PD08WRGBGBEA04.pdf

CAGE 98752

PD08WRGBGBEA04

26 FEB 2008

72KW/90KVA GENERATOR SET

PURCHASE DESCRIPTION

1.0 SCOPE

1.1 Coverage. This document covers the requirement for a 72 KW/90KVA Generator, herein referred to as Ground Power Unit (GPU), which is used to provide 400 Hz, 28VDC, and 270 VDC power for various aircraft maintenance tasks on current Air Force aircraft.

The GPU shall be the latest state of the art design and shall comply with the requirements of this document unless specified otherwise by the governing contract.

2.0 APPLICABLE DOCUMENTS

2.1 General. The documents listed in this section are specified in Sections 3, 4, or 5 of this specification. This section does not include documents cited in other sections of this specification 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 specification, whether or not they are listed. In all instances the most current revision/date of the document shall be used.

2.2 Government documents.

2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks of the exact revision listed below form a part of this specification to the extent specified herein.

FEDERAL STANDARDS

FED-STD-595B Colors used in Government Procurement

Comments, suggestions, or questions on this document should be addressed to: WR-ALC/LEEG, Robins AFB, GA 31098-1611. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database at www.dodssp.daps.mil. C N/A

AMSC N/A

AMSC N/A FSC 6115

Distribution Statement A. Approved for public release; distribution is unlimited

INCH POUND

Comments, suggestions, or questions on this document should be addressed to: WR-ALC/642 CBSG/GBEA, Robins AFB, GA 31098-1813. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database at www.dodssp.daps.mil.

DEPARTMENT OF DEFENSE SPECIFICATIONS

MIL-DTL-0053030B Primer Coating, Epoxy, Water Reducible, Lead and Chromate Free

MIL-DTL-81706B1 Chemical Conversion Materials for Coating Aluminum and Aluminum Alloys MIL-P-53030A2 Primer Coating, Epoxy, Water Reducible, Lead and Chromate Free MIL-PRF-23377JA2 Primer Coatings: Epoxy, High-Solids MIL-PRF-26915D Primer Coating, for Steel Surfaces MIL-PRF-85285DA1 Coating: Polyurethane, Aircraft and Support Equipment

DEPARTMENT OF DEFENSE STANDARDS

MIL-STD-130N Identification Marking of U.S. Military Property MIL-STD-209K Lifting and Tiedown Provisions MIL-STD-461F Requirements for the Control of Electromagnetic Interference

Characteristics of Subsystems and Equipment MIL-STD-704F Aircraft Electrical Power Characteristics MIL-STD-705C Generator Sets, Engine Driven Methods of Tests and Instructions MIL-STD-810FC3 Environmental Engineering Considerations and Laboratory Tests MIL-STD-882D Standard Practice for System Safety MIL-STD-889BC3 Dissimilar Metals MIL-STD-1472FC1 Human Engineering

DEPARTMENT OF DEFENSE HANDBOOKS

MIL-HDBK-781A Handbook for Reliability Test Methods, Plans, and Environments for Engineering, Development, Qualification, and Production

MIL-HDBK-1791 Designing for Internal Aerial Delivery in Fixed Wing Aircraft

(Copies of these documents are available online at http://assist.daps.dla.mil/quicksearch/ or www.dodssp.daps.mil or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.)

2.3 Non-government publications. The following documents of the exact revision listed below form a part of this document to the extent specified herein.

American National Standards Institute (ANSI)

ANSI C2 2007 National Electrical Safety Code

(Application for copies should be addressed to ANSI, 1819 L St. NW, 6th Floor, Washington DC 20036, www.ansi.org.)

National Electrical Manufacturers Association (NEMA)

MG-1 2007 Motors and Generators MG-2 2001 Safety Standard for Construction and Guide for Selection, Installation, and Use of Electric Motors WD 6 2002 Wiring Devices-Dimensional Specifications

(Applications for copies should be addressed to NEMA, 1300 North 17th Street, Suite 1847, Rosslyn, VA, 22209, www.nema.org.)

National Fire Protection Association (NFPA)

NFPA 70 2008 National Electric Code

(Application for copies should be addressed to NFPA, Batterymarch Park, Quincy MA 02169- 7471, www.nfpa.org.)

