MIL-STD-1399 Sec 300 Part 1.pdf

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DISTRIBUTION STATEMENT A. Approved for public release. Distribution is unlimited.

METRIC

MIL-STD-1399

SECTION 300, PART 1

25 September 2018

SUPERSEDING

MIL-STD-1399(NAVY)

SECTION 300B

24 April 2008

DEPARTMENT OF DEFENSE

INTERFACE STANDARD

SECTION 300, PART 1

LOW VOLTAGE ELECTRIC POWER,

ALTERNATING CURRENT

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MIL-STD-1399-300-1

ii

FOREWORD

1. Preamble. This standard is approved for use by all Departments and Agencies of the Department of Defense.

2. Purpose. This section defines the standard interface requirements for and the constraints on the design of shipboard user equipment that will utilize shipboard alternating current (AC) low voltage electric power.

3. Nature of the interface. In any system involving power source, distribution network, and load (user equipment), the characteristics at the system and user equipment interface are mutually dependent on the design and operation of both. In order for the electric power system to perform within the established tolerances, it is necessary to place constraints on the power source, the distribution system, and the user equipment. This interface standard defines the electric power system characteristics. User equipment constraints are also established.

4. Structure. The technical content first delineates the characteristics of the shipboard electric power system at the interface in terms of voltage, frequency, continuity, and voltage waveform. Constraints on user equipment design and installation, which are necessary to achieve shipboard compatibility with and to assure these characteristics, are then established. Finally, test requirements are specified to verify conformance of user equipment to this standard.

5. Invoking the standard. Naval Sea Systems Command (NAVSEA) will consider the mission requirement of the user equipment being developed or acquisitioned. NAVSEA will then select those conditions under which the user equipment is to operate and those conditions, which the user equipment will withstand without failure, but not necessarily, operate normally. NAVSEA will also specify those tests commensurate with the equipment’s mission, which will ensure the user equipment’s satisfactory operation, the user equipment’s compatibility with the shipboard electric power system and other equipment, and the equipment’s survival.

6. NATO coordination and standardization. The standard characteristics of AC electric power supplied for U.S.

Navy ships have been coordinated with North Atlantic Treaty Organization (NATO) standardization documentation, where applicable. In particular, the standard characteristics of Type I and Type II power conform to corresponding power types specified in STANAG 1008 (Edition 9).

7. Numerical quantities. Numerical quantities are expressed in metric (SI) units.

8. Contact information. Comments, suggestions, or questions on this document should be addressed to

Commander, Naval Sea Systems Command, ATTN: SEA 05S, 1333 Isaac Hull Avenue, SE, Stop 5160, Washington

Navy Yard, DC 20376-5160 or emailed to CommandStandards@navy.mil, with the subject line “Document Comment”.

Since contact information can change, you may want to verify the currency of this address information using the

ASSIST Online database at https://assist.dla.mil.

