Who says water and electricity don’t mix?

Access to water resources for all uses rests on electricity

By Morand Fachot

Poor water quality and water scarcity continue to pose a major threat to human health and are responsible for millions of deaths every year. Extracting water and treating used and contaminated waters requires complex installations which depend almost entirely on electrical and electronic systems and equipment. Standardization work by many IEC Technical Committees (TCs) and Subcommittees (SCs) is essential to ensure that people across the world have access to appropriate water supply and water treatment. 

Cutaway of a UV water sanitation unit (Photo Delta UV)

No electricity, no pumps, no water

Having access to clean and safe water is vital. Pumps are the basic piece of equipment used to extract fresh water from sources, to bring it to users and to move and treat wastewater.

Electricity is now the primary and the only practical source of energy for individual pumps and for pumping stations that supply water to towns and networks.

Pumps are built around rotating machinery. IEC TC 2 prepares International Standards for motors used in pumps.

The pumping of fresh water and wastewater is said to account for 10% of the world’s energy usage. Employing energy-efficient pumps is thus essential to keep in check electricity consumption. IEC TC 2 has developed publications that cover methods of and tests for determining the efficiency of motors. The efficiency of three-phase, single-phase and synchronous motors is the object of a classification given in IEC 60034-30-1: 2014, Rotating electrical machines – Part 30-1: Efficiency classes of line operated AC motors (IE code). The least efficient motors are classified IE1, the most efficient IE4.

Many companies that supply motors for fresh and wastewater pumps stress that they meet IEC high-efficiency ratings. 

Renewable energies – a perfect match for complementing water supply

Solar-powered pumps are used where grid electricity is not available. They generally use photovoltaic (PV) panels. IEC TC 82: Solar photovoltaic energy systems, develops International Standards for various components and systems used in PV installations, such as controllers needed for voltage protection or the converters and inverters that are necessary when DC supplied by PV panels has to be converted to AC for certain pumps.

There is growing water scarcity in many parts of the world and “seawater desalination is the only additional renewable source of freshwater available on this planet”, according to Global Water Intelligence. Desalination is now used in 150 countries; it is a highly energy-intensive process. In many countries – in particular oil-rich countries – most desalination projects rely on energy from fossil fuels (oil and gas) to operate.

However, various sources of renewable energy (RE) now offer interesting prospects for clean energy desalination and several desalination projects using RE are being developed. Spain’s Abengoa RE company will build a 15 MW solar PV facility for a desalination plant to supply Al Khafji City in the north-east of Saudi Arabia, it will produce 60 000 cubic metres of water a day. It is due to be commissioned in early 2017.

In Australia, the Perth Wave Energy Project has the ability to produce desalinated water using wave energy. IEC TC 114: Marine energy - Wave, tidal and other water current converters, prepares International Standards for these types of installations.

Wastewater treatment/purification

Wastewater (from domestic, industrial and other uses) treatment is a multiple-stage process that includes mechanical and chemical phases. All require electrical and electronic equipment.

Wastewater is sent first for treatment to clarifier tanks where rotating arms, relying on rotating machinery, skim off oils and fats. Chemicals are used in sedimentation tanks where they are added to wastewater to aggregate solid particles, which fall to the bottom of the tanks to be collected and recycled in various forms. For this process, chemicals must be added in the right proportions. This is made possible using digital dosing pumps, which can be microprocessor-controlled.

Water can also go through an ultraviolet (UV) sanitizer unit to kill pathogens, germs and viruses, and reduce significantly the quantity of chemicals, such as chlorine and bromine, needed to disinfect water.

IEC TC 61: Safety of household and similar electrical appliances, has developed IEC 60335-2-109:2013, an International Standard for Particular requirements for UV radiation water treatment appliances. UV radiation treatment is important when water needs to be further processed to be potable, or for use in water recreational areas, in which case digital dosing pumps may again be essential to add certain chemicals in smaller volumes.

Saving water in homes and public spaces

Water is seen increasingly as a scarce resource that cannot be wasted. In homes and public places with conveniences, like restaurants, hotels, shopping centres and sporting installations, sensors are increasingly used to flush toilets or to get running water from taps automatically.

