Polarity of D-C control

Polarity of device coil connections is important in preventing coil corrosion. Replies to AIEE questionnaires indicated that there was no trouble resulting from coil corrosion where the negative connection was used, while more than 50 per cent of the companies using the positive connection reported corrosion trouble. As a result of this report, the AIEE Standards committee took action as reported in ELECTRICAL ENGINEERING, December 1947, page 1250.