Society of Automotive Engineers (SAE)

AS 21378 2004 Plugs and Cable Assemblies, External Power, Aircraft, 230/400 Volt, 400 Hertz

AS 8090 1997 Equipment, Towed Aerospace Ground, Mobility AS 90328 2000 Cable Assembly External Electric Power, Aircraft, 115/200 Volt, 400 Hertz AS 90347 2004 Cable Assembly, External Electric Power, Aircraft 28 Volt DC, Operating Power AS 90362 2002 Connector, Receptacle, External Electric Power, Aircraft, 115/200 Volt, 400 Hertz J1349 2004 Engine Power Test Code

(Application for copies should be addressed to SAE, Inc., 400 Commonwealth Drive, Warrendale PA 15096, www.sae.org.)

Underwriters Laboratories, INC. (UL)

UL 489 2006 Molded Case Circuit Breakers & Circuit Breaker Enclosures

(Application for copies should be addressed to UL, 333 Pfingston Rd, Northbrook IL, 60062- 2096, www.ul.com.)

2.4 Order of precedence. 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.

3.0 REQUIREMENTS

3.1 General. The GPU shall be a stand alone, trailer mounted, self-contained unit capable of providing aircraft quality external ground power. Specifically, the GPU shall be capable of providing continuous three phase 72 kW/90kVA of 115/200 VAC (reconnectable to 230/400 VAC) at 400 Hz, and 17 kW of 28 VDC, and 72 kW of 270 VDC electrical power; power is not required to be available simultaneously. The GPU shall be constructed of modular and easily replaceable subassemblies and components wherever possible. The GPU enclosure shall be suitable for full time outdoor use and be 4 wheel trailer mounted. The enclosure shall have doors to provide access for maintenance, repair, and replacement of modular components and subassemblies. Components of the GPU shall be UL recognized or listed whenever possible.

Additional features and capabilities shall be permitted unless otherwise prohibited by this document.

3.1.1 First Article. When specified (see 6.2), two first article GPUs shall be subjected to first article verification in accordance with 4.1.

3.2 Generator/alternator design. The generator shall be of a brushless design; excitation shall be supplied from a brushless exciter as well. Single or double bearing type machines are acceptable.

Temperature rise shall be in accordance with limits set forth in NEMA MG-1 for Class F or H insulation; vacuum impregnated epoxy resin shall be used. Temperature rise of bearing(s) shall not exceed 90 degrees Fahrenheit. Insulation resistance shall not be less than 2 mega-ohms in an ambient temperature of 77 degrees Fahrenheit. The generator shall be of the drip-proof guarded type and meet all applicable standards of NEMA MG-1 and MG-2. The generator shall be capable of operation at 125 % rated speed for at least 15 minutes without electrical or mechanical damage. Electrical windings shall have the following dielectric strength (withstand the following 400 Hz voltages applied for one minute):

a. Armature, 1832 volts between phase windings and 1480 volts between phase windings and ground.

b. Field and Exciter Windings, 10 times ceiling voltage but shall not be less than 1500 or more than 3500 volts between windings and ground.

c. Windings Energized by DC Voltages (Control, Starting, Sharing Systems), 500 volts between windings and ground; windings shall be insulated to Class F or H standards using a void free 100% solids epoxy vacuum pressure impregnation process.

d. All others, twice rated voltage plus 1000 volts applied between windings and ground and between windings when applicable.

The GPU generator and excitation systems shall be capable of withstanding for 10 seconds, a single phase line to neutral, single phase line to line, and symmetrical 3 phase fault when a short is applied while operating at rated load. No reduction in dielectric strength to where the above requirements cannot be met are allowed. Short circuit current is defined as not less than 300 percent of rated full load current. The GPU shall be configured such that neither symmetrical nor asymmetrical faults will cause damage.

3.3 Output electrical power. The GPU shall provide the output power characteristics listed below. All output power shall be available individually; there is no simultaneous AC and DC electrical output power requirement and there is no simultaneous DC and DC electrical power output requirement, i.e. no AC/DC requirement at the same time and no DC/DC requirement at the same time.

3.3.1 AC output power requirements. All aircraft AC power shall be derived from the generator itself and shall meet the performance requirements listed below.

3.3.1.1 AC output voltage and frequency. The GPU output voltage shall be three phase, 115/200 VAC reconnectable to 230/400 VAC, regulated to ±1% at all settings from zero to full load, WYE configured with a grounded neutral and the GPU output frequency shall be 400 Hz regulated to ± 0.5% at all loads. The DC component in the output voltage shall not exceed ±0.1 volts and the crest factor shall be 1.31 to 1.51. The GPU shall operate as specified with a Delta or WYE configured load. The GPU shall come preset from the factory for 115/200 VAC output.

