Isolation requirements of domestic and industrial switches

Safe operation of all types of electrical equipment depends on the actual state insulating materials which are incorporated into the design of the live parts of each mounting products. If the insulation is broken switches may fail, electricity, fire or even an accident.

We will tell you all about insulation types, ensuring full safety of using switching devices. In our proposed article described in detail the natural and synthetic, conventional and enhanced options. Are the features of the markings given advice to buyers.

Insulating electrical protection

Insulating materials protect the surrounding people and animals against electric shock. Conditions one: it is necessary to choose the correct consumable insulator, its shape, the thickness, the operating voltage parameters (it may be different as the design of the device).

In addition, a significant impact on the quality of the insulators may have a manufacturing or operating conditions of life of a complex electrical device. insulation quality, thickness and degree of electrical resistance must match the actual influence of the environment and the standard exploitation conditions.

Information about how to check the voltage in an electrical outlet, is contained in next articleWith which we encourage you to read.

The structure of the electrical insulation may be either a certain thickness of the dielectric layer and the structural shape (housing) made of dielectric material. Dielectric covered the whole surface of the current-carrying elements of the equipment, or only those conductive elements that are isolated from other parts of the structure.

Forms of insulation materials

Manufacturers that produce modern electrical switches that are used in residential, commercial and industrial buildings, the following types of electrical insulation: the working (primary), additional, double reinforced.

Working (main) isolation

This, in essence, the main protection of electrical installations, which gives them a normal and stable work, without causing short circuits, protects consumers from direct contact with live parts.

Working insulation, according to the specifications, the entire surface of wires, cables, other elements through which electric current flows must be covered. For example, the cords of electrical appliances always covered with insulation.

It must guarantee resistance to all potential external impacts that may arise in the process of exploitation in case of a synchronous electrical switches impact force fields, thermal heating, mechanical friction, corrosive environmental manifestations environment.

These factors adversely affect the electrical characteristics of the dielectric (insulating) materials also because they can be held irreversible deterioration of useful properties, that is, the insulation will be subject to rapid wear.

When it comes to commercial operation switches, the facility staff should periodically check the wear rate of the insulating structures in a timely manner to carry out preventive measures to control them protective properties.

Responsible maintaining a high level of insulation resistance reduces potentially possible earth fault body nullifies the electric shocks.

In small, little branched electric systems insulation resistance - a major safety factor. Control of basic insulation to acceptance is carried out immediately after installation work or repair, or periodic, carried out during the operation of the equipment at least 1 time per year.

In very humid halls control is carried out by 2 to 4 times a year in continuous operation. Measurements performed digital measuring device to monitor insulation - Megger.

Periodic monitoring of the insulation resistance on the set switches is performed on-site, where equipment over time is adversely affected by corrosive chemical fumes, moisture, dust and elevated temperatures. In this circuit isolation could broken. Instruments with damaged insulation are dangerous to human life.

Industry PUE (Rules for Electrical Installation), adopted in Russia, need to exercise regular measurement readings insulation resistance that is present in the power network from 1kV and higher.

The resistance of dielectric materials in the lighting installations in the region between 2 adjacent fuses must be <0.5 between any conductor and ground, and between any two wires Megohms.

This figure can not be applied in practice to air-wire electrical equipment external to the settings that located in extremely wet areas, because the resistance in these inconstant and depends on humidity indicators air.

It should be noted that if such facilities are no standards for insulation, then this factor should guide enterprises to consider and to take all measures for the safe operation of devices and more closely monitor the current state of materials isolation.

According to the SAE measurement of electric insulation resistance should be not less than a voltage of 500 V, and the test of insulation of multiconductor cables 6-10 kV.

Determination of current-carrying integrity of the cable conductors, check Megger their respective phases, should spend at least 2 people. Regulations require that one of them must have a tolerance of not lower IV group, and the second not lower group III.

Reasons for additional protection devices

Additional insulation is placed in electrical systems, having a working voltage up to 1 kV. It is an independent insulation, which will be installed along with the basic insulation of equipment, in order to difficult and dangerous cases, operation switches to protect against indirect contact with damaging elements.

Mainly, it serves as a counter electrocution, if you happen to damage the main insulation layer. A practical example of additional insulation - a plastic case circuit breaker, bushings, insulators, Insulating tubes, plastic tubes and other types of dielectrics.

For this type of insulation materials are used, which differ in their physical properties from the standard forms of dielectrics, which are the main electrical insulation.

This is done by taking into account the fact that even in the most adverse operating conditions or methods of storage electrical equipment would be unlikely to damage the main, working and additional insulation at the same time.

The advantage of double insulation

This potential danger to humans, as electric shock at the time of indirect contact with the elements of the equipment, can be significantly reduced by mounting a double insulation.

These durable protective materials are used in electrical devices where there is a voltage up to 1 kV. Here, put 2 degrees of protection - primary and secondary. Double insulated producers set at different electrical appliances: hand lamps, electric hand tool, in isolation transformers.

