Circuit Protection for Power Distribution

When designing control systems, power distribution is an important factor for consideration. The features of distribution included in a control panel setup ultimately determine the operational efficiency, productivity and safety of the intended working environment. It goes without saying that the power distribution designs need to be thorough, so that the entire panel is protected from overloads and faults, as well as protecting the user.

The issue that electrical engineers face, is that there isn’t a definite set of criteria to follow when designing the power distribution elements within a control panel. What we do have, are the British and European standards and their corresponding codes. The rest really boils down to experience and intuition, the latter of which is earned through years of practice.

DualTEC’s electrical engineers have a collective knowledge that far surpasses our impressive 15 years in business, and it is that experience which enables us to design and build products that make circuit protection for power distribution an inherent part of all our control panels.

Considerations for power distribution in control panel design

There are two overarching goals when designing power distribution into a panel build. There needs to be an ability to localise and isolate the fault in question, this then prevents or at least minimises any needless loss of power.

Whether the control system is intended to govern automated factory equipment or route power across the national grid, short circuits and overloads are to be expected during a building’s operational life. To avoid damage to either the internal parts of the control panel, machinery within the building or both – localising and isolating the fault is essential.

So what protection should be included in the control panel design?

The two most common forms of circuit protection for power distribution in control panels are overcurrent protection and ground-fault protection.

A ground-fault is where a break in the circuit ‘grounds-out’ or connects with the grounding point, usually the equipment frame. This is normally as a result of faulty or broken insulation, effectively making any conducive element in the panel ‘live’ – including the user. As the name would suggest, overcurrent is where more electricity than intended is passed through a conductor, generating excess heat which in turn increases the risk of component damage or even fire.

Protection against overcurrent comes in the form of specific devices. Circuit breakers, relays and fuses are the three most basic and fundamental OCPDs (overcurrent protection devices) that should be incorporated into any control system. These components are intended to break, isolate or blow whenever overcurrent is present.

Fuses are the simplest form of protection, consisting of a single strand of wire with an amperage rating higher than the recommended load for the circuit. Overcurrent increases the current by at least four times the recommended load, so under these conditions the fuse blows and breaks the circuit. Circuit breakers work on a similar basis, with the key difference being that the ‘break’ is reversible, unlike fuses. Relays act as a switching device, which gives a signal to the circuit breaker as soon as a fault in power distribution is logged.

Ground-faults are by their nature harder to detect, as the current tends to drop rather than surge, like in overcurrent protection. They are particularly difficult to locate in arcing ground faults, where the break in insulation creates an arc of electricity from the circuit to the control panel frame or body.

Generally speaking, the aim with ground-fault protection is to firstly protect the user, and then to protect the equipment within the control panel or the building. Ground-fault circuit interrupters (GFCIs) should be implemented into the design and build, acting as a circuit breaker during line-to-ground faults. This provides automatic protection against electric shock from accidental grounding, both for the user and sensitive internal components.

Speak with the DualTEC team for more information on integrating circuit protection into your control panel

This article aimed to provide a guide of which essential elements of circuit protection should be integrated into modern control panels. Whilst we have simplified the process in this overview, DualTEC’s team of electrical engineers has a wealth of knowledge and experience that can be applied to all manner of projects and industries, however simple or complicated. If you would like more information on our control panel design and building service, don’t hesitate to get in touch with us on 01535 609314 or email info@dualtec.co.uk.