| 2798571 | Saturable reactor control | 1957-07-09 | ||
| 2771150 | Protective relay circuits | 1956-11-20 | ||
| 2742104 | Automatic voltage control of electrostatic precipitator with saturable reactor | 1956-04-17 | ||
| 2675092 | System for energizing electrical precipitators | 1954-04-13 |