Modular power protection in industrial applications
ENERTRONIC modular SE, 40 kW module
Modular power protection and conversion technology, particularly in the form of UPSs, has long been used in commercial applications, but take-up in industrial applications has, to date, been relatively slow.
This relatively slow uptake is due, in part, to a limited understanding of the “ilities” (“Availability”, “Reliability”, “Scalability”, “Flexibility” and “Maintainability”) commonly associated with modular technology and how the various “ilities” complement each other.
The fourth of five articles within our 'ility' series focuses on flexibility. We will define this in the context of the increasingly important and popular modular technology and discuss how truly flexible systems allow system designers to design power protection systems capable of adapting to the potentially changing needs of a site and/or its critical load.
In previous articles within this series we have defined modularity and discussed how modular UPS systems can be designed to either maximise system availability or minimise total cost of ownership (TCO). We must now consider how we can design a single system that is flexible enough to have the highest availability or lowest TCO with the ability to switch between the two depending upon the prevailing needs of the site/critical load.
Determination of functional characteristics
At the initial design stage of a power protection system, the designer will prioritise the most important aspects of the required system and will most likely compromise on other design aspects. For example, if the load is considered to be business critical the designer will prioritise availability above TCO.
Such prioritisation is not a problem if the needs of the site and/or critical load are guaranteed to never change over the working life of the system (typically 20-25 years), however, we live in an ever-changing world and such guarantees can rarely be given. The danger, therefore, is that a system that was initially designed to meet one set of site/critical load needs may no longer be suitable if the needs of the site/critical load ever change. If this situation ever occurs it may be an expensive problem to correct.
In an ideal world, a system would be designed with the capability to quickly and easily adapt to the prevailing needs of the site and/or critical load.
Such a system could, for example, be increased or decreased in size (see “scalability” article) to optimise TCO or additional modules could be added to it to introduce parallel redundancy (i.e. N+n) if maximised system availability became a requirement.
Finally, it would allow for power capacity to be relocated from system to system if the needs of the critical load(s) across numerous systems ever needed to change.
With the above “ideal world” we can define “flexibility” as a system’s ability to adapt to the ever-changing needs of the site/critical load. High levels of system flexibility help designers to “future-proof” their design and below we will consider a practical example to see how the inherent flexibility of rack-mounted modular UPS helped to future-proof a system and thereby provided numerous financial and operational benefits to the system operator.
An example of a highly flexible system design
Let us assume that a pharmaceutical company decides to start up an experimental production line that needs 60 kW of UPS power. Because of its experimental nature, the directors of our fictitious company restrict the project’s budget and because it does not have a production line, the UPS system is not “business critical”, making TCO a greater consideration than system availability. To meet this design brief a modular UPS system, “rightsized” to the initial critical load by using two 40 kW modules, is installed (see phase 1).
Assuming that the company’s experimental production line is an initial success, directors want to see how easily production capacity can be increased on the experimental line, adding 50% capacity to the production line. This increases the production line power requirement by 30 kW from 60 kW to 90 kW. This challenge is overcome by simply adding one additional 40 kW module to the modular UPS system (see phase 2) to accommodate the increased load and still meet the initial design brief of lowest TCO.
The directors – who are delighted with the performance of the now larger experimental production line, decide to turn it into a real production line and begin serial production of a new drug. This decision now fundamentally changes the design brief of the power protection system because if a power problem causes the production line to be stopped mid-batch, the entire batch must be scrapped, costing the pharmaceutical company tens of thousands of pounds.
The design brief is now to maximise system availability and an additional 40 kW module is added to the modular UPS (see phase 3) to add parallel redundancy and thereby meet the new design brief of maximum availability.
As a result of increasing sales, the pharmaceutical company opens up a new production facility in a town, which is a 30-minute drive away, and decides to move the new drug’s production line to the new production facility. The drug production line’s modular UPS is only 3 years old and rather than investing in a completely new UPS system the directors decide to relocate it to the new facility. However, the downtime on the production line must be minimised and the time needed to decommission, de-install, physically relocate, re-install and recommission the existing UPS is considered to be too great.
The solution is to install and commission an empty modular UPS cabinet at the new production facility (see phase 4).
When the production line is switched off at the old facility, the four UPS modules are then simply switched off, removed from the original modular UPS cabinet, driven by car to the new production facility, fitted into the new modular UPS cabinet and switched back on (see phase 5). Because the new production facility was only a 30-minute drive away, the whole process took less than 90 minutes in total.
The pharmaceutical company now decides to start up another experimental production line on the original site and this line now needs 30 kW of UPS power.
Again, because of its experimental nature, the directors restrict the project’s budget and because it not a real production line, and therefore not “business critical”, TCO is a greater consideration than system availability.
To meet this design brief a single 40 kW module is fitted into the original modular UPS system cabinet and the whole “experimental production line” cycle starts again (see phase 6).
The above example shows the flexibility of a true modular UPS. In this example, we have seen a simple, cost effective:
- Increase in system capacity
- Conversion from a TCO priority to an availability priority design
- Relocation to new premises
- Reduction in system capacity and conversion back to a TCO priority design
Inbuilt intelligence for true flexibility
The example above needed the pharmaceutical company to make decisions and take physical actions to adapt the system to the changing needs of the site/critical load.
In most cases this is perfectly acceptable, however, there may be occasions when it would be beneficial if the system itself were intelligent enough to make decisions and take automated actions to maximise system availability or minimise TCO.
Of course, such decision-making capability must be user configurable to ensure that the system operator retains ultimate system control, but such inbuilt intelligence will further enhance system flexibility.
Modular systems with modules that have the inbuilt intelligence to be parallel redundant (e.g. N+1) when the size of the load means they can be; or parallel capacity (i.e. N+0) when they need to be, enable automatic, real-time flexibility and ensure that the critical load is always supplied with the highest level of protection possible. This capability automatically maximises system availability.
Reduction of power consumption
Similarly, modular systems with modules that have the inbuilt intelligence to use only the required number of UPS modules necessary to supply power to the critical load by putting “excess” modules into a “sleep mode” enable the system to automatically operate as efficiently as it can whilst ensuring that the critical load continues to receive the required level of protection.
If the critical load increases, a “sleeping” module will automatically be returned to full service and if the critical load decreases further then another module will automatically be sent to “sleep”. This capability automatically optimises system TCO.
With industrial power protection systems having a design life of >20 years, one of the greatest challenges faced by system designers is how to future-proof their design by enabling it to adapt to the potentially changing needs of the site and/or critical load.
Rack-mounted modular UPS systems can be quickly and easily reconfigured to allow the power protection system to adapt to site critical load changes and can prioritise either highest availability or lowest TCO depending upon the prevailing needs of the site/critical load.
Rack-mounted UPS modules with user configurable inbuilt intelligence will automatically further enhance system flexibility without removing ultimate control from the system operator.
The next, and final, article in the “ilities” series will discuss “maintainability” and how selecting the right UPS topology will reduce servicing costs, minimise “local” spare parts holdings and enable rapid “first line” fault rectification, all of which will ultimately maximise system availability and minimise total cost of ownership.