Maintenance is just as crucial for standby power systems as for those that run 24/7. Peter Purdy offers top tips for both the selection and ongoing maintenance of a backup power system.
According to the Royal Academy of Engineering, the UK would face ‘severe economic consequences’ if there was a serious disruption to the electricity supply – with costs running into billions of pounds. Analyses from insurance company Allianz on blackout events in the US show that a 30-minute power cut results in an average loss of $15,709 for medium and large industrial clients, and nearly $94,000 for an eight-hour interruption. One way to mitigate this risk is to ensure a reliable backup power supply is in place, typically through the use of standby diesel generator sets. However, by virtue of the fact that such systems are commissioned on a standby basis and will only come online in the event of an emergency, they are not in regular use and therefore may not be subject to the same stringent maintenance regimes as other capital plant.
To ensure that, in the event of an outage, power can be available instantly, operators need to specify their generator installation carefully. There are some basic considerations that any equipment supplier should be able to meet with relative ease. These include considering the generator footprint and the space available as well as any noise level specifications set by local authorities or standards bodies.
|Fluid and condition monitoring can result in a 10-fold return on investment in backup power systems
Credit: Finning Power Systems
The system should be designed around the site load requirements including critical power demands as well as any general power needs. The correct load profile can then be calculated, which will ensure the generator is specified to handle any in-rush currents without affecting the operation of downstream systems.
Above all, each generator set should be sized correctly according to the demand for power should grid electricity become unavailable. As a failsafe measure, some operators may opt for generator sets rated for prime or continuous operation with unrestricted running hours.
While this provides the necessary assurances of power continuity, it can also be a costly approach. Not only is equipment specified with a higher rating than necessary under normal operating conditions, it can result in the installation of larger units that take up more space and may require more frequent servicing and maintenance.
As a result, engine suppliers are engineering systems that offer a higher maximum expected usage, with varying load for the duration of the outage. This means that operators can benefit from a smaller, more compact generator set that is sized closer to the load, and still retain the same power resilience available from a larger unit rated for continuous operation.
Monitor fuel quality
In most applications, backup generators will only operate occasionally, which means that the fuel required to run those sets could have been stored for many weeks, months or even years.
During this time the diesel fuel supply can become contaminated which can cause serious damage to the generator’s internal components – potentially affecting the engine’s performance and, at worst, its ability to start up in the event of a power failure. These contaminants can include dust, rust, algae or water and can lead to operational problems including filter blockage and the premature wear of systems such as injectors and fuel pumps.
No operator wants to throw away fuel unnecessarily. With current red diesel fuel prices at £0.95 ($1.47) per litre, based on a 1000 litre tank, operators could be faced with a refuel bill of almost £2000, in terms of both the dirty fuel lost (£950) and the expense of the new, replacement diesel (£950). In addition, with environmental concerns high on the agenda for every processing plant, the cost and potential hazards of oil disposal are to be avoided at all costs.
|Fluid analysis can show the quality of diesel fuel that may have been stored for many months Credit: Finning Power Systems|
This is where investing in a fuel advisory and monitoring service can pay dividends. Carrying out routine sampling and analysis can help to identify any potential degradation of the fuel before it results in costly downtime. The vast majority of contaminants can then be removed and the fuel cleaned and reused. Finning, for example, offers a comprehensive fuel polishing and biocide treatment service, which is available from approximately £500 – around half the price of replacing the dirty fuel.
This predictive approach to fuel maintenance can also extend to the working components of the generator set itself. Regularly sampling the oils, fluids and coolants will help to deliver the performance insight that operators need together with recommendations for action to ensure generator set reliability.
What is fluid analysis?
Put simply, fluid analysis is the process of extracting a small amount of fluid from an engine compartment, which is then sent away to be analysed. Fluids are removed from the working parts of the engine, including oil, fuel and coolant. The extraction of the fluid is a simple process and can be carried out by the operator without the need for a service engineer.
The fluid sampling kit includes a length of tubing that can be cut to size and simply ‘plugged’ into the specific engine compartment with the sample pot and a vacuum pump attached to the other end. Taking space limitations into account, this simple process is both swift and efficient. The samples can then be sent back to Finning’s team of professional diagnosticians, who will carry out a series of element tests and interpret the results.
Oil: the lifeblood of any machine
Conducted at its state-of-the-art laboratory, Finning’s oil sampling service tests for metal and water contamination, abrasive wear, viscosity, acidity and cleanliness. This not only allows remaining product life to be accurately predicted, but also enables any changes in component condition to be identified.
Failure of electric power distribution due to the condition of transformer oil could compromise safety and will inevitably result in high repair costs and extended downtime. This managed service from Finning covers the supply of the oil sample kits, together with return postage and includes full analysis, reporting and trending. A typical sample turnaround is just 48 hours.