mailto:CommandStandards@navy.mil https://assist.dla.mil/ iii

CONTENTS

PARAGRAPH PAGE

1. SCOPE

1.1 Scope

1.2 Classification

1.2.1 Special power classifications at the load interface

1.2.2 Special non-standard power

1.3 Electric power at the interface

2. APPLICABLE DOCUMENTS

2.1 General

2.2 Government documents

2.2.1 Specifications, standards, and handbooks

2.2.2 Other Government documents, drawings, and publications

2.3 Non-Government publications

2.4 Order of precedence

3. DEFINITIONS

3.1 Electric power system

3.2 Electrical interface

3.3 Electric power system ground

3.3.1 Ungrounded electric power system

3.3.2 High-resistance grounded electric power system

3.3.3 Solidly grounded electric power system

3.4 Frequency

3.4.1 Nominal frequency

3.4.2 Frequency modulation

3.4.3 Frequency tolerance

3.4.4 Frequency transients

3.4.4.1 Frequency transient tolerance

3.4.4.2 Frequency transient recovery time

3.4.5 Worst case frequency steady-state and transient excursion

3.5 Voltage

3.5.1 Nominal user voltage

3.5.2 Voltage unbalance (line-to-line)

3.5.3 Voltage modulation (amplitude)

3.5.4 Average line-to-line voltage tolerance

3.5.5 Single line-to-line voltage tolerance

3.5.6 Maximum voltage steady-state departure

3.5.7 Voltage transients

3.5.7.1 Voltage transient tolerance

3.5.7.2 Voltage transient recovery time

3.5.8 Worst case voltage steady-state and transient excursion

3.5.9 Voltage spike

3.5.10 Voltage waveform

3.5.10.1 Voltage single harmonic

3.5.10.2 Voltage single harmonic content

3.5.10.3 Voltage total harmonic distortion (THD)

3.5.10.4 Voltage deviation factor

3.6 Current

3.6.1 Current unbalance

3.6.2 Current waveform

3.6.2.1 Current single harmonic

3.6.2.2 Current single harmonic content

3.6.3 Surge/inrush current

3.6.4 Leakage current

3.6.5 Line-to-ground current

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CONTENTS

PARAGRAPH PAGE

3.6.6 Ground current

3.6.7 Ground current from the simulated human body impedance ground current test

3.6.8 Hull current

3.7 Power factor (pf)

3.7.1 Displacement power factor (dpf)

3.7.2 Distortion component (μ) of pf

3.8 Power

3.8.1 Real power

3.8.2 Reactive power

3.8.3 Apparent power

3.9 Pulse

3.10 Pulsed load

3.10.1 Peak-to-peak pulsed real power

3.11 Ramp load

3.12 Power total signal distortion (TSD)

3.13 User equipment

3.14 Emergency conditions

3.15 Mission critical equipment (MCE)

3.16 Power interruption

3.16.1 Reconfiguration time (tr)

3.16.2 Generator start time (ts)

3.17 Independent power sources

3.18 Limited-break power source

3.19 No-break power source

4. GENERAL REQUIREMENTS

4.1 Interface requirements

4.2 Conformance test requirements

4.3 User equipment

4.4 Deviations, waivers, and tailoring

5. DETAILED REQUIREMENTS

5.1 Electric power system characteristics

5.1.1 Types of power

5.1.1.1 Type I, 60-Hz power

5.1.1.2 Types II and III, 400-Hz power

5.1.2 System grounding

5.1.2.1 Ungrounded system

5.1.2.2 Grounded system

5.1.2.3 High-resistance grounded system

5.1.3 Electric plant power interruption

5.1.3.1 Using a limited-break power source

5.1.3.2 Using a no-break power source

5.1.4 Frequency and voltage excursions and decay

5.1.4.1 Type I electric power system

5.1.4.2 Types II and III electric power systems

5.1.5 Phase sequence

5.1.6 Phase angular relations

5.1.7 Electric power system protection

5.1.7.1 Type I, 60-Hz electric power system protection

5.1.7.2 Type II, 400-Hz electric power system protection

5.1.7.3 Type III, 400-Hz electric power system protection

5.1.7.4 Conditions not protected against

5.1.8 Electric power system parameters

5.1.8.1 Nominal frequency

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CONTENTS

PARAGRAPH PAGE

5.1.8.1.1 Type I, 60-Hz frequency tolerance and transient tolerance

5.1.8.1.2 Type II, 400-Hz frequency tolerance and transient tolerance

5.1.8.1.3 Type III, 400-Hz frequency tolerance and transient tolerance

5.1.8.2 Nominal user voltage

5.1.8.2.1 Type I, 60-Hz and Type II, 400-Hz power voltage tolerance and transient tolerance

5.1.8.2.2 Type III, 400-Hz power voltage tolerance and transient tolerance

5.1.8.2.3 Voltage spike characteristics

5.1.8.3 Voltage and frequency modulation

5.1.8.4 Voltage unbalance

5.1.8.5 Voltage waveform

5.2 User equipment interface requirements

5.2.1 Compatibility

5.2.2 User equipment voltage

5.2.3 Emergency conditions

5.2.3.1 Power interruptions

5.2.3.2 Power source decay

5.2.3.3 Voltage and frequency excursions

5.2.4 Grounding

5.2.5 Human body ground current limits for personnel safety

5.2.5.1 Low frequency human body ground current limits for personnel safety

5.2.5.2 High frequency human body ground current limits for personnel safety

5.2.6 Current (load) unbalance

5.2.7 User equipment pf

5.2.8 Pulsed load requirements

5.2.8.1 Pulsed load requirement for type I power by category

5.2.8.1.1 Infrequent pulsed load requirements

5.2.8.1.2 Repetitive pulsed load requirements

5.2.8.1.2.1 Pulsed power deviation limit (time domain)

5.2.8.1.2.2 Pulsed power magnitude/frequency limits (frequency domain)

5.2.8.1.2.3 Power total signal distortion (TSD) limit (frequency domain)

5.2.8.2 Pulsed load requirements for type II power by category

5.2.8.2.1 Infrequent pulsed load requirements

5.2.8.2.2 Repetitive pulsed load requirements

5.2.8.3 Pulsed load requirements for type III power by category

5.2.8.3.1 Infrequent pulsed load requirements

5.2.8.3.2 Repetitive pulsed load requirements

5.2.9 Ramp load requirement

5.2.10 Input current waveform

5.2.10.1 60-Hz user equipment greater than or equal to 1 kVA

5.2.10.2 60-Hz user equipment less than 1 kVA

5.2.10.3 400-Hz user equipment greater than or equal to 0.2 kVA

5.2.10.4 400-Hz user equipment less than 0.2 kVA

5.2.11 Surge/inrush current

5.2.12 Insulation resistance

5.2.13 Active ground detection

5.2.14 Passive ground detection

5.2.15 Voltage spikes

5.3 Test requirements

5.3.1 Grounding (susceptibility) test

5.3.1.1 Apparatus

5.3.1.2 Procedure

5.3.2 User equipment power profile test

5.3.2.1 Apparatus

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CONTENTS

PARAGRAPH PAGE

5.3.2.2 Procedure

5.3.3 Voltage and frequency maximum departure tolerance test

5.3.3.1 Apparatus

5.3.3.2 Procedure

5.3.4 Voltage and frequency transient tolerance and recovery (susceptibility) test

5.3.4.1 Apparatus

5.3.4.2 Procedure

5.3.5 Voltage spike (susceptibility) test

5.3.5.1 Apparatus

5.3.5.2 Procedure

5.3.6 Emergency conditions (susceptibility) test

5.3.6.1 Apparatus

5.3.6.2 Procedure

5.3.6.2.1 tr power interruption subtest

5.3.6.2.2 ts power interruption subtest

5.3.6.2.3 Power source decay subtest

5.3.6.2.4 Positive excursion subtest

5.3.7 Current waveform (emission) test

5.3.8 Voltage and frequency modulation (susceptibility) test

5.3.8.1 Apparatus

5.3.8.2 Procedure

5.3.9 Simulated human body impedance ground current test

5.3.9.1 Apparatus

5.3.9.2 Procedure

5.3.9.3 Method of test

5.3.10 Equipment line-to-ground voltage (susceptibility) test

5.3.10.1 Megohmmeter test

5.3.10.2 AGD test

6. NOTES

6.1 Intended use

6.2 Acquisition requirements

6.3 Subject term (key word) listing

6.4 Deviation, waiver, and tailored requirement requests

6.5 Changes from previous issue

POWER RIPPLE ANALYSIS PROCEDURE

A.1 SCOPE

A.1.1 Scope

A.2 PROCEDURE

A.3 TEST EQUIPMENT SETTINGS

A.3.1 Instrument accuracy A.3.2 Digitizer resolution A.3.3 Measurement skew A.3.4 Anti-aliasing filters

