Saftronics was approached by a Gauteng-based motor rewinding company to provide a solution for their No-Load AC Motor Test Facility in Johannesburg. The client required a selectable supply of 3,300 V, 6,600 V, or 11,000 V for testing rewound AC motors. Their existing system relied on an alternator (genset) supplying a step-up transformer and starting the motors Direct-On-Line (DOL).

Saftronics proposed a solid-state solution that not only reduces energy costs but also makes the testing process safer and more efficient for test-bay technicians. The Saftronics Emperor range of medium-voltage frequency inverters was offered as the solution. With an output capability of 0–11,000 V AC and 0–120 Hz, the system covers all three voltage ranges required by the client in a single package.

This solution eliminates the need for switching transformer taps for specific motor voltages, waiting for the genset to start up, and manually measuring motor current and voltage with handheld instruments. Instead, technicians can simply program the motor parameters into the VFD, and the drive is ready to operate the specified motor.

All motor power measurements are available directly from the VFD. Through industrial communication protocols, these values can be easily downloaded and included in the test certificate.