Freda Rebecca Gold Mine

Saftronics was contracted to supply Freda Rebecca Gold Mine which is located in Bindura, Zimbabwe, a Korndörfer motor starter for their Synchronous AC Motor together with the DC excitation regulation for the rotor circuit. The Synchronous Motor is an old but refurbished Brown Boveri Motor built in 1975 on a Mill application.

Saftronics supplied the Main Incomer Switch-Gear rated for 3.3kV, the Korndörfer (Auto-Transformer) including all motor & circuit protection relays and equipment and the output AC Contactors. The Korndörfer starter panel was designed and rated for two starts every hour with a, 15 seconds starting time. The Cast-Resin Transformer design included 4 taps at 55%, 65%, 75% & 100% of 3.3kV but all rated at 3,000kVA.

The DC Excitation Controller panel included a 15” HMI touch screen display for SCADA (Supervisory Control and Data Acquisition) allowing for local operation of the complete motor starting sequence and operational monitoring of all energy values. The Motor Stators Power Factor is monitored and controlled by the Saftronics DC Excitation drive (DD6-600). By regulating the DC into the Rotor windings of the Synchronous motor, near unity power factor can be achieved.