3.3.1.2 Output power rating. The GPU shall meet the requirements set forth herein and any additional requirements contained in MIL-STD-704F. The GPU shall have a continuous output power rating of 72kW/90kVA; the GPU shall be capable of providing continuous power into a load with a power factor between 0.8 leading and 0.8 lagging. With the output voltage preset to 115 (L-N) or 230 (L-N) all applicable tolerances stated herein and in MIL-STD-704F, under all load conditions, to include electrical transients shall be met; the GPU shall meet all requirements set forth herein and the requirements of MIL-STD-704F.

3.3.1.3 Output phase sequence. The phase sequence of the GPU output voltage shall be a positive sequence of A-B-C (AB-BC-CA).

3.3.1.4 Phase balance. The output voltage for each phase shall be balanced (within 1%) while the GPU is operating at full load (with 0.8 power factor lagging or leading), no load, or any load in between. For an unbalanced load (as defined herein) the difference between any of the three phase to neutral voltages shall be no greater than 3.5%.

3.3.1.5 Unbalanced loads. The GPU shall be capable of supplying a 15% maximum unbalanced load. The unbalanced load of 15% shall be defined as one the three phases at its full load condition and the remaining two phases at 85% of their full load condition.

3.3.1.6 Line drop compensation. The GPU shall provide the specified voltage at the end of interfacing cable assemblies described as 115 VAC, 260 amp rated 60 foot (ft.) output power cable (SAE AS 90328-34) or equivalent and at the end of a 230 VAC, 130 amp rated 60 ft.

output power cable (SAE AS 21378-15) or equivalent as required by MIL-STD-704F and herein.

Note: the Government shall have final approval authority on cable equivalency. See Statement of Work (SOW) section 3.6.1 for additional information on interfacing cable assemblies. The GPU shall provide a minimum of 10% voltage adjustment through the use of a manual and an automatic adjustment device to compensate for losses in the output power cable. Note: in certain installations the use of a 125 ft. single jacket 115 VAC 260 amp rated cable is required; the line drop compensation circuit shall provide enough adjustment range to overcome line losses in this cable at a full 260 amp load. The GPU shall have a switch to manually select the compensation method. Manual adjustment shall be done away from the normal operator interface either via locked menu, cabinet door, or similar means. If Remote Voltage Sensing (RVS) is used to process inputs for the automatic line drop compensation, the GPU shall automatically revert to local sensing at the output terminals or bussbars if a break in the sensing wire occurs.

3.3.1.7 Phase angle regulation. The displacement angle between adjacent voltages shall be 120 Degrees (± 2 Degrees) for the balanced load and shall be 120 Degrees (± 4 Degrees) for the three phase 15 percent unbalanced load.

3.3.1.8 Amplitude modulation. The GPU (voltage) amplitude modulation shall not exceed 1% for no load to full load conditions.

3.3.1.9 Frequency stability. The GPU frequency regulation shall be independent of the load changes. The frequency stability of the GPU shall be at a minimum ± 0.5% (400Hz) for all load conditions.

3.3.1.10 Output transient recovery. The GPU transient output voltage recovery shall be IAW MIL-STD-704F Figure 3 and the output frequency transient recovery shall be IAW MIL-STD- 704F Figure 5.

3.3.1.11 AC overload/overcurrent. The GPU shall open the output contactor when the output current exceeds 125% (+/- 2%) on any phase for more than 30 seconds. Overload capacity between 100 and 125% shall be based on the inverse time delay curve principle.

3.3.1.12 Short circuit. The GPU shall be protected against a short circuit across the output AC cable and shall disconnect power from the load buss within 50 milliseconds in the event of a short circuit in any output phase.

3.3.1.13 Total harmonic distortion (THD). The THD in the output voltage for the GPU, regardless of ancillary power supplies, motors, etc that may be operating, shall be as follows:

a. Balanced Load Condition: THD shall not exceed 3% line-to-line and line-to-neutral.

Maximum single harmonic distortion shall not exceed 2% of the fundamental at the nominal voltage.

b. Unbalanced Load Condition: THD shall not exceed 4% line-to-neutral with a 15% unbalanced load applied.

