Comment

Power is nothing without Protection and Control

Engineering consultancy Frazer-Nash has been working with Network Rail to construct a safety case for the development and subsequent roll-out of Integrated Protection and Control (IPC), an important component of the electrification of main routes nationally. Richard Jones, rail business manager at Frazer-Nash, outlines the benefits of IPC.

The expansion of the electrified network provides an ideal opportunity to implement modern protection and control methods in place of the traditional complex array of hard-wired switchgear control circuits. The Network Rail Integrated Protection and Control (IPC) project is taking a novel approach to replacing the hard-wired control circuits by integrating a modern communications network with Intelligent Electronic Devices (IEDs) and Remote Terminal Units (RTUs). 

IEDs use programmable logic to describe the electrical functions needed rather than hardwired control circuits and consequently reduce installation costs. With this arrangement, information can be communicated between IEDs, providing greater flexibility and functionality of the protection and control schemes. Control and monitoring of the IEDs is achieved via an interface with the RTU and SCADA network back to the Electrical Control Room and its operators. 

What is IPC?

Electrified routes on the rail network rely on complex hard-wired circuit breaker protection systems to control the traction current to trains. On overhead electrical lines, these circuit breakers distribute voltages of 25KV with fault currents up to 12KA – a significant amount of instantaneous energy. 

Protection systems have complex hard-wired connections that are interconnected in marshalling cabinets in substations, but the amount of information that can be passed through the system is limited. Installing and maintaining this system is time consuming, expensive and can only be carried out by those with highly specialised training and experience. 

Implementing IPC means substituting marshalling cabinets and complex wiring for a modern network-based system. This allows more information to be communicated more quickly and so offers a major improvement on the protection schemes currently in place. The IPC system detects fault conditions more quickly and switches breakers out much faster in fault conditions. 

Benefits 

A big advantage of this new system is its ability to implement improved electrical protection schemes, notably Accelerated Distance Protection (ADP) and Rationalised Auto Transformer System (RATS). Both of these protection schemes make use of the new data network. 

Under Accelerated Distance Protection (ADP), an electrical fault, for example a short circuit, can be cleared in a faster time than under existing Distance Protection. 

This is achieved by the IED that detects the short circuit, communicating across the data network to other IEDs in a faster time than existing Distance Protection. This improved, accelerated, distance protection reduces the amount of costly damage that can occur to equipment under fault conditions.

The Rationalised Auto Transformer System (RATS) allows for the reduction in the number of costly circuit breakers whilst maintaining a fully protected electrification network. With each circuit breaker costing up to £40,000, there is the potential for worthwhile savings in these large schemes. Additionally, as circuit breakers require a location building, fewer breakers means further savings for the industry. In relation to maintenance, IPC/RATS offer significant savings, with less complex location wiring and better information available for remote diagnosis and reconfiguration activities. Overall reliability is expected to be better and repair times shorter as a result. 

All of these changes to equipment, maintenance and operating procedures raise the question of safety for both railway workers and rail users. We have been working with Network Rail to develop safety cases for both the National Programme of IPC development and subsequently for several of the regional roll-outs.

Not only is Frazer-Nash accredited for rail safety engineering under Link-Up but also has experience of IPC schemes in other industries. Much of the company’s work is in innovative areas where their cross-industry approach can bring the necessary knowledge to bear on a problem very quickly and with good results. 

This is a time of huge change and record investment for the rail industry, and with the electrification of major routes, presents a genuine opportunity to embrace new engineering solutions. 

IPC represents just one example of a technology that can improve the reliability of the UK’s rail industry, and at a significantly lower installation and operation cost to Network Rail than ever before.