MIL-STD-1399-3008
3.9 Pulsed load. A pulsed load may be user equipment, which demands frequent or regular repeated power input. A pulsed load is measured as the average power during the pulse interval minus the average power during the same interval immediately preceding the pulse. An example of a pulsed load is sonar or radar. A pulsed load can result in modulation in the system voltage amplitude and frequency.
3.10 Ramp load. A ramp load is a load that is applied to the electrical system as a smooth ramp or in steps
(increments of the total load).
3.11 User equipment. User equipment is any system or equipment that uses electric power from the shipboard electric power system.
3.12 Emergency condition. An emergency condition is an unexpected occurrence of a serious nature that may result in electrical power system deviations as specified under emergency conditions. Emergency conditions include but are not limited to battle damage and malfunction/failure of equipment.
3.13 Limited-break power source. A limited-break power source is a power source provided by one or two or more independent power sources incorporating automatic means for detecting failure of the power source and for transferring the user equipment load to another power source within a specified time period.
3.14 No-break power source. A no-break power source is a device which maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility power is not available.
4. GENERAL REQUIREMENTS
4.1 Interface requirements. The specific interface requirements and constraints established herein are mandatory and shall be adhered to regarding any aspect of shipboard electrical power systems or user equipment designs to which these requirements and constraints apply, including systems and equipment design, production, and installation (see MIL-STD-1399). MIL-HD8K-2036 may be used as a guide for tailoring of requirements.
4.2 Conformance test requirements. Requirements and tests (see 5.3) to ensure conformance of equipment to the interface requirements and constraints incorporated in this standard shall be included in the electric power system and user equipment specifications. Conformance of requirements (see 5.3) shall be verified by test.
4.3 User equipment. User equipment shall operate from a power system having the characteristics of Table I and shall be designed within these constraints in order to reduce adverse effects of the user equipment on the electric power system. Test methods are included for verification of compatibility. User equipment to be installed on ships built to superseded versions of this standard shall meet the most stringent demands of the applicable version.
4.4 Deviations. The power interfaces in this standard are based on a traditional AC electric power system. To meet the intent of this section for non-traditional electric power systems, deviation of requirements will be considered. The deviation provisions in MIL-STD-1399 shall be adhered to during the early development stage of user equipment, as specified (see 6.2 and 6.5).
5. DETAILED REQUIREMENTS
5.1 Electric power system characteristics. The shipboard electric power system serves a variety of user equipment such as aircraft elevators, air conditioners, communication equipment, weapon systems, and computers. Electric power is centrally generated and distributed throughout the ship from the switchboard to power panels and finally to the user equipment served. Ship design requires that conversion equipment be minimized and that most equipment served be designed to operate from the Type I, 60 Hz power system. Performance of the ship can best be served by minimizing the requirement for Types II or III, 400 Hz power. Characteristics of shipboard electric power systems at the interface shall be as specified in Table I. For 115/200 V, 4-wire grounded systems as specified in
5.1.6.2 (c) and (d), the characteristics apply to line to neutral power unless the parameter is inappropriate; for example, line balance would not apply. Type II or III power is provided by deviation only (see 4.4 and 6.5). Type I,
60 Hz power shall be used for new user equipment development unless a deviation is granted. Frequency will not decrease to 0 (minus 100 percent) without a decrease in voltage. Figure 8, 5.1.3.3, and 5.1.3.4 shall apply.
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