Cape-based Hidro-Tech Systems offers turnkey liquid transfer solutions in the Cape’s hotly contested field of water and wastewater projects.
The company focus is on water supply projects, waste-water pumping stations, and water and wastewater treatment plants, for which it bids against specifications drawn up by consulting engineers. Successful tenders are followed by equipment procurement, installation, testing and commissioning. Life-cycle maintenance services are also offered.
Preferred partner
Following successful Moeller switchboard performance on Hidro-Tech’s Western Cape projects the company has appointed Moeller its preferred partner for electrical equipment.
Through this relationship Moeller has provided Hidro-Tech with switchboards for the Rooidraai irrigation system, for Bonnievale wastewater treatment works, for the potable water supply to Groot and Klein Mier in the Kalahari, and for the Serengeti Estate sewage pumping system.
Bonnievale
The Bonnievale installation provides insight into the cutting-edge technology incorporated in South Africa’s newest wastewater treatment works. For this project, Moeller worked closely with local panel-builders on the engineering, system integration and manufacture of the motor control centre (MCC) housing all starters and control equipment for the wastewater treatment works.
A modular board was used to form the basis of a system designed for a 15 kA fault level. The board comprised an 800 A Moeller main incomer, busbars, metering and surge protection. The various starter compartments housed control and switchgear for the vertical shaft aerator soft-starters, for the vertical shaft mixers, liquor recycle pumps, rotating bridge clarifiers, waste-activated sludge pumps, final effluent pumps, forward-and-reverse mechanical screen, and for the chlorine booster pump.
All direct on-line starters were designed to type-2 coordination using the Moeller X-Start contactors and PKZ2 motor protective circuit-breakers with removable trip blocks. RMQ Titan pushbuttons and indicator lamps were used to manage the start-stop function.
To ensure equal pump operating times and minimise maintenance requirements the control design for the pump sets included an alternating duty system with dual redundancy on each pump set. During a fault, the dual redundancy control automatically forwards the duty to the available pump set, thus avoiding interruption of wastewater treatment.
For the mechanical screen Moeller designed a 1,1 kW forward/reverse starter. This included an Easy 800 for variable cycle control of the screen in automatic operation. Revolution counts and torque measurement determine the forward and reverse operations. When an over-torque situation is detected the screen direction is changed automatically.
System control was managed by an Easy 800 programmable relay (programmed by Cybernetics). This greatly reduced the design and manufacturing times by simplifying the relay logic within the panel. This also improved on space saving within the panel by replacing necessary control equipment such as timers, counters and comparators.
Hidro-Tech and Moeller are presently tendering on further water supply and sewage pump stations as well as water and wastewater treatment projects in the Western, Eastern and Northern Cape provinces.
For more information contact José Ruivo, CBI-electric Low Voltage, +27 (0)11 977 0700, [email protected], www.moeller.co.za
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