Review of the Most Important Industrial Switches
For the management of electrical devices, consumers utilize various tools. One of the simple and effective ways to control electrical devices is the use of various industrial switches. A switch acts as a key tool that, by changing its state, provides electrical connection or disconnection and can also change the state of the electrical circuit. This simple method allows consumers to easily and precisely manage their devices, optimizing energy consumption.
What is an Industrial Switch?
Industrial switches are mainly produced in various shapes based on their location and type of use. For instance, based on external structure, they are designed and manufactured to resist various environmental factors such as moisture, dryness, heat, or places with a risk of impact. Additionally, from the perspective of current flow, these switches are produced with different amperages, ranging from a few amps to several thousand amps. This diversity in the design and manufacture of industrial switches enables the selection of the best option for each specific need.
Types of Industrial Switches
The mechanism of industrial switches varies and is produced in various categories. However, generally, industrial switches can be divided into three main categories: simple or manual switches, compound switches, and protective switches.
The change in the state of industrial switches is caused by mechanical force applied to various handles. This mechanical force can be applied directly to the switch or can change the state of the switches using other forms of energy such as electricity. From this perspective, switches can be divided into two categories: simple switches and compound switches.
Simple Switches
Simple switches are a type of industrial switch that utilizes mechanical energy to change the state directly on the switch itself. These switches are made in various forms such as single-pole, double-pole, triple-pole, etc., and are divided into several categories based on the structure and the capability of voltage interruption and connection. The classification of simple switches includes momentary and permanent types. For momentary operations, there is no need for continuous mechanical force like a doorbell handle. However, permanent simple switches require continuous force to change the state from connection to disconnection or vice versa.
Manual Momentary Switches
Manual momentary switches are active as long as force is applied to them, and energy is supplied to them. They remain in an active state as long as force is applied, and the circuit is connected. By removing the force from the switch, it returns to its initial state, and the circuit is disconnected. For the operation of momentary switches, continuous mechanical force is required.
Manual Permanent Switches
Manual permanent switches are a type of industrial switch that requires continuous force to change the state from connection to disconnection or vice versa. These switches are operated by humans through hand force, changing their state by applying mechanical force. In other words, these switches are connected or disconnected by hand force. One of the main challenges of these switches is high failure rates, low speed in circuit interruption and connection, constant need for repair and maintenance, life-threatening risks for operators, constant consumer connection to electricity, and the need for high energy for connection and disconnection.
In summary, industrial switches play a vital role in electrical systems with their various applications and are designed and manufactured based on the diverse requirements of industries.
Industrial Push Buttons
Industrial push buttons, also known as pushbutton switches, are pressure tools used to start and stop various equipment in industrial environments. These switches are used for various functions such as start-stop, emergency stop, or specific performance due to their unique operation. Push buttons are divided into two types:
1. Start Push Button (NO – Normally Open): Connects the equipment when the button is pressed.
2. Stop Push Button (NC – Normally Closed): Disconnects the equipment when the button is pressed.
These efficient tools are widely employed in industry due to their reliability and high performance. Additionally, these buttons are crucial elements in safety and equipment control and hold significant importance in various industries, including manufacturing, energy, and automation.
Permanent Manual Switches
Permanent manual switches remain in their state until momentary force is applied to them, and to change their state, they require pressing the button again. In other words, these switches always require momentary force to change their state.
Permanent manual switches come in various types. The first category is used in the building electrical field, such as single-pole switches, double-pole switches, cross switches, and three-phase switches. The second category is used in industrial electricity, such as selector switches.
These permanent switches are produced with different internal structures, including lever, roller, tongue, selector switch, and rotary switch. This variety in structure makes these switches suitable for various needs in different industries, and they are highlighted as essential elements in control and safety systems.
Lever Switch
The lever switch is one of the simplest and most commonly used types of industrial switches. This switch utilizes a rotating axis and blade-shaped levers. By rotating the axis using the lever, the blades are connected to fixed contacts.
The lever switch is mainly used to separate circuits with low current and is sometimes referred to as a knife switch or blade switch in the industry. In these switches, by closing the circuit with a thin wire, fuse action is performed for each blade.
