In the healthcare market, medical imaging equipment such as magnetic resonance imaging (MRI) systems are among the critical assets needing power protection. If a hospital or clinic leaves a MRI or a computed tomography (CT) scan machine unprotected from brief outages or power quality disturbances, there is the potential for costly downtime, patient dissatisfaction, and staff productivity issues.
Hospitals, of course, have good backup generator systems. Some hospitals also enjoy redundant utility grid connections. Hospitals also are generally disciplined about performing monthly tests of backup generators. As a result, they tend to be well protected against longer term outages that may come from the incoming utility source. There may, however, be occasions where power disturbance is internal to the hospital distribution and beyond the point of generator activation. Applying an uninterruptible power supply (UPS) system is the best solution to tackle both utility and internal power quality challenges.
When it comes to medical imaging systems or sensitive equipment in labs, there still needs to be power protection for very short duration events and power quality glitches that could disturb the smooth functioning of diagnostic testing and their on- board electronic records keeping. A very small power glitch on an MRI may cause costly downtime, rescheduling of patients, as well as expensive damage to sensitive electronic components.
UPS equipment can protect against short term outages and power quality threats to medical equipment. UPS not only provides the protective “bridge” for the period of time until a generator system kicks in, but a properly sized and applied Static UPS also provides power conditioning that isolates medical equipment from power disturbances. These disturbances might come in from the utility side or perhaps internal to the hospital’s distribution system. They can even be caused by emergency or temporary shut downs due to maintenance required by existing electrical equipment to which the hospital equipment is connected.
Static UPSs typically utilize sealed batteries to provide DC backup energy source in the majority of applications. This has been the most common type of energy storage used by various vendors for many years.
There are times, however, that hospital facility designers elect to use “flywheel” DC storage systems in place of batteries. This may be due to space limitations or other considerations. It’s important to know more about what is involved with this type of solution.
Flywheel storage systems, while generally higher in initial cost than sealed batteries applied with conventional UPS of equivalent KW ratings, have some characteristics which can make them desirable for some applications in the hospital environment. Here are some points to consider:
- Since healthcare sites typically are confident about longer term power availability from generators, they are primarily concerned about shorter duration events that a Static UPS and flywheel combination can protect against (typically, flywheel back up time is 15-30 seconds at full design load).
- Flywheels typically have a smaller physical footprint than batteries which can make them attractive for tight electrical room spaces (and of course less back up time as noted earlier).
- They are generally considered to require less maintenance and a longer replacement cycle than typical sealed VRLA batteries during the operating life of the system.
- Batteries generally need a temperature controlled environment to preserve their life or performance characteristics (Typically 77 degrees Fahrenheit or cooler); a UPS flywheel combination has a wider operating temperature window and can run at a higher temperature, thus reducing energy costs for cooling.
- In the event that additional back up time is required in the future, there’s flexibility to add standard sealed battery strings to the flywheel and UPS block.
While flywheel storage systems have some positive aspects, there is the need for some caution in choosing a flywheel unit with a UPS. For one thing, the UPS manufacturer needs to qualify the flywheel to make sure it is compatible and performs well with the UPS, and that the combination can meet the transient response required by the load. At Schneider Electric, we thoroughly qualify our UPS and flywheel models.
Second, whether a UPS uses a flywheel or conventional VRLA battery as a storage device, it is important that it is sized to meet the peak loads generated by the medical imaging equipment which needs protection. Schneider Electric works closely with hospital facility engineers to pinpoint what these peak loads are, the sequence of operation, other hospital equipment supported, and the best solution required.
Third, some facilities may elect to run a Static UPS utilizing both a conventional battery and a flywheel storage unit in parallel in certain instances. The flywheel storage unit would protect against short duration events, extending battery life in the conventional UPS. This would be in place to provide an extra measure of protection for longer outages and full transition to generator power. It’s really a matter of being able to support what the customer and designer want, and the requirement for the particular facility, rather than forcing one approach.
In the healthcare market, the reality is that a range of UPS products are needed, from standby UPSs to protect nurses stations or PCs in offices, to single phase or three-phase solutions to back up medical equipment, a server room or network closet. This Secure Power brochure explains the range of power protection needs and UPS solutions that are found in hospitals and healthcare facilities.
To find out more about Schneider Electric’s services and solutions for the healthcare market, you may also visit this Web page.