Control systems play a fundamental role in electrical engineering, distributing voltages between circuits, protecting circuits from becoming damaged, and ensuring system safety. Bespoke industrial control panels are made from a variety of components, each of which work together to sustain process outputs – and in this article, we’ll look at the main components we use in our customer’s systems.
The cabinet is the most obvious element of a control panel that people generally see. Generally, a mild steel box, although other materials such as plastic, GRP and stainless steel can be used. The cabinet provides a safe and secure environment within which the control panel’s switchgear can be housed. Bensons seeks to use standard, mass produced cabinets where possible to allow us to be cost effective, however, we have a range of suppliers who can provide us with bespoke cabinets to meet whatever requirements the customer may have.
To allow the door of a cabinet to be opened, then the circuitry inside must be electrically safe, i.e. turned off. This is the role of the isolator, effectively it is the power switch for the control panel, generally mounted on the cabinet door and designed in such a way that the door can only be opened with the isolator in the ‘off’ position.
Different circuits and components operate at different voltages, depending on the customer specification. Transformers enable different AC voltages to be obtained from a single incoming power supply by stepping-up (increasing) or stepping-down (reducing) the AC voltage to the required level. A common example is to reduce an incoming 415 V voltage down to 24V AC power for a control circuit. Power supplies play a similar role in transforming an AC (alternating current) voltage to DC (direct current) voltage.
Fuses are single-use safety devices that shut off an electrical circuit to prevent it being overloaded by an excessive electrical current, caused by a current surge or short circuit for example. Fuses are designed to withstand a certain level of electrical current (measured in Amps) before burning out, and once tripped, each fuse will need to be replaced.
Circuit breakers are essential safety devices that prevent burnouts and damage to the control panel and the devices that they protect. Circuit breakers are switches, they protect a circuit and its components from becoming damaged by a surge, or excess electrical current. As with a fuse, they trip when they experience an excessive electrical current, however circuit breakers can be reset once they have tripped.
Terminals are generally the most prolific components within a control panel, they allow electricians and engineers to connect wires from assembled equipment to the input/output connections on other equipment, thereby creating a complete circuit. In addition, within a control panel, terminals allow wires to be joined together, directing electrical power from a power source to the various components that need it.
Programmable logic controllers are small, industrialised computers, developed to control a range of processes in industrial settings, such as operating a wave machine in a swimming pool or controlling a complex and intricate production process. PLCs are configured for use in specific industrial or commercial environments and may include a range of input and output devices to allow the status of a process to be monitored and controlled. An advanced Human Machine Interface (HMI) can be implemented through the use of an appropriate control display.
The reliability of a control panel is underpinned by the quality of the electrical connections between the components, these connections are made by cable and the crimps at either end. Cable types can be broadly split between tri-rated cable and Low Smoke Zero Halogen cable (LSZH). Tri-rated cable meets British (BS6231) American (UL1015) and Canadian (CSA C22.2) standards. Whilst Tri-rated cable is rated to high temperature and is flame retardant, LSZH cable is intended for use in applications where smoke emissions and toxic fumes could pose a risk to human health and/or vital equipment in the event of a fire. At either end of a cable, you will find a crimp. The purpose of the crimp is to facilitate a secure and reliable connection between the cable and component. The crimp is applied to the cable with a crimping tool. To ensure the highest quality, Bensons uses crimps and crimping tools from an acknowledged industry leader.
Most electrical control panels feature these or similar components, but that doesn’t make each control panel equal. The differences between industrial control panel manufacturers comes down to the quality of the components they use, their level of design expertise, and the emphasis they place on robust, high quality manufacturing techniques. This is often enough to set an efficient, safe, and reliable control panel apart from a poorly designed and low-performing system.
Having celebrated 60 years in business in 2021, Bensons are one of the UK’s foremost designers and manufacturers of bespoke industrial control panels, serving customers throughout the world in a wide range of business sectors. We deliver bespoke projects to our customer’s precise specifications, and are accustomed to working to tight timescales, with an unstinting commitment to quality. To find out more, or for advice on selecting the best control systems for your application, please call 01924 975578 today, or click here to send us a message.
A control panel ensures all the machinery requirements are fulfilled by controlling the various processes. It has a critical role in the industry as it helps control the complex functions of machinery. Control panels have a vast range of industrial applications, which include:
Many components and devices combine to make up the control panel and its operation. In this article, we will discuss exactly that.
Circuit BreakersCircuit breakers are crucial components of an electrical panel as they prevent the whole circuit from being damaged. When there is a situation where there is an excessive electrical current, this can cause overheating, which can damage the whole circuit. A circuit breaker disconnects the circuit by detecting a high current and stops the current flow. Most circuit breakers will consist of the main circuit breaker that can handle 120V-480V in most industrial applications. We recommend trying out the CSRB4P63A100 RCCB circuit breaker part of the Wintrip series of circuit breakers by C&S Electric.
TransformersTransformers are passive electrical devices primarily used to change AC voltages between circuits. It can both increase and reduce voltages. This is through primary and secondary coils that can cause mutual electromagnetic induction allowing power transfer without changing frequency. By converting incoming voltages, they can allow all devices connected to a control panel to use power. Incoming voltages are generally too high for standard devices and can damage. Transformers help reduce the voltage and provide a safe working environment for the control panel and its operators. Eutroniks manufactured control transformer is an excellent addition to your control panel.
