Can you bank on your back-up power?

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    How do you know your back-up power will kick in when it is needed? A recent report suggests there is unrealistic optimism about resilience. Paul Brickman of Crestchic examines why critical sites should consider investment in loadbanks as part of their strategy to ensure uptime 

    With recent research from Centrica stating that 33% of energy decision-makers believe their organisation is not prepared for a disruption to their energy supply from a temporary grid failure, there are calls for more attention to be paid to the role loadbanks play in energy resilience strategies.

    The Centrica report predominantly highlighted the disparity between the threat posed by energy-related failures and the priority that businesses give to having a strategy for a response in place. Loadbanks are a simple and effective solution. 

    While most businesses understand the importance of having a robust back-up generator in place, they do not consider what would happen if the back-up generator didn’t meet the critical loads it is supposed to, when called upon. That is where loadbanks come in – they are the unsung heroes of energy back-up.

     Loadbanks develop an electrical load which is then applied to an electrical power source that can effectively simulate power failure under full load demand, thereby ensuring that all generators, controls and switch panels function as required in real conditions. 

    There is certainly unrealistic optimism when it comes to energy resilience. The headline finding from the Centrica report says that businesses are risking £2.8m of annual revenue through lack of energy resilience, so why is there such a high percentage of businesses with no plan in place? People often think it will not happen to them. It may come as a surprise to many but it is much more likely that an outage will occur now than 20 years ago. This is because there is less of a buffer of power available nowadays.

    As highlighted by National Grid’s recent report on frequency response reserve, the amount of system inertia has been reducing in recent years, which results in the system frequency becoming more volatile closer to real-time and, therefore, susceptible to potential brownouts. As the Centrica report states, this is due to the replacement of steady ‘base-load’ generation methods with more sustainable, renewable energy sources.

    National Grid’s report outlines its existing Enhanced Frequency Response (EFR) product will improve operation of the system, but in its current form is not necessarily the optimum design of a fast-acting product. While decreased system inertia is high on the agenda of National Grid, there is not yet a robust solution in place, making it even more crucial that businesses implement further measures to protect their power systems.

    Given that the cost of a loadbank is typically only a fraction of that of the systems which it supports, it makes sound commercial sense.

    Paul Brickman, Crestchic

    There are some questions that we are frequently asked about loadbanks and this article will seek to address some of these:

    Is it sufficient to just have a generator/UPS for backup power for mission critical facilities?

    A loadbank should always be considered if you wish to safeguard the reliability of standby power systems. If you have invested in any form of uninterruptible power supply and/or diesel generator, then you will find that the cost of a loadbank is considerably lower. It is imperative you use the loadbank to test those systems to make sure they work. Any generator that spends its life ‘on standby’ is a potential timebomb, if not regularly tested under load. Simply running the generator to idle a few times a month is detrimental to its ability to perform when called upon. In fact, you’ve just risked your investment in the back-up power, risked your entire business operation and potentially risked lives. This is particularly the case for offshore emergency systems, hospitals power supplies or fire suppression systems that are driven by the emergency power facility. 

    How can the public sector justify a business case for investment in loadbanks? 

    There is a real argument here: you don’t have to invest in loadbanks. Crestchic rents loadbanks, as well as selling them, which provides a certain amount of flexibility for businesses. 

    A loadbank is worth the money invested into it. If you do not test your emergency power system, or if you were to test it in a poor manner (ie no load) you are reducing the value of the asset much quicker. 

    If you look at the bigger picture, renting a loadbank is a relatively modest investment that could help save your business in the long run from disruption and a complete shutdown. 

    A resistive loadbank is fine for testing the engine but when there is a need to test the alternator by the introduction of a lagging power factor, then the operator needs to consider the use of a resistive-reactive loadbank.

    What other benefits can a loadbank offer?

    Battery optimisation is one of the biggest benefits that loadbanks can offer. The loadbank can enable a storage system to participate in both low and high frequency demands, while ensuring the battery remains fully charged. This helps significantly reduce the capital expenditure on the main battery itself. 

    By matching a loadbank with a battery storage device, it allows the battery to remain close to 100% charged and therefore increase frequency response revenue by accepting the full income against the battery’s rated output. In times of high frequency demand, the battery simply accepts the charge for an initial 8-12 seconds until the loadbank takes over indefinitely draining the battery of its charge. 

    How will recent legislation around emissions and generators influence the load bank market?

    The Medium Combustion Plant Directive (MCPD) will see an increase in the need to test generators under load. The directive imposes limits on emissions from mid-sized generators. These emissions include sulphur dioxide, nitrogen oxides and dust from plants with a thermal input of at least 1MW and up to 50MW. 

    For newer plants, the limits will come into effect from 20 December 2018, and for existing plants the limits will apply from 1 January 2025. However, this limit will only apply if they have thermal input of more than 5MW, and from 1 January 2030 if they have thermal input of up to 5MW.

    This means there is an increased responsibility on the operator to state the emissions output more often than they have done in the past. There is an exemption for plants that are used for backup generation, provided they are operated for no more than 50 hours per year. 

    This will be lost if they enter into a capacity or balancing service agreements. The use of a loadbank can provide a load to simulate the conditions the generator will experience when exporting to the grid, or when providing a commercial or industrial site with all its power in island mode. 

    What are some of the most common myths and misunderstandings around loadbanks?

    One of the most frequent is that loadbanks cannot operate in the rain. The construction of a Crestchic loadbank ensures that it is completely weatherproof. Many of the larger units are shipped around the world via shipping containers, so they are open to all elements such as changes in temperature and loading and unloading from ship to carrier. 

    We are also regularly surprised at the amount of people who think they must apply the load manually. They are even more surprised to learn the loadbank can be pre-programmed with various load profiles over a given timescale, leaving them free to monitor the generators’ many parameters, such as temperature, exhaust gases and vibration. 

    Voltage is also misunderstood. A loadbank must be specified to the voltage output of the power source. While the loadbank can accept lower voltage, it won’t take kindly to someone plugging in a much higher voltage. 

    You wouldn’t plug your TV into a 415V three-phase supply, or the 33,000V overhead cables and expect it to work, would you?

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