Tests conducted on two special large motors on a versatile test bed

GEC Alstom Large Machines, Benoni are manufacturers of high power, high and low voltage induction motors. This paper is a description of the testing that was conducted on two particular special machines that the author had the privilege of participating in the design of and was responsible for co-coordinating, designing and managing the testing. The machines are a set of four 2070 kW 6600 V 6 pole 630 frame 50 Hz wound rotor induction motors for constant torque mill drive application with a rotor drive to operate with a speed range from 80 - 120% of synchronous speed and a 4375 kW 2 Pole 3500 Volt 900 frame 16 Hz cage induction motor mill drive for operation with a induction motor cycloconverter drive. The challenge was to conduct full load and run testing of these machines at the operating frequency and speed. The wound rotor machine was qualified at full load at both extremes of the speed range and at synchronous speed in conjunction with the rotordrive. The cage induction motor was run on no load at 16Hz. This paper describes how this testing was achieved.