3.3.1.14 AC power cable. Each GPU shall be shipped from the contractor facility with one 115 VAC 260 amp rated capacity, 60 ft., extra flexible, single jacket cable assembly featuring a molded cable head with strain relief and replaceable nose section. If remote voltage sensing is utilized in the line drop compensation method of the GPU control system the cable shall also be equipped with sensing wires. Further, the cable shall be equipped with E/F sensing lines; these lines shall not be "jumpered" at the cable head. The cables shall be part number JB8817-60 (with RVS) CAGE 0SMN2, or JB8816-60NJ (without RVS) CAGE 0SMN2, or equivalent; note that the Government shall have final approval authority on cable equivalency. See SOW section 3.6.1 for additional information on interfacing cable assemblies. Production GPU's are not required to ship with the 230 VAC cable.

3.3.2 DC output power requirements. DC Power Supplies: The 28 and 270 VDC power supplies/converters shall be all solid-state designs using the latest technology for the generation and control of the DC power output. The DC power supplies/converters shall utilize methods to obtain an efficiency of at least 90% at full load conditions and at least 85% at half load conditions. The DC power supplies/converters shall be an integral part of the GPU and designed for continuous outdoor use. The converters shall be air-cooled and shall be designed for easy access, so that any necessary adjustments, part replacements, cable connections, and controls can be accessed through the cabinet/enclosure of the GPU through maintenance panels or doors. All DC power supply/converter inputs shall be from the GPU AC generator output. Each DC power supply/converter shall be equipped with input surge protection to protect the solid-state components from damage due to any unexpected input transient voltages. Each DC power supply/converter shall be designed to place less than 5% input Total Harmonic Distortion (THD) on the AC generator over the entire output load range of the DC power supplies/converters, unless the design approach is such that greater than 5% THD will not negatively affect AC generation system (AC alternator windings). The DC power supplies/converters shall be equipped with soft-start circuitry on the respective internal DC buses to limit inrush current to less than 110% of the power supply/converter input current at full-load output. The soft-start circuitry shall automatically charge the power supply/converter internal DC bus upon application of AC power to the converter. The DC power supplies/converters shall also be equipped with a thermal protection system to prevent damage incurred by overheating.

3.3.2.1 28VDC requirements.

3.3.2.1.1 Output voltage. The 28 VDC Power Supply output voltage shall be 28.5 VDC (nominal). The output voltage shall be adjustable ±10% to compensate for output cable losses but shall be regulated to ±1% (at the cart) at all settings from zero to full load. The 28.5 VDC performance requirements specified herein shall be met when operating with the worst-case combination of 115VAC input line conditions and worst-loads specified herein, and when used with the interfacing cable assembly described as 28 VDC 60ft. output power cable (SAE AS 90347-22) or equivalent. Note: the Government shall have final approval authority on cable equivalency. See SOW section 3.6.1 for additional information on interfacing cable assemblies.

Production GPU's are not required to ship with the 28.5 VDC cable. The 28.5 VDC power supply is not required to be active when the GPU is reconnected to provide 230/400 VAC, 400 Hz output or 270 VDC output.

3.3.2.1.2 Output power rating. The DC Power Supply shall be capable of providing 600 continuous amps of 28.5 VDC electrical power into a load. Additionally the DC Power Supply shall be capable of providing 2000 amps for 30 seconds every 30 minutes for use in starting aircraft. Duty cycle/time on/power availability shall be appropriately reduced at amperages exceeding 600; see 3.3.2.1.6 herein. Additionally, the voltage is allowed to drop below the 28.5 VDC steady state limits when amperages exceeding 600 are provided, however, in no instance shall the voltage ever drop below 12 VDC, which is the starting voltage lower limit of MIL-

STD-704F.

3.3.2.1.3 Ripple voltage. Ripple voltage on the DC Power Supply output voltage shall not exceed

1.5 volts (peak to peak) for no load to full load condition.

3.3.2.1.4 Transient output voltage. The DC Power Supply transient output voltage recovery shall be IAW MIL-STD-704F Figure13.

3.3.2.1.5 Distortion factor. The DC Power Supply distortion factor shall be no greater than 0.035.

The DC Power Supply distortion spectrum shall be IAW MIL-STD-704F Figure 15.

3.3.2.1.6 Overload/overcurrent. The DC Power Supply shall open the output contactor if the current exceeds 1500 amps for more than 3 minutes or if the output current exceeds 2000 amps for 35 seconds. Overload capacity between 600 and 2000 amps shall be based on the inverse time delay curve principle with the two points of interest noted above being on the curve.