A.4 RECOMMENDED EQUIPMENT

A.4.1 Dranetz HDPQ Guide A.4.2 Yokogawa PX8000

A.5 EXAMPLE CODE

A.5.1 MATLAB functions A.5.2 MATLAB function usage A.5.3 MATLAB Function powerDFT.m A.5.4 MATLAB Function powerRippleAnalysis.m A.5.5 MATLAB Script example.m

A.6 ADDITIONAL DFT NOTES

vii

CONTENTS

PARAGRAPH PAGE

A.6.1 MATLAB’s DFT function A.6.2 Sampling frequency A.6.3 Windowing A.6.4 Signal window width A.6.5 Bin frequency A.6.6 Zero padding A.6.7 Scalloping losses A.6.8 Rectangle window with zero padding A.6.9 Windowing for low level signals A.6.10 Windowing for frequency resolution A.6.11 Coherent gain A.6.12 TSD calculation A.6.13 MATLAB FFT frequency bins A.6.14 MATLAB FFT frequency bin order A.6.15 References viii

CONTENTS

FIGURES PAGE

FIGURE 1. Typical interface of electric power system and user equipment FIGURE 2. Frequency modulation FIGURE 3. Voltage amplitude modulation FIGURE 4. Voltage transient tolerance FIGURE 5. Voltage spike FIGURE 6. Voltage spike impulse wave shape FIGURE 7. Voltage deviation factor variables FIGURE 8. Peak-to-peak pulsed real power defined FIGURE 9. Voltage and frequency decay characteristics on loss of prime mover for typical steam turbine driven generator set, Type I, 60-Hz electric power system FIGURE 10. Type I frequency tolerance and transient tolerance envelopes FIGURE 11. Type II frequency tolerance and transient tolerance envelopes FIGURE 12. Type III frequency tolerance and transient tolerance envelopes FIGURE 13. Types I and II, 440-Vrms power user voltage tolerance and transient tolerance envelopes FIGURE 14. Types I and II, 115-Vrms power user voltage tolerance and transient tolerance envelopes FIGURE 15. Type III, 440-Vrms, 400-Hz power user voltage tolerance and transient tolerance envelopes FIGURE 16. Type III, 115-Vrms, 400-Hz power user voltage tolerance and transient tolerance envelopes FIGURE 17. Pulsed power waveform and deviation example FIGURE 18. Type I pulsed power vs. frequency FIGURE 19. Sliding averaging window example FIGURE 20. Type II pulsed load power factor vs. pulsed load apparent power FIGURE 21. Type III pulsed load power factor vs. pulsed load apparent power FIGURE 22. Limit line for currents at frequencies greater than 60 Hz for equipment greater than or equal to 1 kVA FIGURE 23. Limit line for currents at frequencies greater than 60 Hz for equipment less than 1 kVA FIGURE 24. Limit line for currents at frequencies greater than 400 Hz for equipment greater than or equal to 0.2 kVA FIGURE 25. Limit line for currents at frequencies greater than 400 Hz for equipment less than 0.2 kVA FIGURE 26. Surge current limits for load equipment using Type I power FIGURE 27. Surge current limits for load equipment using Type II or III power FIGURE 28. Single-phase, 115-Vrms, Type I power voltage spike test circuit configuration FIGURE 29. Three-phase, 115-Vrms, Type I voltage spike test circuit FIGURE 30. Three-phase, 440-Vrms, Type I voltage spike test circuit configuration FIGURE 31. Three-phase, 115-Vrms, Types II and III voltage spike test circuit configuration FIGURE 32. Three-phase, 440-Vrms, Types II and III voltage spike test circuit FIGURE 33. Single-phase simulated human body impedance ground current test setup if the EUT is connected to one single-phase voltage source from (hot) line to (hot) line FIGURE 34. Single-phase simulated human body impedance ground current test setup if the EUT is connected to one single-phase voltage source from (hot) line to (neutral) line FIGURE 35. Single-phase simulated human body impedance ground current test setup if the EUT is connected to one single phase of a three-phase voltage source FIGURE 36. Three-phase simulated human body impedance ground current test setup if the EUT is connected to a three-phase voltage source FIGURE 37. Metering circuits for high and low frequency simulated human body ground current tests FIGURE 38. AGD test circuit for three-phase EUTs ix

FIGURE 39. AGD test circuit for single-phase EUTs FIGURE A-1. MATLAB output - time domain test signal with corresponding DFT with TSD results

CONTENTS

TABLES PAGE

TABLE I. Requirements and compliance tests TABLE II. Characteristics of shipboard electric power systems TABLE III. Voltage and frequency maximum departure tolerance test TABLE IV. Voltage and frequency transient tolerance and recovery test TABLE V. Single-phase system voltage spike test conditions TABLE VI. Three-phase system voltage spike test conditions TABLE VII. Emergency conditions test TABLE VIII. Voltage and frequency modulation test

EQUATIONS PAGE

EQUATION 1

EQUATION 2

EQUATION 3

EQUATION 4

EQUATION 5

EQUATION 6

EQUATION 7

EQUATION 8

EQUATION 9

EQUATION 10

EQUATION 11

EQUATION 12

EQUATION 13

EQUATION 14

EQUATION 15

1. SCOPE

1.1 Scope. This military standard section establishes electrical interface characteristics for shipboard equipment utilizing AC low voltage electric power to ensure compatibility between user equipment and the electric power system. MIL-STD-1399-300-2 describes Navy or industrial medium voltage systems. 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.