In higher-power switches, they use knife fuses (NH) under the blade. Some types of switches perform the function of disconnecting and connecting simultaneously for all three phases using blade movement. A tool called a fuse puller is used to replace and remove knife fuses.
Roller Switch
The roller switch is another category of simple industrial switches, and its structure consists of an insulating cylinder that moves around an axis in a circular motion. In this switch, conductive parts are placed as strips on the cylinder, and by moving the cylinder around its axis, they can connect or disconnect fixed contacts.
When the recessed parts of the cylinder or roller are in front of the fixed contacts, a disconnect state is created. If the protruding parts are in front of the contacts, they connect them. Due to the repeated contact of the conductive parts with the contacts, the useful life of this switch may be limited.
Tongue Switch
The tongue switch is a simple type of industrial switch consisting of a lever arm, a tongue-shaped plate, movable and fixed contacts, and a spring. This switch, with the combination of different elements, offers various operational capabilities. Unlike roller switches that may have a limited lifespan due to the wear of the conductive strip and fixed contacts, the tongue switch provides a longer life and durability with proper design and without mechanical friction.
In this switch, the cylinder is designed with protrusions and recesses that allow the cylinder to move around its axis and lift the tongues up and down. This frictionless mechanical motion performs the function of connecting and disconnecting contacts, leading to an increased lifespan and efficiency of the switch. This type of switch is produced as a flush or surface-mounted panel and is commonly referred to as a selector switch.
These translations provide an overview of different types of industrial switches and their applications. If you have specific questions or need further details on any particular type of switch, feel free to ask!
Selector Switch
A selector switch is an electromechanical device designed to manually open and close electrical circuits. This device is used in stepped voltage sources to select different voltages for the output.
Selector switches are designed as keys used to select different operating modes, such as the two-position three-phase rotary switch used to start three-phase motors in star or delta configuration. These selector switches are used to manually control the opening and closing of contacts and are available in fixed, spring return, and key-operated types.
Selector switches are used to measure the voltage between different phases and the voltage of each phase relative to the zero wire. Another type of these switches is the selector switch installed on multimeters, allowing the measurement of voltage, current, or resistance at various ranges. Additionally, the fan coil switch is also a selector switch that can set the motor to low, medium, or high-speed rotation or turn it off.
Rotary Switch
A rotary switch is a switch with the ability to control a circuit through its rotation. This switch consists of an axis and contact arms, and by rotating the switch axis clockwise or counterclockwise, the state of the contacts changes.
Rotary switches, also known as rotary selectors, are designed and produced for electrical currents with low values, up to approximately 100 amps, and are usually capable of disconnecting under load. This type of switch can be used for both AC and DC currents and is available in various types for various applications.
Some rotary switches, like two-position three-phase rotary switches for star and delta configurations, act as a type of selector switch, enabling the starting of a motor in star configuration and then changing to delta configuration. These switches offer various modes, including three, four, and five positions.
Compound Switches
Compound switches are a different category of industrial switches that use mechanical force to change states through intermediate energy sources such as electromagnetic, thermal, cooling, light, and other energies.
This category includes various relays such as bimetal relays, automatic switches, and contactors (magnetic switches). The use of contactors allows the programming and control of the operation of devices and electrical equipment both automatically and manually. Control and power circuits are tools that can be used to program and control the operation of many electrical devices and equipment. Various tools are used to create control circuits, with contactors being the most important.
Other industrial switches used in control circuits include thermal relays or bimetal relays, signal lamps, fuses, limit switches, pressure switches, float switches, timers, thermal function switches, electric eyes, and run function switches (jog switches). Let’s explore some of these compound switches in more detail.
Contactor
A contactor is a type of magnetic switch used to open and close circuits and control electrical processes. This switch is made up of two E or U-shaped cores, one stationary and the other movable, separated by a spring.
In the stationary core, there is a coil or winding. When the coil is energized, electromagnetic force is created in the stationary core. This force, using magnetic properties, restrains the spring force and attracts the movable core towards the stationary core. This action causes the contacts to connect to each other. In other words, the main contacts of the contactor close, and the auxiliary contacts change state; meaning normally open contacts close, and normally closed contacts open.
