Several decades ago I had a pumping station with two vertical pump motors and soft starters. When on the generator one pump would start and reach speed with a Schneider Electric Altistart but the other pump would not reach speed. Both pumps would work fine with a Saftronics starter. We were able to supply either motor from either starter. I don't remember the final solution but it involved the generator manufacturer.
Yeah, there used to be an issue with generator AVRs and some types of soft starters because the soft start firing was affecting the AVR, which then would affect the soft starter SCR firing sequence, and it just oscillated back and forth. The generator mfrs solved the issue because it was simpler to do at their end, involving a simple filter on the AVR sensing circuit. CAT even used to sell an aftermarket retrofit filter, but they stopped a long time ago, figuring that all of the old systems had run their course.
History lesson for the day:
Ironically it was the old OLD Saftronics starters that were the problem, and all of the "children" soft start designs that they fostered in the market. Saftronics themselves fixed it later, but for all of their competitors that had copied their original Phase Locked Loop firing circuit, the problem persisted. In the earliest days of Soft Starters, there were two original players, Vectrol and
South
African Electronics, who sold under
Saftronics here in North America because of the apartheid issues. The soft starter designs that were based on the original Vectrol product (Westinghouse, Motortronics, Nordic and Allen Bradley) never had that issue because they used what's called a "picket fence" firing scheme. Everything else on the market was either brand-labeled FROM Saftronics, or copied from them (Benshaw, Baldor, Cutler Hammer, Square D.), or later imported from Europe as copies from Saftronics (Siemens, Telemecanique and Agut / GE).
