Industrial Switches

Industrial Switches - Types and Features

Switches are among the most basic of electronic components. In the most basic sense, a switch has contacts that can be opened or closed. When these contacts are closed, current can flow across the contacts, powering the circuit to which the switch is attached. The switch may be opened or closed by various means. According to the Electronics All-In-One Desk Reference for Dummies, the way in which a switch is thrown or opened is one of the ways that a switch can be categorized, as you will see later in this article.

What Are Industrial Switches?

The information contained in this article refers to switches that are specifically designed to open or close electronic circuits. As Neteon.net demonstrates, a great deal of information about electronic switches will tend to be information about Ethernet switches, which are switches used on computer networks. The following information is concerned solely with switches that are used to open and close circuits on industrial machinery and in other industrial applications. Industrial switches are no different from any other type of switch, save for the fact that they are designed with the harsh conditions under which they are used in mind. Industrial switches have to be stronger, able to be thrown many times without breaking down and, in many cases, they have specific features that allow them to be thrown based on input from machinery, electronic devices and so forth. Many industrial switches will be designed with features that are included with specific types of operating conditions in mind. For instance, switches with waterproof caps are not uncommon and have obvious usage in environments such as car washes, pressure washing stations, water treatment plants and so forth.

History

Switches are such basic electronic components that, in reality, most anything that allows an operator to open or close any electronic circuit in a way that doesn't require rewiring can be considered a switch. The history of the switch really starts with John Homes, however, who invented the modern light switch in the late 1800s. This was the first product that allowed people to conveniently open and close circuits and, of course, it has never gone away since its invention. Over time, more sophisticated applications for switches have necessitated the development of more sophisticated switches. For example, a mercury switch can be used in applications as wide-ranging as simple tilt alarms found in vending machines to life and death applications, such as controlling certain types of aircraft. New applications, new materials and other technological advancements have all played into the invention of new types of switches.

Who Uses Them?

Every industry uses switches. Given that a switch covers everything from the on-off switch for the lights on a wall to gigantic switches that are used on high-powered equipment, every single industry in the world uses switches. Industries, however, may vary tremendously in terms of what types of switches they use. The types of switches will also vary depending upon the exact scenario in which they are being employed. For instance, a company that has a facility with a separate control center will likely have modular switches installed on their control boards. They may also have gigantic switches installed right on the machinery itself. Because these are such basic electronic components, however, it's a given that any piece of electronic hardware is likely to have a switch on it, whether it is a manually activated switch or an automatically activated switch.

Overview of the Various Industrial Switches.

The following types of switches are likely to be found in most industrial settings. In some applications, the switches may constitute one of several different options and, in others, they may be the only option that can do the job.

Fused Switch Disconnectors

A fused switch disconnector is used as a protective device on circuitry. In essence, it combines the functionalities of a disconnector, a switch and a fuse all into one. These are oftentimes provided with blade style contacts, owing to their usage.

Non-Fused Switch Disconnectors

A nonfused disconnector provides a way to reliably deenergize a circuit. They are oftentimes employed for maintenance and for isolation purposes. These switches typically function separately from the master switch on a circuit, allowing the circuit to be deenergized, even if the master switch is still flipped to the on position. The disconnector is typically employed after the circuit has been deenergized by other means. This makes it different than a circuit breaker. Disconnectors are safety devices more than anything else and, in many cases, they are provided with accommodations for a padlock so that they can be safely locked out if somebody is working on the circuit and that circuit being reenergized would pose a safety hazard.

Interlock Switches

Interlock switches are used primarily as safety devices. These devices are oftentimes employed on industrial equipment that needs guarding to be used safely. When the guards open, the switch is tripped, opening the circuit and shutting the machinery down.

Key Switches

Key switches come in two primary types. Some are switches that have a separate guard installed over the top of the switch, which is fastened down with a lock and key, preventing tampering. Other switches actually use a key as the main means of throwing the switch. An operator must be provided with the correct key, and must insert that key into the switch to actually turn it, bringing the contacts together and powering the circuit or separating them and taking power away from the circuit.

Limit Switches

A limit switch is a type of switch that takes mechanical action and uses that to open or close the contacts in the switch. For example, HVAC equipment may have a limit switch installed on it that monitors the position of a vent or another component in the heating system and that opens or closes a switch depending upon that position.

Limit Switch Accessories

Limit switch accessories are generally used to allow easier installation of these vital devices. They may, for example, provide the fastening equipment necessary to install the limit switch on HVAC equipment, a common application. For more information on limit switches themselves, see below.