1.2 Classification. Types of shipboard low voltage electric power to be supplied from the electric power system are classified as follows:

Type I - Type I power is 440 or 115 volts root mean square (Vrms), 60 hertz (Hz) and is the standard AC shipboard electric power source. 440-Vrms interfaces are either three-phase or single-phase and are either ungrounded or high-resistance grounded. 115-Vrms interfaces are either three-phase or single-phase and are either ungrounded or solidly-grounded. Type I power is used unless a deviation is granted (see 4.4).

Type II - Type II power is 440 or 115 Vrms, 400 Hz ungrounded and has only limited application. Use of

Type II power requires the submittal and approval of a deviation request (see 4.4).

Type III - Type III power is 440 or 115 Vrms, 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 (see 4.4).

1.2.1 Special power classifications at the load interface.

a. For servicing aircraft in hangars and on flight decks, avionic shops, and hotel services:

Type I - Type I power is 115/200 Vrms, 60 Hz, three-phase, four-wire wye, grounded neutral.

b. For servicing aircraft in hangars and on flight decks, avionic shops, and Landing Craft Air Cushion

(LCAC) systems:

Type III - Type III power is 115/200 Vrms, 400 Hz, three-phase, four-wire wye, grounded neutral.

c. For NATO load equipment:

Type I - Type I power is 230 Vrms, 60 Hz, three-phase ungrounded or 230 Vrms, 60 Hz, single-phase grounded or ungrounded. Its tolerances are the same as for Type I power as described in table II except that the spike voltage will be at 1400-V peak.

1.2.2 Special non-standard power. For types of shipboard electric power supplied for specific industrial equipment such as washers, dryers, etc., see NAVSEA Drawing 302-7512881 for 120/208-Vrms rated loads and

NAVSEA Drawing 302-7598285 for 240/120-Vrms rated loads. Non-standard power should comply with Type I tolerances. Perform the tests in 5.3 at the input terminals to the transformer receiving ship’s power from the shipboard distribution power panel or the load center switchboard.

1.3 Electric power at the interface. The ship service generation sources supply electric power to the interface

(see 3.2) which feeds the user equipment as shown on figure 1. At this location, cable designations change from power or lighting designations, such as P, EP, PP, L, EL, or SF, to other or no designation change at the user equipment electric power input terminals.

NOTES:

1. Typical Power System Characteristics: Voltage, Frequency, and Emergency Conditions.

2. Typical User Equipment Constraints: Type of Power, Power Factor, Power Interruption, Grounding, Load

Unbalance, Pulsed Loads, Input Current Waveform, and Surge/Inrush Current.

FOOTNOTES:

1/ Refer to 1.3 for a description of the interface.

2/ Cables with power/lighting designations.

FIGURE 1. Typical interface of electric power system and user equipment.

Manual Bus

Transfer Device

2. APPLICABLE DOCUMENTS

2.1 General. The documents listed in this section are specified in sections 3, 4, or 5 of this standard. This section does not include documents cited in other sections of this standard or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3, 4, or 5 of this standard, whether or not they are listed.

2.2 Government documents.

2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

DEPARTMENT OF DEFENSE SPECIFICATIONS

MIL-DTL-917 - Electric Power Equipment, Basic Requirements for

MIL-DTL-24765 - Power Supply, Uninterruptible, Static (Naval Shipboard)

DEPARTMENT OF DEFENSE STANDARDS

MIL-STD-461 - Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment

MIL-STD-1399 - Interface Standard for Shipboard Systems

DEPARTMENT OF DEFENSE HANDBOOKS

MIL-HDBK-2036 - Preparation of Electronic Equipment Specifications

(Copies of these documents are available online at https://quicksearch.dla.mil.)

2.2.2 Other Government documents, drawings, and publications. The following other Government documents, drawings, and publications form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

NAVAL SEA SYSTEMS COMMAND (NAVSEA) DRAWINGS

302-7512881 - Non-Standard Power Distribution System 120/208 Vrms, with Grounded Neutral

302-7598285 - Non-Standard Power Distribution System 240/120 Vrms

802-7094558 - CVN 78 Class Aircraft Carrier Electrical Interface Characteristics

(Copies of these documents are available from the applicable repositories listed in S0005-AE-PRO-010/EDM, which can be obtained online via Technical Data Management Information System (TDMIS) at https://mercury.tdmis.navy.mil. Copies of these documents may also be obtained from the Naval Ships Engineering

Drawing Repository (NSEDR) online at https://199.208.213.105/webjedmics/index.jsp. To request an NSEDR account for drawing access, send an email to NNSY_JEDMICS_NSEDR_HELP_DESK@navy.mil.)

NAVAL SEA SYSTEMS COMMAND (NAVSEA) PUBLICATIONS

S9086-KC-STM-010/300 - Electric Plant - General

(Copies of this document are available online via Technical Data Management Information System (TDMIS) at https://mercury.tdmis.navy.mil by searching for the document number without the suffix. Refer questions, inquiries, or problems to: DSN 296-0669, Commercial (805) 228-0669. This document is available for ordering (hard copy) via the Naval Logistics Library at https://nll.ahf.nmci.navy.mil. For questions regarding the NLL, contact the NLL

Customer Service at nllhelpdesk@navy.mil, (866) 817-3130, or (215) 697-2626/DSN 442-2626.)

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2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

IEEE

IEEE 45.1 - IEEE Recommended Practice for Electrical Installations on Shipboard - Design

IEEE 45.3 - IEEE Recommended Practice for Shipboard Electrical Installations - Systems

Engineering

(Copies of these documents are available online at www.ieee.org.)

