Electricity + Control March 2015

DRIVES, MOTORS + SWITCHGEAR

ROUND UP

New motor protection relay The new Rho-C 7SR17 motor protection relay can be applied to 3-phase induction motors of all sizes.The Rho can be supplied with current and voltage inputs and so can provide full current and voltage protection and metering functionality.When the 7SR17 Rho is utilised with the optional voltage functionality, a comprehensive, integrated protection and metering solution is available to the customer ensuring safe and secure operation of plant. Summary of the relay features:

o Stall/ locked rotor protection o Current unbalance protection o Motor thermal overload o Frequent starting o Undercurrent o Instantaneous overcurrent o Directional earth fault o High impedance o Under/ over voltage o NPS voltage/ phase reversal

o Backspin protection o Power/ Power Factor o Under/over frequency o And more… Enquiries: Blazie Magee.Tel. 0861 966 323 or email blaize.magee@woodbeam.co.za

Underground battery chargers … in no time at all Becker Mining SouthAfrica ’s recently launched IGBT mine traction battery chargers have been designed to charge underground traction batteries in the shortest possible time, at the lowest possible temperature, to ensure optimum battery performance. “The most common causes of battery failure and reduced service life are associated with incorrect charging techniques,” says AndrewTrentelman, senior general manager: electronics, Becker Mining South Africa. “Becker Mining’s new IGBT mine traction battery chargers, which utilise insulated-gate bipolar transis- tor (IGBT) technology for quick on and off switching, are more efficient and cost effective than conventional transductor controlled, oil-cooled traction battery chargers. “These IGBT battery chargers are lightweight air cooled units, which are controlled by an intelligent micro processor circuit that acts as the main control computer, responsible for the logging, charge functions and controls. “Becker Mining’s new chargers utilise DeltaVolts/DeltaTime (DV/DT) for the precise detection of a battery’s gassing stage so the charger can terminate the second rate charge more rapidly. This technology, which prevents over-charging often associated with conventional battery charg- ers, ensures reduced charging times and lower power consumption. By reducing the charge current once DV/DT is reached, batteries are charged at a significantly lower temperature.” Enquiries: AndrewTrentelman.Tel. 011 617 6300 or email info@za.becker-mining.com