Mercury Tilt Switches

Mercury tilt switches have advantages that make them suitable for very hazardous applications. They are completely enclosed, so there is no hazard of explosion or fire from arcing on high-power electrical circuitry. The connection that they provide does not bounce, which means that they're suitable for use in environments where vibration is a concern. Mercury tilt switches work by using mercury as a means of conducting electricity from one pole of the switch to the other. They are usually glass devices and they can have more than two contacts in them, depending upon the application. When the glass bulb that contains the mercury is tilted, the mercury comes into contact with both – or all – of the poles on the switch, allowing electricity to flow across.

Non-Mercury Tilt Switches

Mercury is an incredibly dangerous substance, and it can have serious effects on the environment and the things that live within it. For that reason, tilt switches that do not employ that particular element are available. These use typically non-toxic substances to serve the same purpose. Mercury would normally be used to conduct electricity between the two contacts in a tilt switch. Non-mercury designs allow this to be done with substances that are far safer.

Photovoltaic Switch Disconnectors

One of the hazards brought about to emergency personnel by the advent of solar power is having power flowing through a circuit even when the mains to a building have been cut. A photovoltaic switch disconnector provides a way to eliminate this danger. It functions to disconnect all of the photovoltaic connections in a circuit under emergency conditions. Some of these devices are equipped with lights that make it easier for firefighters and other emergency personnel to ascertain that the circuit has been completely deenergized.

Precision Position Switches

Precision position switches are limit switches that are designed to work under conditions where the exact position of a mechanical part or anything else that is being monitored needs to be ascertained. These function in the same way as limit switches, excepting that they are far more precise in their operation.

Push Buttons

Push buttons are among the most common types of switches in the world. They can be made in any number of configurations, from simple on-off switches to multistate switches that allow the condition of the circuit to be switched between several different variables by pushing the button repeatedly. These buttons are found in a huge number of different industrial applications and, of course, are common features on consumer appliances and in households. These switches are often designed in a modular fashion, allowing them to be easily inserted and removed from a control board.

Push Button Accessories

Push button switches are oftentimes supplied with various accessories appropriate to their usage. For instance, they may be part of modular equipment that can be easily installed or removed from a control board. Push button accessories include everything from keyed devices that make it impossible for somebody without clearance to activate the switch to color-coded switch covers that make it easier for people to identify which switch is which.

 

Push Button Enclosures

Push button enclosures are typically designed to hold several different push button switches, isolating them from the environment and making them easily accessible. Some of these enclosures are designed to be mounted to a wall and others are designed to be hung directly from wires, such as the on/off switches typically seen on large machinery. The switches come in a variety of different designs, colors and with various environments in mind.

Enclosed Push Button Stations

Enclosed push button stations are common features in most industrial settings. These are switches that are self-contained, being protected by a metal or plastic housing. They typically have one switch protruding from them, usually a push button model, and are oftentimes used to start or stop machinery. In some cases, the switches are enhanced with cover plates that allow the actual push button component to be protected against accidental switching.

Push Button Pendant Stations

Push button pendant stations are designed to hang freely from wires and provide a handheld way to control machinery and other equipment. These are typically designed with very challenging environments in mind and are made out of appropriate materials, such as various rubbers, plastics and other materials that are resistant to environmental hazards.

Reed Switches

Reed switches are devices that open or close based on the condition of a magnetic field. They are typically enclosed in glass and, when a magnetic field is introduced, the switch closes. These are oftentimes employed in burglar alarms. They are oftentimes used as proximity switches, as well.

Replacement Handles & Accessories

While switches may be incredibly durable devices, the throws, handles and other operating parts on them sometimes break. Replacement handles and accessories provide an easy way for maintenance personnel to get a switch up and running again without having to replace the electronic components themselves.

Rotary Switches

Rotary switches are the go-to choice when more than two different positions are required on the switching hardware. These devices are frequently found on radios and television sets, though they have been largely displaced by digital equivalents. Some of these switches can be configured by the user.

Rotary Switch Accessories

Rotary switch accessories include knobs, casings and other accessories that help to protect the switch and to make it easier to use.

Thermistors

A thermistor is a special type of resistor that increases or decreases its resistance in the presence of heat. These are sometimes used as switches for safety purposes, as they can cut a circuit in the event that it overheats.

 

Thermostats

Thermostats are common devices, found in households and in industrial applications. They control switch that is closed or open based on temperature input. These vary in design from very simple analog devices to incredibly sophisticated digital devices that are able to open or close a circuit based on very precise measurements of temperature.