Designing Control Panel
Control Panel Components
Any industrial control panel is built with many components just like an electronic circuit board. There are modules for power conversion and distribution, there are energy dissipation and storage modules, switching components at many kHZ, safety modules to protect users as well as electronic components, lots of wires, nuts and bolts, list goes on. We might end up creating a very hostile environment within control panel if we are not careful placing compatible components in neighbourhood and ensure components get supply at right amount and we have favourable climatic conditions for components to live long. These are extremely explosive components and a simple careless mistake could easily cause fire to say the least.
Inside Control Panel
Some common components that we might discover within control panel are Transformers, Fuses, Circuit Breakers, Relays, Contactors, Power Supplies, Fans, Programmable Logic Controllers PLCs, Electrical Control Drives, Filters, Chokes, I/O cards, Signal Amplifiers, Trunking, Terminals, Wiring, Operator Screen HMI. It is really difficult to make a complete list as the innovation results in new components and control panel design differs based on application requirements. Nevertheless, I have briefly discussed some key components and their role in the control panel.
Miniature Circuit Breaker MCBs
Miniature Circuit Breakers provide better protection as compared to the fuses as they could always be switched on once these are tripped. Similar to fuses, these provide protection to electrical circuit when excessive current attempts to pass through the circuit. These also have breaking capacity up to 16kA which means maximum potential current likely to flow in an unfortunate event of a short-circuit. MCBs are time-operated and do not offer transient response to excessive current unlike fuses. Therefore, these are perfect as protection for three-phase motors which produce overload current of nearly 1.5 times the rated current value. In case of overload, MCB trip between 2s to 2 minutes based on type and over load current. There are three types of MCBs – B, C and D type. The biggest difference between these is maximum overload current device would allow prior tripping. B types are usually 3 to 5 times rated MCB current and ideal for household applications. C types are generally used for inductive loads such as motors and allow 5 to 10 times overload current prior tripper. Where as C type offers 10 to 20 times rated current and usually used for UPS systems or very large motors. MCBs are also available as single pole, two pole or three poles arrangement to protect supply phases.
As discussed, it requires great care to build control panel for industrial applications. In this article, I have merely scraped through one of the component, MCBs – that is generously distributed in control panel cabinets. I hope this articles give a good appreciation for the work that is required to put together a safe and reliable control panel cabinet.