Customers using Finning’s fluid and condition monitoring service on a regular basis can achieve around a ten-fold return on investment. This return will depend on the environment and application but demonstrates that the cost of sampling is minimal in comparison to major repair or component replacement.
Analysis in action
As soon as a fluid sample has been analysed and the report compiled, Finning will email the results back to the customer directly and post them on its online reporting system, Infotrak. Infotrak allows customers to view up-to-the-minute information and historical data – at any time of the day or night, from anywhere in the world. Some of the key features of Infotrak include a traffic light system that allows the customer to see at-a-glance which samples require attention, along with full history and graphing, highlighting trends on a particular machine or compartment, or across an entire fleet.
Optimisation of the fluid lifecycle through careful monitoring and the implementation of a contamination control system ensure the system remains clean. The benefits of fluid analysis go beyond the reassurance of a well-performing, reliable engine. By cutting the risk of major repair, breakdown and engine failure, fluid sampling offers a solution for providing consistent performance and peace of mind.
Any capital investment needs to be carefully considered. Aside from the purchase cost, purchasing teams will also want to ensure their equipment investment offers low cost of ownership.
While backup generators may operate for 30,000 hours or more between major overhauls, even the best system needs to be maintained on a regular basis to make sure it operates properly when needed.
Many operators are considering the benefits of remote monitoring as a means of ensuring round-the-clock support for their mission critical equipment. Montoring 24/7 via ethernet/cell or phone line, engineers can identify any faults and predict potential downtime, including accessing pre-settings and parameters on the generator to assist site engineers. An engineer can then be dispatched to site to carry out any remedial work or, alternatively, onsite facilities’ engineers can be texted to alert them of any alarm faults.
Case study: standby power for Guy’s Hospital
At Guy’s Hospital in London, UK, Finning has been appointed to deliver the new 11 kV emergency electrical services standby generator system.
Part of Guy’s and St Thomas’ NHS Foundation Trust, the hospital is upgrading its old standby generator system to meet current and future demands for continuous power to sustain its worldwide recognition in the delivery of medical care.
In a hospital environment, standby power infrastructure is not just essential; it could mean the difference between life and death. Therefore, continuity of power is business critical. As part of the project, Finning is providing three Cat C175-20 generator sets, each providing an output of 3200 ekW, the highest output available from a single high-speed generator set in the UK market. Once installed, these units will provide a combined 9600 ekW of reliable, mission critical standby power.
Guy’s Hospital is currently building a new, state-of-the-art Cancer Centre, which will be a hub for South East London, providing specialist cancer services, training, development and research. The new centre will enable Guy’s and St Thomas’ NHS Foundation Trust to improve its cancer treatments and outcomes when it opens to patients in 2016.
As part of the ongoing upgrades, the hospital is increasing its electrical standby power capacity. Working with Eta Projects Ltd, the Trust’s specialist power engineering consultants, Finning is supplying a generator system that will provide 100% of the standby power requirement to the Cancer Centre in the event of a mains power failure. In the event of a mains power failure across the entire hospital, the generator sets will provide approximately 80% of the standby power.
David Porter, Head of Compliance at Guy’s and St Thomas’ NHS Foundation Trust, said: ‘The process to upgrade the electrical standby power capacity at Guy’s Hospital began in early 2014. In consultation with Eta Projects Ltd, a detailed tender was published through the Official Journal of the European Union. Due to the spatial constraints, we considered three different sizes of engines and appointed Finning, which offered the C175-20, because of its compact size and high power output. The small footprint of the C175-20 means that the new units can be housed within the existing generator rooms without any major building modifications.
‘The generators are interconnected to the main 11,000 V electrical intake substation for the hospital through a dedicated generator distribution switchboard. The generator sets will be linked to the hospital’s existing logic control systems to ensure that standby power is readily available and appropriately prioritised within just 15 seconds in the event of an outage.’
The generators are designed to operate in synchronous parallel mode and as single systems through manual intervention by the Hospital Estates Engineering team should the need arise.
Prior to delivery to site, the new generators were subjected to intensive factory testing which included load bank testing for four hours at 100% load and a subsequent one-hour test at 110% load. In addition, transient load tests were applied at various step loads from 60% to 100%. As added value and to demonstrate confidence in the generators, the test engineers applied a single load step at 110% and the generators took the load without stalling.
The first generator has been delivered and placed in situ, with final works underway to integrate it into the hospital’s electrical system. The final installation of the three C175-20 generator sets was completed in March 2015.
Peter Purdy is Power Generation Product Support Sales Manager at Finning Power Systems