Magnetic Motor Protection Switches
Magnetic motor protection switches are vital tools in protecting electrical equipment such as electric motors, asynchronous motors, and induction motors. Faced with excess current, these switches work to prevent damage to the motors. Electrical protection of circuits should be arranged in such a way that in motor startup, the startup current (which may be several times the motor’s rated current) quickly disconnects the circuit, preventing harm to the motor.
These protective tools should be selected in a way that during motor startup, the startup current causes the circuit to quickly disconnect. For example, Schneider’s thermal relay has a bimetal that heats up if the current exceeds the rated limit, quickly disconnecting the circuit. Although the bimetal does not have rapid functionality, its average response time is short enough to prevent motor damage.
Bimetal
Bimetal, or bimetal relay, is a vital tool for protecting electric motors against increased loads and is connected to contactors. The operation of bimetal Schneider is based on the principle that if a current greater than the set limit passes through it, it acts as a thermal element and quickly disconnects the current.
The relay has a thermal element that, during the nominal current, is typically at around 40 degrees Celsius. If the current exceeds the nominal value, and heat is produced in the thermal element, the temperature exceeds the set value of the relay, and the relay acts. This working method, based on temperature sensitivity, prevents damage caused by increased heat and provides confidence to the motor.
Safety Switches
Safety switches are vital tools housed in a separate enclosure. This separate enclosure enhances safety for personnel in cases of accidental contact with high-voltage electrical connections, protecting the switch from contaminants and weather effects. The degree of protection is determined by various features assigned to the enclosure. Safety switches are often used in two main forms:
1. Power disconnect
2. Breaker and protector
Some safety switches come with fuses, while others lack fuses and only include a switch, associated connections, and an internal interlock. This family of switches is produced in two duty categories: normal duty and heavy-duty. Safety switches enable the disconnection and connection of loads from the power source during motor startup, such as in woodworking machines that require the use of safety switches according to NEC standards.
According to this standard, disconnects should be located on the motor and equipment side, meaning in front of the operator’s eyes, and their distance from the operator should not exceed 50 feet. These switches support rated currents in the range of 16 to 4000 amps. With the switch turned off, the input power is cut off, allowing the operator to confidently service the machine.
Automatic Switch
An automatic or automatic switch is a powerful tool that can control the disconnection and connection of power while simultaneously being responsible for protection against excessive current and short circuits. This type of switch is used in situations where there is a need for equipment protection, including lighting installations, wires, cables, and industrial machinery against excess current, short circuits, etc.
The advantages of automatic switches over fuses and manual switches include:
1. Quick service readiness: The automatic switch quickly becomes ready for operation after circuit interruption due to high current or other factors.
2. Remote control: Through auxiliary contacts embedded in them, the status of the switch, such as open, closed, or fault occurrence, can be detected using appropriate signals and sent to the control room.
The structure of these switches is such that if the switch is short-circuited in a circuit, immediately after closing the switch, the relay disconnects the excess current quickly. In most cases, the automatic switch is not only used as a tool for circuit interruption and connection but also performs a protective function.
Miniature Switch
Miniature switches, as examples of automatic or self-operating switches, are composed of components such as a switch, a fast-acting magnetic current relay, and a thermal relay or bimetal. These switches are designed to manage nominal currents with values ranging from low to 63 amps. Protection against overload and short circuit is also present in some models, where protection specifications are usually fixed.
These switches are often used in household applications and have the ability to disconnect with lower power than other automatic switches. Types B and C of these switches are the most common. Type B is more commonly used in lighting and has a fast response, while Type C is suitable for starting motor devices with a slow performance. These switches are made in single-pole, double-pole, and three-pole configurations.
Miniature switches are divided into several main classes, with their difference lying in the tolerance of short-circuit currents:
1. Class A: These switches are very sensitive and can tolerate up to twice the rated current. This feature makes them a suitable option for applications that require high sensitivity.