3.3.2.1.7 Short circuit. The DC Power Supply shall be protected against a short circuit across the output DC cable and shall disconnect power from the load buss within 50 milliseconds in the event of a short circuit. The short circuit protection circuit shall work in conjunction with the overload limits of 3.3.2.1.6, above.

3.3.2.1.8 Current limiting. The DC Power Supply shall have a current limiting device, controlled by an on-off switch, for use with the jet engine starting feature. Current limiting shall be adjustable via potentiometer type device from at least a 750 to 1500 amp range.

3.3.2.2 270 VDC requirements.

3.3.2.2.1 Output voltage. The 270 VDC Power Supply output voltage shall be 270 VDC, precisely controlled to +/- 1% maximum, from no-load to full-load, at the power converter output (output buss of the GPU). The 270 VDC performance requirements specified herein shall be met when operating with the worst-case combination of 115VAC input line conditions and worst-loads specified herein, and when used with the interfacing cable assembly described as 270 VDC 60 ft. output power cable part number 5PTV6002-101, CAGE 81861. See SOW section 3.6.1 for additional information on interfacing cable assemblies. Note: production GPU's are not required to ship with the 270 VDC cable. The 270 VDC power supply is not required to be active when the GPU is reconnected to provide 230/400 VAC, 400 Hz output or 28.5 VDC output.

3.3.2.2.2 Output power rating. The 270 VDC power converter shall be able to continuously provide 267 amps DC (~ 72KW) @ 270VDC Power into a load.

3.3.2.2.3 Output start-up load. The 270 VDC power converter shall operate within the limits specified herein when the following load is applied: 600 microfarads of capacitance in parallel with 35 KW constant power load. Inrush currents at start up may be as high as 2,000 amps resulting from charging the capacitive load specified above.

3.3.2.2.4 Output maximum load. The 270 VDC power converter shall operate within the limits specified herein when the following loads are applied:

a. Constant power load. 0 to 1,000 microfarads of capacitance in parallel with 0 to 72 KW of constant power load.

b. Pulsed load 1. The converter shall support pulsed loads of up to 140 amps (peak to peak) over the frequency range of 50-500 Hz while maintaining ripple voltage within the limits of Table 1 herein, and distortion within the limits of Figure 1 below.

-50

-40

-30

-20

-10

1 10 100 1000 10000 100000 1000000 Frequency (Hz)

D is to rt io n

V ol ta ge

A m pl itu de (d

B fr om v ol t R M

S) Breakpoints Freq (Hz) dB Vrms

1 0 10 0 22 7 700 7 1 k 10 5 k 10 50 k -10 500 k -50

Figure 1: 270 VDC System Distortion Limits (Pulsed Load 1)

c. Pulsed load 2. The converter shall support pulsed loads of up to 70 amps (peak to peak) over the frequency range of 5,000-15,000 Hz while maintaining ripple voltage within the limits of Table 1 herein, and distortion within the limits of Figure 2 below.

-50

-40

-30

-20

-10

1 10 100 1000 10000 100000 1000000 Frequency (Hz)

D is to rt io n

V ol ta ge

A m pl itu de (d

B fr om v ol t R M

S) Breakpoints Freq (Hz) dB

Vrms 1 0 10 0 22 7 700 7 1 k 10 15 k 10 50 k 0 500 k 40

Figure 2: 270 VDC System Distortion Limits (Pulsed Load 2)

The 50-500 Hz and 5,000-15,000 Hz pulsed loads will not occur simultaneously. The 50- 500 Hz load will have a steady-state load of at least 22 KW during pulsing. The 5,000- 15,000 Hz load will not have any additional steady-state load during the periods of pulsing.

Characteristics Limits

270 VDC

System

270 VDC

System w/Pulsed Load

270 VDC

System w/Pulsed Load

Ripple Amplitude 3 Vpk-avg 9.5 Vpk-avg 15 Vpk-avg Distortion Spectrum Figure 1 Figure 1 Figure 2 Distortion Factor 0.005 max 0.015 max 0.025 max

Table 1: Normal Operating Characteristics

3.3.2.2.5 Output load fault. The 270 VDC converter shall survive load current spikes of up to 3,000 amps without damage.

3.3.2.2.6 Ripple voltage. Output voltage ripple amplitude for the 267 amp 270 VDC output shall be as defined in Table 1 herein.

