electrical circuit as a whole should be drawn up taking into account the ease of use and safe maintenance of the relevant parts, apparatus and equipment included in it.