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Solutions: On-site Options for Providing Reliable Power to Health Facility Laboratories

Point-of-use conditioning, generator back-up, an inverter/battery system or an inverter/battery system with a no-contact inverter, or a stand-alone off-grid solar power system are options for providing reliable power to health facility laboratories. These options are discussed here.

Point-of-Use Conditioning

Economical point-of-use conditioning can be provided for individual pieces of equipment. These devices are voltage regulators and UPS systems. To perform both functions properly will generally require two separate pieces of equipment.

Point-of-use UPS systems are recommended for all sensitive equipment. (Photo: Jeff Haeni)

Generator Back-Up

Generators are primarily protection from power intermittency. They should be part of every critical hospital power design. Generators can introduce their own power quality issues in terms of voltage and frequency problems if not properly maintained.

Power quality problems can arise when a generator is abruptly switched off. This can cause voltage and frequency spikes that damage sensitive laboratory equipment. This can be corrected by installing proper switches and training operators to switch off the power supply prior to turning off the generator or by the use of an Automatic Transfer Switch.

Inverter/Battery System

An inverter/battery system performs the function of a UPS system that is designed to power several pieces of equipment for up to several hours. (In comparison, a point-of-use UPS system is generally designed to keep the equipment energized for about 10-20 minutes.)

A standard inverter/battery system is connected to whatever AC grid is available when it is available (i.e. national grid or generator). During this time that input power is available, this power is sent straight through the inverter/battery system to power the loads, and is also used for maintaining a full charge on the battery bank. Therefore, during this time, whatever power quality problems exist in the AC power that is connected, are passed through to the equipment. So, a standard inverter/battery system should not be thought of as protecting lab equipment from power quality problems. This is not an issue if the inverter/battery system is powered with solar/PV – as discussed below.

Larger system-wide UPS systems, like this one at the national laboratory in Haiti, are another option when grid outages are short and/or a back-up generator is available. (Photo: Jeff Haeni)

Inverter/Battery System with No-Contact Inverter

A modification of the standard inverter/battery system includes having one or more inverters (depending on total load) that are not connected to the AC power supply. This means that the power going to the loads fed by these inverters will always come strictly from the batteries and through the inverter – thus being pure power. Grid power is still used to charge the batteries. This is a good solution to areas that have problems with voltage and frequency on the grid. (See wiring diagram for example non-contact inverter setup in Haiti.)

Stand-Alone, Off-Grid Solar Power Systems

While generally not appropriate for large district hospitals that are connected to the grid, an off-grid solar system will provide high quality electricity to laboratory loads, assuming that a pure sine wave inverter is selected. With no connection to a grid or to a generator, the power created from the solar/battery/inverter system will have excellent voltage and frequency characteristics. Of course, the wiring from the inverter to the loads has to be done correctly.