JOHNS HOPKINS UNIVERSITY TECHNICAL PAPER

Power-Specification Frequency-Domain Test and Analysis Methodology for Large Dynamic Loads

(Copies of this document are available online at http://www.jhuapl.edu/DFTProcedure.pdf.)

2.4 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

3. DEFINITIONS

3.1 Electric power system. The electric power system is the electric power generation and distribution system

(excluding electric propulsion systems) including generation, cables, switchboards, switches, protective devices, converters, transformers, and regulators up to the user equipment interface.

3.2 Electrical interface. The electrical interface is the boundary between the electric power system and the user equipment where the electric power system characteristics (see 5.1) and the user equipment compatibility requirements (see 5.2) apply. Figure 1 illustrates the interface.

3.3 Electric power system ground. Ground is a plane or surface used by the electric power system as a common reference to establish zero potential. Usually, this surface is the metallic hull of the ship. On a nonmetallic hull ship, a special ground system is installed for this purpose.

3.3.1 Ungrounded electric power system. An ungrounded electric power system is a system that is intentionally not connected to the metal structure or the grounding system of the ship, except for test purposes.

Although intentionally not system grounded, there exists an impedance to ground from each power line due to the always present parasitic capacitance to ground. An ungrounded electric power system can continue to perform normally if one line conductor becomes solidly grounded. However, an ungrounded system may be subject to over-voltages greater than five times nominal voltage as a result of an inductive arcing ground between one line and ground. Tolerance of a single line ground fault is managed by limiting the AC line-to-ground impedance

(capacitance) such that the single fault ground current will be tolerated by the electric plant.

3.3.2 High-resistance grounded electric power system. A high-resistance grounded electric power system is a system that employs an intentional high resistance between the electric system neutral and ground. High-resistance grounding provides the same advantages of ungrounded systems (i.e., the system can continue to perform normally with one line grounded) yet limits the severe transitory over-voltages associated with ungrounded systems.

3.3.3 Solidly grounded electric power system. A solidly grounded electric power system is a system in which at least one conductor or point (usually the neutral point of the transformer or generator winding) is intentionally and effectively connected to system ground. A single ground fault from one line to ground will produce high fault current that should cause selective tripping of protective circuit breakers interrupting power service continuity.

3.4 Frequency. Units are in Hertz (Hz). It is denoted by the symbol “f”.

3.4.1 Nominal frequency. Nominal frequency (fnominal) is the designated frequency in Hz in accordance with the

Type Power Classification.

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http://www.ieee.org/ http://www.jhuapl.edu/DFTProcedure.pdf

3.4.2 Frequency modulation. Frequency modulation is the periodic variation in frequency during normal operation, calculated by equation 1 and shown on figure 2; the permitted modulation is provided in table II, Item 2.

The periodicity of frequency modulation should be considered as greater than one cycle, but not exceeding 10 seconds.

Frequency modulation (percent) = ( fmaximum− fminimum

2 × fnominal ) × 100

EQUATION 1

FIGURE 2. Frequency modulation.

3.4.3 Frequency tolerance. Frequency tolerance is the allowed variation from nominal frequency expressed as a percent of the nominal frequency; the permitted tolerance is provided in table II, Item 3. This tolerance is the maximum permitted value during normal operation including variations caused by small load changes, environmental effects (temperature, humidity, vibration, and inclination), and drift, excluding modulation and transients. The frequency tolerance may be calculated using equation 2.

Frequency tolerance (percent) = ( fmeasured− fnominal fnominal ) × 100

Where:

fmeasured is the measured frequency and fnominal is the nominal frequency provided in table II, Item 1.

EQUATION 2

3.4.4 Frequency transients. A frequency transient is a sudden change in frequency that goes outside the frequency tolerance limits and returns to and remains within these limits within a specified recovery time (longer than 1 millisecond) after the initiation of the disturbance such as large load changes.

3.4.4.1 Frequency transient tolerance. Frequency transient tolerance is the allowed variation from nominal frequency expressed as a percent of the nominal frequency during transient conditions; the permitted tolerance is provided in table II, Item 4. The frequency transient tolerance may be calculated using equation 3.

Frequency transient tolerance (percent) = ( ftransient− fnominal fnominal ) × 100

Where:

ftransient is the measured frequency transient and fnominal is the nominal frequency provided in table II, Item 1.

EQUATION 3

3.4.4.2 Frequency transient recovery time. Frequency transient recovery time is the time elapsed from the instant the frequency first goes outside the frequency tolerance limits until the instant the frequency recovers and remains within the frequency tolerance limits.

3.4.5 Worst case frequency steady-state and transient excursion. The worst case frequency excursion is the allowed excursion resulting from a combination of steady-state characteristics (modulation, tolerance) and transient characteristics with no individual characteristic exceeding its limits in table II; the permitted excursion is provided in table II, Item 5. This does not include emergency conditions.

3.5 Voltage. Units are in Volts (V). Unless specified as peak or DC quantities, voltages in this standard are root-mean-square (rms) values. Tolerances are expressed in percent of the nominal user voltage. It is denoted by the symbol “V”.

3.5.1 Nominal user voltage. Nominal user voltage (Vnominal) is the designated voltage at the interface. As shown on figure 1, the generated or transformed source voltage is normally 450, 208, or 120 Vrms, and taking into consideration cable impedance voltage drop, the interface voltage should be set to 440, 200, or 115 Vrms by adjusting the source voltage.