The practical meaning of double insulation concluded that besides the main, the dielectric layer. a second insulation layer placed on the conductive circuit portion. It protects a person from touching the metal conducting current which may well prove to be a high voltage.

To avoid this, a high-tech metal body covered with a layer of electrical insulator, handles, buttons and control panel make based dielectrics.

The appliances also isolate buttons, wires and a body shell made of metal. The disadvantage of such coatings is considered a relatively high mechanical fragility: there is a theoretical possibility of destruction of the insulation layer of the multiple mechanical influences.

Because of this metal, dead parts of electrical devices may be under voltage. It is therefore important to make measurements of the physical condition of the respective isolation devices in accordance with the circuit diagram.

It should be noted that the destruction of the second layer of insulation will not be able to influence the basic operation of instruments and, as a rule, is not detected at the time of inspection. Double insulated should be applied to the electrical equipment that operate in the consumer shall not be subjected to mechanical shocks and pressure on the current-carrying parts.

The most reliable protection of people will provide a way to double insulation on the equipment for which the body made of non-conductive, insulating material: it serves as a safeguard against the danger of electric shock.

A non-conductive enclosure device protects the current not only when dielectric breakdown in the product, but in case of accidental human contact with the current-carrying elements. In case the housing is broken the destruction constructive elements and arrangement of parts, and the device stops working.

If it is a defense, it works automatically and disables the affected product from the network. The devices feature a metal casing extra insulation perform special sleeve.

Through them, the network cable is held in a housing and insulating spacers separating the equipment from the motor housing. Nameplate electrical appliance with double insulation and carries the image of a special mark: a square inside the other square.

What is the reinforced insulation?

In terms of production, there are moments when the double insulation is problematic to apply on the design features of electrical equipment. For example, in circuit breakers, and other brush holder. Then you have to use a different type of protection - a reinforced insulation.

Reinforced insulation is placed on the electrical systems with rated voltage up to 1 kV. It is able to provide a degree of protection against electric shock, which is equivalent to double insulation properties.

According to the requirements of GOST 12.1.009-2009 SSBT reinforced insulation may have multiple dielectric layers, each of which can short-circuit testing separately to the sample, but only in the entire form.

Natural and synthetic insulators

Insulating materials, otherwise, dielectrics, in their origin are divided into natural (mica, wood, latex) and synthetic:

• Film, tape sealants based on polymers;
• Insulating lacquers, enamels - solutions of film-forming substances which are produced on the basis of organic solvents;
• insulating compounds, liquid hardening immediately after application to the conducting members. These materials do not contain any solvents in its composition, according to the destination divided into impregnating (coil processing appliances) and filling compositions that fill the cavity and the cable coupling devices and electrical units for the purpose sealing;
• insulating sheet and roll materials, which are composed of fibers impregnated both organic and inorganic origin. It can be paper, cardboard, fiber or fabric. They are made of wood, silk or cotton;
• varnished cloth with insulating properties - special plastic materials based on fabric impregnated with an electrically insulating composition which after hardening forms a film insulator.

Synthetic insulators are important for the reliable operation of electrical appliances and physico-chemical characteristics, given the particular production technology.

They are widely used in modern electrical and electronic industries for placing on the market of the following types of products:

• dielectric shell and the cable wires;
• frames electrical products, such as inductors, housing the rack, panel, etc .;
• electroadjusting reinforcement elements - distribution boxes, sockets, lamp sockets, cable connectors, switches and others.

Also produced radio electronic printed circuit boards, including the panels used for conductors unravel.

Classification of insulating material

Electrical insulation in household appliances is divided into appropriate classes:

• 0;
• 0I;
• I;
• II;
• III.

Devices with insulation class "0" have a working insulating layer, but without the use of elements for grounding. These structures have clamp for connection of the protective conductor.

Devices with insulation «0I» class have insulation + member for vanishing, but they contain a cable for connection to a power source that does not vanish veins.

Devices with «I» class insulation comprise a 3-wire power cord and plug 3 with contacts. Elektroustanovovchnye devices in this category are subject to Installation with a connection to ground.

Electrical appliances with insulation «II» class, that is double or reinforced, often found in household use. Such isolation reliably protect users from electric shock if the appliance main insulation damage happens.

Products, complete with a durable double-insulated power equipment is designated in the sign in, means: "isolation in isolation." Devices containing such a mark can not be annihilated and grounded.

All modern electrical appliances with class «III» insulation, can carry out their work in the networks of power, where there is a nominal voltage not exceeding 42 V.

Absolute safety when activated provide electrical proximity switches, With the features of the device, the operating principles and views which will introduce the recommended article us.

Conclusions and useful videos on the topic

Video contains instructions for using a popular brand megaohmmeter:

Small video overview insulation materials and methods for protecting current-carrying electrical installation hardware parts:

Particular types of insulation are used in the equipment of industrial switches, such as air or oil type. In everyday life, they are not used. If you had to deal with the violation of the isolation switches in production, you should contact your servicing electrical systems.

Please write comments, located in the block below. Share useful information on the topic of the article, which will be useful to site visitors. Ask questions on controversial and uncertain moments, share photos.