MIL-STD-1399-300 Electric Power, Alternating CurrentThis military standard section establishes electrical interface characteristics for shipboard equipment utilizing AC electric power to ensure compatibility between user equipment and the electric power system. Characteristics of the electric power system are defined and tolerances are established, as well as requirements and test methods for ensuring compatibility of shipboard user equipment with the power system. The policies and procedures established by MIL-STD-1399 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.

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MIL-STD-1399-3008

TA8LE I. Characteristics of shipboard electric power systems. (NOTE: Characteristic percentages are defined in Section 3.)

Characteristics	Type I	Type II	Type III
Frequency
1. Nominal frequency	60 Hz	400 Hz	400 Hz
2. Frequency tolerance	±3% (±5% for submarines)	±5%	±0.5%
3. Frequency modulation	0.5%	0.5%	0.5%
4. Frequency transient tolerance	±4%	±4%	±1%
5. Worst case frequency excursion from nominal resulting from items 2, 3, and 4 combined, except under emergency conditions	±5.5%	±6.5%	±1.5%
6. Recovery time from items 4 or 5	2 seconds	2 seconds	0.25 second
Voltage
7. Nominal user voltage	440, 115, 115/200 Vrms	440, 115 Vrms	440, 115, 115/200 Vrms
8. Line-to-line voltage unbalance	3% (0.5% for 440 Vrms, 1% for 115 Vrms for submarines)	3%	2%
9. User voltage tolerance
a. Average line-to-line voltage from nominal	±5%	±5%	±2%
b. Line-to-line voltage from nominal, including items 8 and 9.a	±7%	±7%	±3%
10. Voltage modulation	2%	2%	1%
11. Maximum departure voltage from nominal resulting from items 8, 9a, 9b, and 10 combined, except under transient or emergency conditions	±8%	±8%	±4%
12. Voltage transient tolerance	±16%	±16%	±5%
13. Worst case voltage excursion from nominal resulting from items 8, 9.a, 9.b, 10 and 12 combined, except under emergency conditions	±20%	±20%	±5.5%
14. Recovery time from item 12 or item 13	2 seconds	2 seconds	0.25 second
15. Voltage spike (± peak value)	2.5 kV (440 Vrms sys) 1.0 kV (115 Vrms sys)	2.5 kV (440 Vrms sys) 1.0 kV (115 Vrms sys)	2.5 kV (440 Vrms sys) 1.0 kV (115 Vrms sys)
Waveform (voltage)
16. Maximum total harmonic distortion	5%	5%	3%
17. Maximum single harmonic	3%	3%	2%
18. Maximum deviation factor	5% (3% for submarines)	5%	5%
Emergency conditions
19. Frequency excursion	-100% to +12%	-100% to +12%	-100% to +12%
20. Duration of frequency excursion	2 minutes	2 minutes	2 minutes
21. Voltage excursion	-100% to +35%	-100% to +35%	-100% to +35%
22. Duration of voltage excursion
a. Upper limit (+35%)	2 minutes	0.17 second	0.17 second
b. Lower limit (-100%)	2 minutes	2 minutes	2 minutes