3.3.2.2.7 Transient output voltage. The 270 VDC output shall remain within the range of 220 to 330 VDC under the worst-case combination of any 115 VAC input voltage step change and under any load step change within the range of 267-0-267 amps DC. The 270 VDC output shall begin recovery from the worst-case transient excursion within 10 milliseconds and shall be recovered to within the steady-state operating range specified herein within 40 milliseconds.

3.3.2.2.8 Distortion factor. The 270 VDC distortion spectrum shall meet the requirements of Figures 1 and 2 herein under the load conditions specified. The 270 VDC distortion factor shall meet the requirements of Table 1 herein under the load conditions specified.

3.3.2.2.9 Overload/overcurrent. The 270 VDC Power Supply/Converter shall have output short circuit protection to remove output power if the load current exceeds 110% of rated load for 150 milliseconds. The power supply shall not be tripped or sustain damage if the load current is between 100 and 110% for a minimum of thirty minutes.

3.3.2.2.10 Short circuit. The 270 DC Power Supply shall be protected against a short circuit across the output cable and shall disconnect power from the load buss within 50 milliseconds in the event of a short circuit.

3.3.2.2.11 Line drop compensation. The 270 VDC power converter shall incorporate an Electronic Line Drop Compensation (ELDC) function on the main 270 VDC output. The ELDC shall be able to adjust the voltage at a point remote from the 270 VDC power converter, effectively canceling out the voltage drop in the 270 VDC output cable. The ELDC shall be settable for a correction at full load from 0 to 4 VDC of the nominal 270 VDC output. This adjustment shall be done away from the normal operator interface either via locked menu, cabinet door, or similar means.

3.3.2.2.12 Cable interlock. The 270 VDC power supply/converter shall be equipped with a cable interlock, similar in nature to a conventional E/F interlock, to prevent power from being applied to the output cable when the cable is not connected to a load. There shall be no control or switch to activate the interlock for the 270; if the 270 VDC power supply is activated so shall the interlock power supply. Upon application of the 270 VDC contactor close device the 28 VDC interlock shall provide the required 28 VDC signal to the load via pin “1” on the cable; following an interval of at least 100 milliseconds the 270 power supply shall activate and provide 270 VDC to the load. At any time if the 28 VDC signal is removed from pin “2” the 270 VDC contactor shall open, removing power from the aircraft and cable. The interlock shall be powered by a nominal 28 VDC power supply capable of providing 10 amps of power. The 28 VDC interlock output shall provide 28 VDC +/- 1 VDC (at the cart) under the worst-case combination of 115 VAC input line and load variation from no-load to full-load, and the 115 VAC steady-state input voltage limits defined in Mil-Std-704F, Table I. Output ripple amplitude for the 10 amp, 28 VDC interlock output shall be as defined in Mil-Std-704F, Table IV. The 28 VDC interlock output shall remain within range of 22 to 40 VDC under the worst-case combination of any 115 VAC input voltage step change and under any load step change from 10-0-10 amps DC. The 28 VDC interlock output shall begin recovery from their worst-case transient within 10 milliseconds and shall be recovered to within the steady-state operating range specified herein within 75 milliseconds. Note: the 270 VDC and the 28VDC interlock returns are required to only be tied together on the aircraft side of the on-aircraft external power receptacle to avoid 270VDC and 28VDC load interconnection problems.

3.4 Reserved.

3.5. Engine system. The engine and related equipment shall be in accordance with Appendix A except as otherwise specified herein. The net power output rating of the engine, when operated on JP-8 fuel at 5,000 feet elevation at 125 degrees F and determined in accordance with SAE J1349, shall be adequate for all performance requirements specified herein. Note: the engine may spend extended amounts of time at both full load and part (low) load conditions. Engine and associated fuel curve ratios/calibrations shall be selected so that part load (10-20 % of full load) conditions do not induce excessive amounts of fuel being injected into the engine, promoting "wet-stacking" issues.

3.5.1 Engine exhaust emissions. The engine shall be a diesel that is certified to comply with the Environmental Protection Agency (EPA) off-highway emission requirements at the time contract award/design. Engine shall be certified by manufacturer to operate on fuels listed herein. Engine shall meet all EPA exhaust emissions requirements while operating with EPA test fuel.

