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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.zaUnderground 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.comROUND UP
DRIVES, MOTORS + SWITCHGEAR