Power distribution in a challenging continent

Louise Davis

The llama, anaconda, anteater and chinchilla are just some of the 40% of the world’s plant and animal species native to South America. This diversity is due to the continent’s unique geography, which has widespread effects on every aspect of life. The South American geography and climate also has a considerable effect on the resistor market.

Often known as the continent of extremes, South America is home to both the world’s greatest river and the driest desert. Its geographic variations include the snow-capped Andes, tropical jungle, savannah-style grasslands, the mighty Amazon and Orinoco river deltas and coastal plains. This extreme geography has resulted in the formation of isolated communities, which means that power distribution can be piecemeal in nature, a notable difference from the National Grid of the UK and the Synchronous Grid of Continental Europe.

Remote conditions
The power needs of communities and remote locations can have a number of indirect effects on the resistor market. Geographical constraints on electrical distribution have resulted in a de facto reliance on localised generation and battery technology in some places. Localised generation systems, which often consist of several generators, are usually isolated from the grid network.

In the event of an earth fault, resistors can be used to limit the flow of current and thereby the risk of damage to generators and other equipment. However, where multiple generators are connected in parallel to avoid circulating earth currents, only one generator should be earthed. One way of ensuring this is to use a single earthing resistor with multiple vacuum contactors.

It is essential that back-up battery systems work properly when called into action. Portable load units can be used to test the capacity of standby batteries and the output of generators by simulating the working load.

As standby systems are often installed at remote locations, test equipment must be easily transportable. Because Cressall’s load units were originally developed for use in the field by telecoms, rail and offshore companies, they are easy to handle and can be operated by one person.

Climate considerations
From the hot and wet climate of the Amazon basin through to the snow-capped Andes and the deserts of Chile, Peru and Venezuela, the continent’s climate varies greatly in accordance with its geography, ocean currents and winds. These challenging environments demonstrate the importance of equipment being designed appropriately, with respect to mechanical, electrical and environmental positions. Enclosures must be used to protect contents from external elements, including wind, rain and sea mist, yet allow sufficient ventilation to dissipate the heat generated during operation.

To achieve trouble-free operation, engineers must ensure enclosures are designed to avoid high levels of humidity and contamination as these can reduce insulation resistance.

Using non-hygroscopic materials and correct insulation design mitigates against the build-up of pollution, which will ensure the long and safe working life of equipment.

Natural disasters are relatively common in Latin America. This means that equipment needs to be resilient to earthquake tremors.

Originally developed for use in rail traction and on board ships, Cressall’s resistors are robust and can be designed to withstand high levels of shock and vibration. Where specific seismic criteria need to be met, finite element analysis tools are used to ensure suitability.

Wind power
With Latin America expected to commission more than 47GW of new wind power capability between 2017 and 2026, this particular renewable source is a popular choice. With a relatively low population density and energy needs in remote areas, Brazil, Chile, Peru and Columbia offer an ideal scenario to harness wind energy.

Multiple types of resistor are used in wind power generation, including pre-insertion resistors (PIRs), dynamic braking resistors (DBRs) and crowbar resistors.  PIRs limit the in-rush current into transformers when the system is switched on. DBRs control the over-speeding of turbines from gusting winds, and crowbar resistors can prevent damage to the power electronics of the turbine by short-circuiting the rotor windings in the event of a grid disturbance.

Larger installations, such as offshore wind farms use large damping resistors in complex static VAR compensator (SVC) networks. These resistors help stabilise fluctuating voltages brought about by changing wind speeds.

Scattered communities
Although the region’s scattered communities pose challenges to power distribution in South America, scattered international business communities present a whole new set of problems.

Mainland South America is split across three time zones, ranging from GMT-3 in eastern Brazil and Argentina, GMT-4 in Chile and Western Brazil and GMT-5 in Peru and Colombia.

With the potential for up to a six-hour time difference between a local buyer seeking support from an international resistor manufacturer, there can be many difficulties for South American engineers. This is why it is important to choose a manufacturer with a support team that is experienced in communication with customers several time zones away.

Cressall is familiar with working across a global market and its multilingual team is familiar with working in foreign languages when necessary. Other perceived problems, such as logistical coordination, are not an issue for the company as it is used to exporting on a global basis.

Wherever possible, Cressall works with local distributors and representatives, to ensure its customers receive the same standard of service regardless of whether they’re based in Spain, Saudi Arabia or Sweden.  

The continent of extremes has unique climates and challenging geography with a continuous demand for industrial resistors. From renewable energy to ensuring the reliability of back-up power systems, operators and engineers must ensure their resistor manufacturer is familiar with the continent and its challenges.

Stewart Wittering is with Cressall Resistors. www.cressall.com


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