3.5.2 Voltage unbalance (line-to-line). The line-to-line voltage unbalance is the difference of the maximum and minimum line-to-line voltages divided by the nominal line-to-line voltage; the permitted unbalance is provided in table II, Item 8. Voltages are either all rms or all peak (sinusoidal crest) values as shown in equation 4.

Line-to-line voltage unbalance (percent) = ( Vmaximum− Vminimum

Vnominal ) × 100

Where:

Vmaximum is the maximum line-to-line voltage, Vminimum is the minimum line-to-line voltage, and

Vnominal is the nominal line-to-line voltage provided in table II, Item 7.

EQUATION 4

3.5.3 Voltage modulation (amplitude). Voltage modulation is the periodic voltage variation (peak-to-valley) of a single line-to-line user voltage, calculated by equation 5 and shown on figure 3; the permitted modulation is provided in table II, Item 9. The periodicity of voltage modulation should be considered to be longer than one cycle time at nominal frequency and less than 10 seconds. Voltages used in the following equation are either all rms or all peak (sinusoidal crest) values. Vnominal is provided in table II, Item 7.

Voltage modulation (percent) = ( Vmaximum− Vminimum

2 × Vnominal ) × 100

Where:

Vmaximum is the maximum line-to-line voltage, Vminimum is the minimum line-to-line voltage, and

Vnominal is the nominal line-to-line voltage provided in table II, Item 7.

EQUATION 5

FIGURE 3. Voltage amplitude modulation.

3.5.4 Average line-to-line voltage tolerance. The average line-to-line user voltage tolerance is the allowed departure of the average of the line-to-line voltages from the nominal voltage as a percent of the nominal voltage.

This average line-to-line voltage tolerance is the maximum permitted value (provided in table II, Item 10) during normal operation including variations caused by small load changes, environmental effects (temperature, humidity, vibration, and inclination), and drift, excluding voltage unbalance, modulation, and transients. The average line-to-line voltage tolerance is calculated in equation 6. Voltages are either all rms or all peak (sinusoidal crest) values.

Average line-to-line voltage tolerance (percent) = ( Vaverage− Vnominal

Vnominal ) × 100

Where:

Vaverage is the sum of the line-to-line voltages divided by the number of line-to-line voltages and

Vnominal is the nominal user voltage provided in table II, Item 7.

EQUATION 6

3.5.5 Single line-to-line voltage tolerance. The single line-to-line user voltage tolerance is the allowed departure of any single line-to-line voltage from nominal user voltage expressed as a percent of the nominal voltage.

This line-to-line voltage tolerance is the maximum permitted value (provided in table II, Item 11) during normal operation including variations caused by small load changes, environmental effects (temperature, humidity, vibration, and inclination), and drift, excluding voltage unbalance, modulation, and transients. The line-to-line voltage tolerance is calculated in equation 7. Voltages are either all rms or all peak (sinusoidal crest) values.

Single line-to-line voltage tolerance (percent) = ( VLL− Vnominal

Vnominal ) × 100

Where:

VLL is each line-to-line voltage and Vnominal is the nominal user voltage provided in table II, Item 7.

EQUATION 7

3.5.6 Maximum voltage steady-state departure. The maximum voltage departure is the allowed departure resulting from a combination of steady-state characteristics (unbalance, modulation, and tolerance) with no individual characteristic exceeding its limits in table II; the permitted maximum steady-state voltage departure is provided in table II, Item 12.

3.5.7 Voltage transients. A voltage transient (excluding voltage spikes [see 3.5.9]) is a sudden change in voltage (longer than 1 millisecond) that exceeds, positively or negatively, the user voltage tolerance limits and returns to and remains within these limits within a specified recovery time after the initiation of the disturbance such as large load changes.

3.5.7.1 Voltage transient tolerance. Voltage transient tolerance is the allowed variation from nominal voltage expressed as a percent of the nominal voltage during transient conditions; the permitted voltage transient tolerance is provided in table II, Item 13. The voltage transient tolerance may be calculated using equation 8. Voltages are either all rms or all peak (sinusoidal crest) values.

Voltage transient tolerance (percent) = ( Vtransient− Vnominal

Vnominal ) × 100

Where:

Vtransient is the measured momentary line-to-line transient voltage and Vnominal is the nominal user voltage provided in table II, Item 7.

EQUATION 8

3.5.7.2 Voltage transient recovery time. Voltage transient recovery time is the time elapsed from the instant the voltage first goes outside the user voltage tolerance limit until the instant when the voltage recovers and remains within the user voltage tolerance limit. A typical low level transient voltage is shown on figure 4.

FIGURE 4. Voltage transient tolerance.

3.5.8 Worst case voltage steady-state and transient excursion. The worst case voltage excursion is the allowed excursion resulting from a combination of steady-state characteristics (unbalance, modulation, and tolerance) and transient characteristics with no individual characteristic exceeding its limits in table II; the permitted worst case voltage excursion is provided in table II, Item 14. This does not include emergency conditions.

3.5.9 Voltage spike. A voltage spike is a voltage change or impulse of very short duration (less than

1 millisecond) represented on figure 5. Voltage spikes in shipboard power systems are generally of an oscillatory nature and not unidirectional as those often used in testing. The impulse waveform shown on figure 6 is the characteristic voltage spike used for test purposes. The spike magnitude is measured in peak voltage (Vp).

FIGURE 5. Voltage spike.

(NOTE: 2500-V peak and 1000-V peak spikes ride on the fundamental AC voltage waveform.)

FIGURE 6. Voltage spike impulse wave shape.

3.5.10 Voltage waveform. The voltage waveform is a voltage vs. time function.

3.5.10.1 Voltage single harmonic. A voltage single harmonic is a sinusoidal component of the voltage’s periodic waveform having a frequency that is an integral multiple of the fundamental frequency.