3.5.2 Engine starting. The engine of the GPU shall start at and above 0 degrees F with no external assistance. External starting assistance is allowed from -1 to -25 degrees F. The engine is required to operate, but not start at -26 to -40 degrees F. The engine shall start within 30 (+/- 10%) seconds for a +32 degree F ambient condition. In colder ambient operating ranges of the GPU, the engine shall start with a maximum of three attempts, each attempt shall not exceed 30 (+/- 10%) seconds in duration (to avoid starter overheating and battery drain issues). Internal cyclic starting aids such as air intake heaters, glow plugs, etc may be utilized at temperatures at or above 0 degrees F, or as required by engine manufacturer. Ether based starting aids shall not be used in any temperature range. A combination of installed and external aids such as heat from a winterization type system may be utilized at temperatures from -1 degrees F down to -25 degrees F. The winterization system may include heaters for engine coolant, engine oil, fuel tank, battery warmers, etc. The winterization system shall be designed to operate from an external single phase 120 VAC 60 Hz power source. Note: the winterization system may be powered via use of one or two 15 or 20 amp three wire, polarized, straight blade, non-twistlock, recessed male plugs, (NEMA 5-15R/5-20R style, recessed, reference NEMA WD 6) depending upon engine manufacturer and contractors cold start power requirements. Winterization plugs shall be provided in the lower portion of the control panel and be equipped with weather-proof spring-loaded (in the closed position) covers. Note: circuit breakers and ground fault protection for the winterization system is not required. The winterization system shall incorporate high-temperature shutoff switches to prevent overheating of any fluid or component.

3.5.3 Engine cooling system. The GPU engine cooling system be in accordance with Appendix A.3.3.3 and shall also be designed to allow the GPU to operate safely and reliably in any ambient temperature specified herein at rated power output level. The engine cooling system shall neither draw nor exhaust air beneath the GPU, nor shall the cooling system air intake be located near the engine exhaust system outlet. Note: the use of "push" or "pull" type cooling fan systems is allowed; however, the discharge air shall not be directed at the ground. The engine radiator/fan shall be equipped with guards to prevent injury from the rotating cooling fan. Additionally a coolant recovery system shall be provided on the GPU to prevent loss of coolant fluids.

3.5.4 Engine air intake system. The engine air intake system shall be in accordance with Appendix A.3.3.4 and shall include a primary replaceable dry element and a secondary dry element. Replacement of the primary element shall be accomplished in less than five minutes without the use of special tools or removal of the secondary element. The inlet shall not draw air from beneath the GPU and shall not be located near the cooling system air outlet nor the engine exhaust outlet. Joints shall be minimized between the air filter outlet and the actual engine air inlet and shall be designed to ensure no leakage of unfiltered air into the engine. A differential pressure air filter service indicator shall be provided.

3.5.5 Engine lubrication system. The GPU engine lubrication system shall be in accordance with Appendix A.3.3.5 and shall be designed so that the GPU can be operated on a ± 8 degrees slope in any direction.

3.5.6 Fuels. The GPU engine shall start and operate satisfactorily on all of the fuels listed with no additional additives required: JP-8, JP-5, DF-1, DL-1, LS-1, DS-1, DF-2, DL-2, LS-2, DS-2, and

TS-1 with JP-8 additives, with Jet A, and A1, as secondary fuels. JP-8 shall be the primary fuel used. See Appendix A.3.3.6.1 for further information on the required fuels.

3.5.7 Fuel tank. The GPU shall be equipped with a fuel tank (day tank) sized to contain sufficient fuel to provide at least eight hours of usable fuel for continuous operation at full load. The tank shall be in accordance with Appendix A.3.3.6.7. The tank shall be provided with corrosion protection and baffles. The tank shall be designed so that the GPU can be operated on a ± 8 degrees slope in any direction. A drain valve shall be provided for emptying fuel and sediment into a container outside the GPU without removal of the tank or any other major component. The fuel cap shall be equipped with a retention device to prevent loss and Foreign Object Damage

(FOD).

3.5.8 Exhaust system. The exhaust system shall include a muffler, necessary pipes, and fittings to discharge the exhaust gases to the exterior of the GPU. The exhaust system shall be in accordance with Appendix A.3.3.7. Exhaust system outlet(s) shall be directed upward, away from personnel accessing the control panel or any enclosure doors, the towbar, the engine air intake and the cooling system air intake, and shall not be directed toward the ground. The design of the exhaust system outlet(s) shall preclude the entry of rain.

