MIL-STD-1399-300 establishes electrical interface characteristics for shipboard equipment utilizing AC electric power to ensure compatibility between the user equipment and the electric power system. In MIL-STD-1399-300, characteristics of the electric power system are defined and tolerances are established, as well as requirements and test methods for ensuring compatibility of the shipboard user equipment with the power system. The policies and procedures established by MIL-STD-1399-300 are mandatory. This section and the basic standard are to be viewed as an integral single document for use in the design and testing of electric power systems and user equipment. This standard supersedes MIL-STD-1399-103.
In accordance with the MIL-STD-1399-300, the types of shipboard electric power to be supplied from the electric power system are classified as low voltage as follows:
- Type I power is 440 or 115 volts (V), 60 hertz (Hz) ungrounded and is the standard shipboard electric power source. Type I power is used unless a deviation is granted
- Type II power is 440 or 115 V, 400 Hz ungrounded and has only limited application. Use of Type II power requires the submittal and approval of a deviation request
- Type III power is 440 or 115 V, 400 Hz ungrounded having tighter tolerances as compared to Type II. Type III power has restricted use and its use requires the submittal and approval of a deviation request
Special power classification for avionic shops and aircraft servicing
Types of shipboard electric power only for avionic shops and aircraft servicing are as follows:
- Type I power is 115/200 V, 60 Hz, 3-phase, 4-wire, wye-grounded. This power is only provided for avionic shops.
- Type III power is 115/200 V, 400 Hz, 3-phase, 4-wire, wye-grounded. This power is only provided for avionic shops and for aircraft servicing.
Special power classification for NATO load equipment
Types of shipboard electric power supplied only for NATO load equipment are as follows:
- Type I power is 230 V, 60 Hz, 3-phase, ungrounded or 230 V, 60 Hz, single-phase, grounded or ungrounded. Its tolerances are the same as for Type I power as described in Table I except that the spike voltage will be at 1400 V peak.
Special non-standard power
For types of shipboard electric power supplied for specific industrial equipment such as washers, dryers, etc., see NAVSEA Drawings 7512881 for 120/208 Vrms loads and 7598285 for 120/240 Vrms loads. Non-standard power should comply with Type I tolerances. See 18.104.22.168 NOTE for Human Body Leakage current-voltage and frequency limits.