Terminal BlocksTerminal blocks are insulated, modular blocks that serve as connection points to link multiple wires together. This can help organize wires coming from various sources to connect to other electrical devices. There are many different types of terminal blocks, but they consist of a conducting strip and a clamping component for the most part. An Elmex KUDF4 fuse terminal with a screw clamp is a reliable terminal block that you can use as part of your control panel.
Read more about terminal blocks, their types and applications here!
RelaysRelays are electromagnetic switches responsible for opening and closing circuits to turn a device on or off. A relay uses an electromagnet to allow low currents to activate high currents, which will change the circuit depending on the need. They are one of the more crucial components of an electrical control panel as they allow the controlling of other electrical instruments. Relays are mainly used for devices with low currents. We have a range of relays that you can try out, such as the Automatic Power Factor Controller provided by Nippen used in panels with capacitor banks and reactor banks.
Another type of relay used in control panels is an overload relay. An overload relay protects electric motors from overheating by preventing them from taking more current than they can. Some circuit breakers allow more amps than the total load rating of a motor, so an overload relay protects from such a situation. It will open or break the circuit to protect the motor by stopping the current.
Other types of Relays are UVR (Under voltage relay) and OVR (over-voltage relay) with ON/OFF delays which operate when the voltage across the relay’s coil drop or reach a certain voltage level. The relay contacts trip the circuit breaker. These are used as voltage protection devices to detect sudden voltage drops and short circuit faults. They are mostly used in alternators, busbars, and motors.
Other types of relays are Earth Leakage relays used with CBCTs (Core balance Current Transformer).
Learn more about relays, and the key points that differentiate them from contactors in this article- (Medium blog/ GoSwitchgear Blog).
Contactors are very similar to relays as they are also responsible for switching and controlling electrical circuits. However, what makes contactors different from relays, is that they are used for applications and devices with higher currents. For example, contactors control electric motors typically with high operating currents. Power contactors that are part of the Robusta series are a great example of contactors that can be part of an electrical control panel.
Read more about contactors, relays and the key difference between both instruments here!
Switch DisconnectorsSwitch disconnectors are crucial for a safe electrical working environment. They combine the properties of disconnectors and load switches. They are devices that consist of movable contacts that can be mechanically closed to form a circuit and mechanically closed to break a current. The function of a switch disconnector is to break load currents up to their rated normal current. They make and break under load conditions that provide safety and isolation for circuits, and are especially beneficial for machine control circuits. You can find switch disconnectors in different styles and form factors. The CSSD400DM3U switch disconnector is an excellent switch disconnector that you can integrate into your control panel.
Programmable Logic Controller (PLC)A PLC is essentially a CPU installed inside the control panel that acts as its brains. PLCs control various equipment and mechanical processes by monitoring sensor inputs and control outputs. This includes electrical equipment like lights, motors, solenoids, and much more. PLCs are generally designed for factories and industries with a lot of noise and vibrations and may not be necessary for simpler control panels.
Motor DrivesMotor drives are known by many other names, such as adjustable speed drives, variable frequency drives, and inverters. They come in various shapes and sizes because many motors exist for specific functions. Motor drives help control the speed of a motor by varying the frequency and voltage of an electric motor’s power supply. This makes it possible to enhance process control, generate energy efficiently, and reduce energy use. This results in optimizing processes involved in various applications that rely on electric motors. In short, the primary purpose of a motor drive is to operate any connected motor. Standard motor drives that are commonly used are soft starters and VFDs.
EnclosuresEnclosures are metal boxes that house the control panel and are generally aluminum or stainless steel. You may have likely seen these enclosures in several places but not peered inside at the electrical components housed within. Various classifications are generally printed on the doors of the control panel. The purpose of these is to help determine properties such as indoor or outdoor use, waterproofing, fire proofing, among other things.
Back PanelsBack panels are mounted sheets inside the closure made of metal, providing structural support for the wiring ducts and rail mounting. The rail mounting allows for the mounting of electrical devices while wiring ducts help organize and route the wires connected to the control panel. This helps control the electrical noise between devices of the control panel houses within the enclosure.
You can purchase wiring ducts/ slotted cable trunking by KableKonnect under the ‘Accessories’ category on our website.
Wiring and CablesLast but not least, we have the wiring itself that is a crucial aspect of the control panel as it helps connect everything. There are various forms of wiring inside a control panel as all components and devices will have different types of connections. Additionally, cables are needed for connections from the control panel to other devices, and these will be much thicker than general wiring. In essence, they are the heart and soul of any electrical component or device. You can find PVC single core copper cables of various sizes on our website for your control panel building requirements.
The bottom lineControl panels are crucial for industries and factories, among other applications, as they help control the various electrical processes part of a system. There are so many electrical processes that wouldn’t function properly if not for the control panel, which ensures everything runs smoothly and safely. We have discussed the various significant components of an electrical control panel, each having a specific purpose. We hope this article has provided you with insight to comprehend the utility of instruments used in control panel building.