3.5.10.2 Voltage single harmonic content. The voltage single harmonic content of a voltage wave is the ratio, in percentage, of the rms value of that harmonic to the rms value of the fundamental.

3.5.10.3 Voltage total harmonic distortion (THD). The THD of a voltage wave is the ratio in percentage of the rms value of the residue (after elimination of the fundamental) to the rms value of the fundamental, calculated by equation 9.

Voltage THD (percent) = 100 × √∑ ( 𝑉ℎ

𝑉𝑓𝑢𝑛𝑑𝑎𝑚𝑒𝑛𝑡𝑎𝑙 ℎ≥2

Where:

Vh is the rms voltage of individual harmonics h ≥ 2

Vfundamental is the rms voltage at the fundamental frequency

EQUATION 9

3.5.10.4 Voltage deviation factor. The voltage deviation factor of the voltage waveform is the ratio (a/b) where

“a” is the maximum deviation between corresponding ordinates of the waveform and of the equivalent sine wave and “b” is the maximum ordinate of the equivalent sine wave when the waveforms are superimposed in such a way that they make the maximum difference as small as possible. This is calculated by equation 10 and shown on figure 7. NOTE: The equivalent sine wave is defined as having the same frequency and the same rms voltage as the waveform being tested.

Voltage deviation factor (percent) = ( Maximum deviation

Maximum ordinate of the equivalent sine wave ) × 100

EQUATION 10

FIGURE 7. Voltage deviation factor variables.

3.6 Current. Units are in Amperes (A). Unless specified as peak or DC quantities, currents in this standard are rms values. It is denoted by the symbol “I”.

3.6.1 Current unbalance. Current unbalance for three-phase loads is the ratio of the maximum line current magnitude minus the minimum line current magnitude to the average of the three line current magnitudes in amperes, shown in equation 11. Currents used in the following equation are rms values.

Current unbalance (percent) =

/3III

II

CBA

lineminlinemax

EQUATION 11

3.6.2 Current waveform. The current waveform is a current vs. time function.

3.6.2.1 Current single harmonic. A current single harmonic is a sinusoidal component of the current’s periodic waveform having a frequency that is an integer multiple of the fundamental frequency. There may exist currents at individual frequencies that are not harmonics and may be produced by switching frequencies internal to equipment.

3.6.2.2 Current single harmonic content. The current single harmonic content of a current waveform is the ratio, in percentage, of the rms value of that harmonic to the rms value of the fundamental.

3.6.3 Surge/inrush current. Surge/inrush current is a sudden change in line current to a user equipment that occurs during start-up or after a power interruption or as a result of a change to the operating mode. Typically, the surge current will rise to a maximum value in a few milliseconds and decay to rated value in several milliseconds to several seconds. The limit in 5.2.11 is evaluated as the ratio of the highest peak surge/inrush current to the peak of the rated current of the equipment.

3.6.4 Leakage current. Leakage current is energized circuit current from a conductor to another conductor or ground through parasitic capacitance and insulation resistance.

3.6.5 Line-to-ground current. Line-to-ground current is current from the line conductor through an impedance due to filter components-to-ground or leakage current.

3.6.6 Ground current. Ground current is current through a grounding conductor to ground, equal to the phasor summation of all the line-to-ground currents and is ideally equal to zero. This current only appears when there is an imbalance in the phases of the line-to-ground circuit and has a path to return to a similar circuit on the same distribution system.

3.6.7 Ground current from the simulated human body impedance ground current test. This is ground current due to unbalanced leakage and/or filter current that passes through a simulated human body circuit impedance magnitude of 1986 ohms and an angle of -5.37 degrees at 60 Hz using the metering circuit on figure 36. This current may appear when the load equipment becomes ungrounded and is measured through the simulated human body impedance.

3.6.8 Hull current. Hull current is the phasor summation of ground current through the hull of the ship.

3.7 Power factor (pf). The pf is the ratio of the real power in watts to the product of the rms voltage and rms current. For voltage waveforms with distortion, pf can be approximated as the product of the displacement pf (dpf)

(see 3.7.1) and the distortion (μ) (see 3.7.2). This is shown in equation 12.

pf = P (watts)

Vrms Irms ≈ μ dpf

EQUATION 12

3.7.1 Displacement power factor (dpf). The dpf is defined as the cosine of the angle difference between the fundamental frequency component of the input voltage and the fundamental frequency component of the current, shown in equation 13. The dpf is the same as the pf in linear circuits with sinusoidal voltages and currents. The angle determines whether the pf is leading or lagging. A positive value of the angle means that the current lags the voltage (lagging pf, inductive load). A negative value of the angle means that the current leads the voltage (leading pf, capacitive load).

dpf = cos IV

Where:

φv is the angle of the fundamental frequency component of the input voltage φI is the angle of the fundamental frequency component of the current

EQUATION 13

3.7.2 Distortion component (μ) of pf. The distortion component (μ) of pf is the ratio of the rms magnitudes of the fundamental frequency current to the total current, shown in equation 14.

μ = Ifundamental

Itotal

Ifundamental is the rms value of the fundamental frequency current

Itotal is the rms value of the total current, which is the square root of the sum of the squares of the fundamental and harmonic currents

EQUATION 14

3.8 Power. Quantity that consists of real, reactive, and apparent power.

3.8.1 Real power. Real power is the average of the product of the current and voltage over time. As shown in equation 12, it is also the product of the rms voltage and rms current multiplied by the pf. The unit of real power is the watt. Real power provides work over time. It is denoted by the symbol “P”.

3.8.2 Reactive power. Reactive power is defined as the product of the rms voltage and rms current multiplied by a reactive factor. Reactive power can be calculated as the square root of the difference between the square of the apparent power and the square of the real power. The unit of reactive power is volt-ampere reactive (VAR).