This is made possible through the work of IEC SC 121A: Low-voltage switchgear and controlgear, which has developed an International Standard, IEC 60947-5-2:2012, Control circuit devices and switching elements – Proximity switches, which covers these sensing means: inductive, capacitive, ultrasonic, diffuse reflective, photoelectric, non-mechanical, magnetic, retroreflective, photoelectric and through beam photoelectric.

IEC Standards apply to recreational use of water too

Recreational use of water, in swimming pools and spas, for instance, requires its own Standards. Some cover equipment and systems previously mentioned, others, such as certain safety requirements, are specific to the recreational environment.

A clean and comfortable setting is important in public and private swimming pools and spas. 

Pool equipment and maintenance systems include a variety of devices for heating, cleaning, sweeping, pumping and lighting. They include automated systems, controllers and safety equipment. Most rely on electricity, but water and electricity have an uneasy relationship.

As safety is always at risk when water and electricity are in close proximity, in particular when individuals are around, the design and installation of such equipment and systems must meet strict criteria to protect against electric shock.

These criteria apply to electrical installations for swimming and paddling pools and their surrounding zones, and for basins and fountains as well as “areas in natural waters, lakes (…) specially intended to be occupied by persons for swimming, paddling and similar purposes”.

IEC TC 64: Electrical installations and protection against electric shock, developed IEC 60364-7-702:2010, Requirements for special installations or locations – Swimming pools and fountains. This Standard defines the dimensions of three zones in which such equipment may be installed and stipulates what may go where¸ as well as the characteristics of wiring and current-based equipment used in swimming pools.

Several IEC TCs and their SCs prepare International Standards for these electrical installations. They include TC 61: Safety of household and similar electrical appliances, and SC 34D: Luminaires.

Clean and clear

Cleaning of pools is essential for health reasons and to avoid contamination. It relies on mechanical and chemical processes which are all controlled by electrical systems.

Cleaning involves constant recycling by removing debris (i.e. hair) and dirt – such as creams or cosmetics – from water before sanitizing it.

The first stage is pumping water from the bottom of the pool or from the sides when it overflows into channels. Next it is sent to sand filters, which are large tanks filled with sand that trap dirt and small particles in the 20-100 micron range.

Following this first treatment, water goes through a UV sanitizer, similar to the ones used in wastewater treatment, which reduces significantly the quantity of chemicals – such as chlorine and bromine – needed to disinfect water. Some manufacturers claim that “savings of 70-85% in chlorine consumption are commonplace” when a UV sanitizer system is installed.

However, even after UV treatment, chemicals such as chlorine still need adding to make certain water is not contaminated. This is done using digitally-controlled dosing pumps that ensure the right amount of chemical is continuously injected into the water before it is pumped back into the pool. 

Pleasant environment

Lighting can enhance swimming pool and spa environments and overall user experience. Lighting fixtures may be installed outside the pool, above ground or recessed, and underwater in appropriate housings. Light can be delivered via a variety of bulbs, LEDs or fibre optics.

IEC SC 34D: Luminaires, has published IEC 60598-2-18:1993, Luminaires – Particular requirements – Luminaires for swimming pools and similar applications. This International Standard details general test requirements, the classification of luminaires and characteristics of their construction. It also describes tests for mechanical strength and corrosion and many other features for light fittings that are used in the swimming pool environment.

Evacuating excess humidity from all areas in a swimming pool, from shower rooms to the main swimming hall and other areas, and maintaining the right temperature all year long make for a more pleasant environment. This requires extensive ventilation installations. IEC SC 61D: Appliances for air-conditioning for household and similar purposes, prepares International Standards for electrical air conditioners and dehumidifiers used in residential, commercial, industrial and other buildings.

The strongly-held belief that water and electricity don’t mix really doesn’t hold… water! Nowadays, there wouldn’t be water for personal, industrial, farming or recreational use without electricity or the right electrical systems and equipment. These are entirely dependent on IEC International Standards to function properly and safely. 

pv_battery_gabon Solar PV panels covering battery cabinet in Gabon. Equipment like this is used in off-grid locations to power pumps and other systems (Photo: Meagle Sun)
uv_system-2 Cutaway of a UV water sanitation unit (Photo Delta UV)
enclosures Electrical enclosures that control all operations in a swimming pool
Chemical_pumps_at_water_purification_plant Digitally-controlled dosing pumps ensure the right amount of chemicals is added to water at the water purification plant before distribution (Photo: Z22, Wikimedia Commons)