2. Class B: Used for non-motor loads, such as lighting, and can tolerate 3 to 5 times the rated current. This class serves as a broad option for lighting and non-motor load control applications.
3. Class C: Suitable for motor loads and can tolerate 5 to 10 times the rated current. These switches serve well in controlling motors and related equipment.
4. Class D: This class is suitable for the protection of capacitive loads or loads with surge currents and can tolerate 10 to 20 times the rated current. Therefore, it is a suitable choice for cases requiring resistance to high-intensity currents.
Residual Current Device (RCD)
The Residual Current Device (RCD), also known as a ground fault circuit interrupter (GFCI), is a vital device in electrical systems that is divided into two categories: residential (single-phase) and industrial (three-phase). This device, in addition to protecting individuals against direct and indirect contact with electricity, prevents leakage current and protects industrial devices and equipment. The RCD provides safety for individuals, especially when facing hazards resulting from electrical leakage.
The main tool in this protection device is a circuit called the Residual Current Circuit Breaker (RCCB). This circuit compares the input current with the output current and, if the leakage current exceeds the specified sensitivity limit, disconnects the circuit. This action helps ensure the safety of individuals and the protection of equipment.
A specific type of RCD known as RCCBO or Combined Residual Current Device combines a miniature switch and an RCD. This type of RCD disconnects hazardous contact voltages in a short period, up to 2.0 seconds. It has a simple installation and wiring and is also economically viable.
Fuse Switch
The fuse switch is a vital industrial tool that allows the separation of fuses from the circuit. The action of disconnecting and connecting fuses is performed manually using this switch, facilitating the easy replacement of fuses. These switches are primarily installed on electrical panels and are used to prevent hazards when replacing fuses in low-voltage networks.
Economically, these switches are a superior choice. They are mainly installed on electrical panels and, by allowing fuse replacement without the need to open the panel, they prevent associated risks. Fuse switches are widely used in power distribution in factories, lighting systems, transformer substations, and energy transmission lines.
One notable feature of these switches is that there is no need to open the panel for fuse replacement, preventing potential hazards. These switches are cost-effective and occupy minimal space dimensionally. Using this type of switch in power distribution, especially where high-speed power interruption is crucial, offers significant advantages over traditional fuses.
The components of a fuse switch include a fixed base, a moving part and fuse holder, terminals and installation holes on the busbar, input and output cable connection terminals, and fuse installation contacts. These components, along with the disconnect and connect function, allow users to replace fuses without risk and with ease.
Industrial Three-Phase Switch
Industrial three-phase switches, including disconnectors and section switches, are essential tools in three-phase circuits, especially those with high voltage. These switches play a vital role in managing energy in complex systems with high voltage.
The power switch or section switch, as a voltage isolator, does not allow current to pass through the circuit to be disconnected or connected (as long as the default current has been previously disconnected). Equipped with arc prevention systems, these switches, unlike disconnectors (power switches), have the ability to disconnect and connect under load. This feature is particularly important in ensuring additional safety during moments of contact separation, preventing the creation of severe electric arcs.
The applications of three-phase switches are extensive and essential, including connecting three-phase consumers to the network based on the consumer’s internal connection type, starting three-phase asynchronous motors in star or delta configuration, reversing the rotation direction of three-phase motors, adjusting the speed or revolutions of three-phase asynchronous motors, and braking three-phase motors.
Three-phase industrial switches play a crucial role in controlling and managing energy in high-voltage complex systems and are considered fundamental components in the electrical industry.
Power Switch
The power switch or section switch, acting as a voltage isolator, does not allow current to pass through the circuit to be disconnected or connected (as long as the default current has been previously disconnected). Unlike disconnectors (power switches), these switches have the ability to disconnect and connect under load. This feature is of great importance as it ensures the prevention of severe electric arcs, especially during moments of contact separation.
In conclusion, this article has explored various types of electrical switches, including magnetic, miniature, automatic, safety, bimetallic, and fuse switches. Each type of switch has its specific applications and features. Additionally, the importance of the life protector switch and its role in protecting individuals and electrical equipment has been discussed. Finally, three-phase switches and power switches have been examined in terms of their applications and unique characteristics.