Reactive power provides no net energy transfer over time; the average instantaneous reactive power over a fundamental cycle period is 0. It is denoted by the symbol “Q”.

3.8.3 Apparent power. Apparent power is defined as the product of the rms voltage and the rms current. The unit of apparent power is volt-ampere (VA). Apparent power can be calculated as the square root of the sum of the squares of real and reactive power. It is denoted by the symbol “S”.

3.9 Pulse. A pulse is a brief excursion of power lasting longer than one cycle at nominal frequency and less than 10 seconds.

3.10 Pulsed load. A pulsed load is user equipment that demands infrequent or repetitive power input that could be supplemented by energy storage. Infrequent events are defined as events occurring no more than once every

120 seconds. A repetitive power input creates a dynamic waveform. An example of a pulsed load is sonar or radar user equipment. Pulsed loading may result in unwanted modulation in the system voltage amplitude and frequency and needs to be constrained to enable acceptable responses of the voltage regulation and prime mover speed governor systems.

3.10.1 Peak-to-peak pulsed real power. For a given window of observation, the peak-to-peak pulsed real power is the difference between the maximum instantaneous value and the minimum instantaneous value as shown on figure 8.

FIGURE 8. Peak-to-peak pulsed real power defined.

3.11 Ramp load. A ramp load is user equipment that is applied to the electrical system causing a smooth rise in power or small increasing step increments of the total load.

3.12 Power total signal distortion (TSD). The TSD of a real-power waveform is the ratio in percentage of the value of the square root of the sum of squares of the power magnitudes at their individual frequencies to the square root of 2 times the average power magnitude, calculated by equation 15 in its generic form. When performing a

DFT on the power signal, which is an estimate of the frequency content, the noise characteristics of the DFT are affected by windowing and zero padding. This effect is captured in a term called equivalent noise bandwidth

(ENBW), which requires a modification to equation 15, shown in A.2 Step 11. Further information can be found in

The Johns Hopkins University Applied Physics Laboratory technical paper entitled Power-Specification

Frequency-Domain Test and Analysis Methodology for Large Dynamic Loads.

Power TSD (percent) = 100 × √∑ ( 𝑃𝑠

√2

𝑃𝑎𝑣 𝑠

Ps is the zero-to-peak real power amplitude at individual signal frequency s

1 Hz ≤ s ≤ 2 kHz

Pav is the average real power over a specified time period determined by the application

EQUATION 15

3.13 User equipment. User equipment is any system or equipment that uses electric power from the shipboard electric power system.

3.14 Emergency conditions. Emergency conditions are unexpected occurrences of a serious nature that may result in electrical power system deviations. Emergency conditions include, but are not limited to, battle damage and malfunction or failure of equipment. Conditions may include power interruptions, voltage and frequency excursions, and decays. Emergency conditions characteristics are provided in table II, Items 20 through 23.

3.15 Mission critical equipment (MCE). MCE is equipment designated by NAVSEA to remain operational during emergency conditions.

3.16 Power interruption. A power interruption is a condition where the ship service power is not being supplied for a period of time. Power interruptions are evaluated with respect to two time periods, reconfiguration time (tr) and generator start time (ts).

3.16.1 Reconfiguration time (tr). tr is the maximum duration of a power interruption that an interface (user equipment) will experience due to source transfer, typically up to 5 seconds. tr consists of the detection (of non-compliant user power) latency interval, the bus transfer interval, and the transient recovery interval (to compliant user power). The detection latency interval is the period of time from when the bus voltage and frequency deviates from compliant power to the time at which this deviation has been detected. The bus transfer interval is the period of time from when the adverse bus conditions are detected requiring initiation of a transfer up to the completion of the transfer. The transient recovery interval is the period of time from the completion of transfer to compliant power. User equipment including MCE (see 3.15) will be exposed to power interruption during this time period; MCE is required to provide the needed internal energy storage for continued operation. tr does not take into account bringing on additional generation capacity. Reconfiguration time is identified in

IEEE 45.3.

3.16.2 Generator start time (ts). ts is the maximum duration of a power interruption that an interface (user equipment) will experience due to the time needed to add generation capacity, including system protection coordination time, typically up to 5 minutes. User equipment including MCE will be exposed to power interruption during this time period; MCE needs to restart on its own or a no-break source (see 3.19) may be used for continued operation. Generator start time is identified in IEEE 45.3.

3.17 Independent power sources. Two power sources are independent if a single fault cannot result in a power interruption on both power sources at the same time.

3.18 Limited-break power source. A limited-break power source consists of a switching device supplied by two or more independent, isolated power sources. A limited-break power source incorporates an automatic means for detecting failure of a power source and for transferring the user equipment load to another power source within a specified time period. Two examples of a limited-break power source are an electromechanical automatic bus transfer (ABT) switch and a solid-state automatic bus transfer (SABT) switch. The limited-break source provides power continuity at the load interface during a loss of power during time tr by switching between normal and alternate power feeds. The limited-break transfer time is considered part of the tr power interruption seen by the user equipment.

3.19 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 normal power is not available. A no-break power source may be an uninterruptible power supply (UPS) which is supplied by independent power sources with a practically instantaneous transfer between sources; one power source may be derived from energy storage. The no-break supply characteristics are continuously held within specified limits to produce power in accordance with this standard’s requirements. The no-break power source can supply compliant power to user equipment through the tr or ts time period, as required.

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-HDBK-2036 may be used as a guide for tailoring of requirements.

4.2 Conformance test requirements. Requirements and tests (see table I and 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.

Formal testing shall not commence…