Specifications include, but are not limited to: B. Low-voltage auxiliary and control power. 1. Electrical power for ac control and instrumentation equipment: a. Provide devices necessary for proper operation and protection of equipment during electrical power supply and ambient temperature fluctuations specified. b. Design for continuous operation at any voltage from 85% to 110% of nominal voltage. Dropout voltage shall be 60% of nominal for relays and 75% for contactors and starters. 2. Electrical power for dc devices: a. Design for continuous operation on ungrounded station battery system, capable of maintaining operation at any voltage from 80% to 112% of nominal voltage. b. Electrical devices served shall not impose ground connection on supply.