GENERATORS IN HOSPITALS
Certainly for an installation of this type, total or partial loss of electrical power can cause major problems in medical tasks and surgical procedures, diagnostic tests failures, failures in life support machines, etc. So that the installation of systems of backup of the electrical system, as they are the generators become vital importance.
In an installation of a hospital, two are the most important criteria, security of supply and security of use of electric power.
The complexity of this type of facility requires a thorough preliminary study, carried out by specialized technicians, to dimension and design the electrical distribution system of the hospital.
Let’s see how the generator sets fit into a system as complex as the one required by hospital centers.
REGULATIONS APPLICABLE TO THE INSTALLATION
The regulation applicable to this type of installations will vary according to the country in which it takes place. Based on the Spanish regulations, regulated by the Electrotechnical Regulation for Low Voltage, (REBT), which typifies the hospitals as public public places, so they must have at least two types of electricity supply according to ITC-BT -28:
- A normal supply (SN) according to the forecast of loads that in the hospital are estimated. This normal supply is usually supplied by a supplier.
- A complementary supply (SC), which in the case of a hospital must be a reserve supply, defined in art. 10 of the REBT, dedicated to maintaining a restricted service of the essential operating elements of the installation, with a minimum power of 25% of the total power contracted.
In addition, the ITC-BT-38 establishes the need for a special supplementary supply (SEC), Batteries or similar, to meet the requirements of the operating room lamp or intervention room and life support equipment, must enter automatic mode in less than 0.5 seconds and has a range of not less than 2 hours.
For this type of installations it is advisable to include, if possible, a series of measures that are detailed below, which are not mandatory, but greatly improve the installation.
- The normal supply (SN) will be made from the AT / MT network through a double connection of independent lines and, if possible, with power guarantee in both lines.
- The operation of the hospital in island mode must be ensured through the provision of energy, certain charges judged to be essential for safety, patient care and the effective operation of the hospital through its own means of production (mainly through Generators). This must be at least 50% of the total power contracted for normal supply.
- Extend special supplementary supply (SEC) to other loads considered critical for the proper functioning of the hospital, not included in ITC-BT-38, guaranteeing service without cutting.
- For safety reasons in situations of maximum emergency and / or catastrophe, provision should be made for the necessary infrastructure to permit the use of one or more external distress sources such as mobile generators.
POWER SUPPLY SYSTEM
The supply of the normal supply should be done from the public network, using whenever possible, a redundant design of the electrical network connection to the hospital, using two external lines, actually separated, ie fed from substations and / or transformers and Independent paths.
Given the tendency of dispersion of structures in the design of hospitals, it is advisable that the double network connection be designed with ring type and radial exploitation. That is to say, it contemplates the possibility of double alternative ways electrical supply between the different structures, avoiding in their plotting and installation possible common mode faults.
Given the impossibility of guaranteeing 100% continuity of electricity supply, only with the two external power lines. The complementary supply must be guaranteed by means of production, usually thanks to generators.
For safety and with the intention of improving the operating performance of the groups, the generation of this complementary supply will be carried out centrally with generators in parallel with switching. In this way, both the SN and the SC will supply the different CGBTs (General Low Voltage Charts) through the same network.
The control of the groups must allow the programming of the startup of the same when a power failure is detected through the main line. However, the connection to the network must be timed and carried out only when the transfer from the external connection to the backup line also fails (If it exists).
In the case of centralized generation with parallel groups, adequate control mechanisms must be provided so that the connection / disconnection of each of the groups to the network can be carried out independently and depending on the connected load.
The control must incorporate equipment that guarantees the synchronism of the groups and the suitable interlocks so that, in a manual or automatic maneuver, it prevents the coupling if the synchronism has not been realized.
These generators, in addition to complying with the service characteristics required by ISO 8528 to emergency groups, must be able to cover 100% of the hospital’s essential load needs in a stable and continuous manner. To this end, each group must have its own fuel tank that guarantees its operation for at least 24 consecutive hours; And an outer tank with sufficient capacity to ensure the supply of fuel must be provided for at least 8 days.
The control equipment of the groups must incorporate, as a provision, the possibility of performing load transfer maneuvers without cutting between the generating set and the network, in such a way as to allow:
- The return, without cut (without passage through zero), to the normal operation scheme after a failure of the external power and replacement of this one.
- Performing maintenance operations connections and disconnections actual load without cutting.
- Performing charge transfer operation without cutting at peak times, if applicable.
- Automatic synchronization equipment must be available to allow the connection to the network for a maximum of 5 seconds.
- They should be included in the side of MT generators, protection systems maximum and minimum voltage, frequency, overload and short circuit currents.
In addition, protection systems should be included to avoid sending energy from the groups to the network.
This is roughly the main features of an a facility in a hospital. Although as indicated at the beginning of the article, each project must be studied in advance by a specialized technical team to assess the specific peculiarities in each situation.
This type of facility carries a great responsibility, so the equipment installed in this sector are high-end, which guarantee maximum performance and durability, since a failure in the emergency system could mean, in the worst case Cases, human losses.
DO YOU WANT TO INCORPORATE A GENERATOR SET INTO YOUR ELECTRICAL SYSTEM?
In Tecnics Grupos Electrógenos, S. L. we have a highly specialized technical team, which has a wide experience in the sector.