3.5.9 Governing system. The governing system shall govern the GPU and maintain the specified performance modes at all environmental conditions and on the fuels specified herein. At the specified environmental, temperature, and altitude conditions specified herein, the governing system shall maintain the engine speed within the frequency limits.

3.5.10 Starting system. The GPU shall be equipped with an electric starter powered by the onboard battery(ies).

3.5.11 Battery system. The GPU shall be equipped with a 12 volt DC battery system. The battery(ies) used shall be of a sealed, maintenance free, non-liquid (gel-type) design, and feature top posts for mounting of the battery cables.

3.6 Control and monitoring. The GPU shall be designed to control, indicate, monitor, alarm, and display the functions listed below. All switches and controls shall be located together in a common control panel unless otherwise noted. All displays, controls, and switches shall be of a design such that they can be operated during the use of artic clothing/mittens or chemical, biological, and radiological clothing/rubber gloves. The GPU control panel shall be arranged so that groups of controls are placed in order of similarity. There shall be as a minimum: System Controls, AC Power Instruments and Controls, 28 VDC Power Instruments and Controls, 270 VDC Power Instruments and Controls, Engine System Instruments and Controls, and Fault System Instruments and Controls groupings. Each group of controls shall be clearly marked/delineated to avoid confusion on the groupings. Note: meters may be any type of digital or analog but any selected meter shall meet the accuracy standards herein and meet the operational/non-operational environmental requirements stated herein. The control panel shall be vertically hinged so that components comprising the panel and components behind the panel may be able to be serviced. Multi-function type displays are not expressly prohibited but all parameters for each power type in operation shall be displayed simultaneously (i.e. if AC power is active all parameters listed herein such as volts, amps, frequency shall be displayed simultaneously without the need to toggle between individual screens or menus). Individual type meters for electrical power parameters shall be at least 3.5 inches in diameter; individual type meters for engine parameters shall be at least 2.25 inches in diameter.

3.6.1 System controls.

3.6.1.1 Illumination. The GPU control panel shall be arranged and adequately illuminated so that all controls, switches, and displays may be operated in any ambient lighting condition to include bright sunlight and darkness. Panel illumination shall be able to be controlled via an on-off switch or menu. All displays, LEDs, meters, etc shall be viewable in bright sunlight conditions as typically encountered in an outdoor, flightline, or ramp environment.

3.6.1.2 Emergency stop push-button. An emergency stop push-button shall be provided on the control panel to immediately open the output contactor, turn off the control functions, and stop the engine-activation of the emergency stop device shall immediately turn off the GPU.

3.6.1.3 Electrical output contactors. The GPU shall be equipped with devices for opening and closing the AC, 28.5 VDC, and 270 VDC outputs. All electrical output control devices shall be located on the control panel of the GPU. All devices operating at 400 Hz shall be derated for 400 Hz operation. The 400 Hz AC contactor and the 270 VDC contactors shall be interlocked with their respective 28 VDC safety interlock circuits (see 3.3.2.2.12 and 3.7.1 herein). The contactors shall be tripped by GPU abnormal alarm conditions; power shall be removed from the output contactors within 25 milliseconds after receiving a stop command, fault command, or loss of interlock. The 270 VDC output contactors shall be rated at 300 amps continuous and for make/ break operation into a 1,000 microfarads capacitance. The output contactors do not have to be located on the control panel, but the devices to operate the contactors shall be located on the control panel.

3.6.1.4 Built-in-test-equipment. The GPU shall be provided with Built-in-Test-Equipment (BITE) which will monitor both primary engine and generator circuits and protective circuits for the unit. When a malfunction is detected, the BITE shall inhibit the GPU from operation and activate the fault indication system. The BITE shall perform a complete system self-test prior to start-up through the “Master” switch. An illuminated “Power On” indicator shall indicate all systems are functional and battery power is available to the engine and control circuits. The BITE shall detect all malfunctions that caused the GPU to fail to operate under its normal conditions. All the controls needed to operate or perform manual functions for the Built-in-Test- Equipment features shall be included on the control panel.

3.6.1.5 Master switch. The GPU shall be equipped with a Master switch that will apply and remove battery power to the GPU control systems, panel lights, and fault circuits. Placing the Master switch in the “on” position shall not start the engine but placing the switch in the “off” position shall completely shut down the engine and all other systems/circuits/lights that are functioning at such time.

3.6.1.6 Voltage selector switch. The GPU shall be equipped with a switch or device to select AC voltage, 28 VDC voltage, or 270 VDC voltage.

3.6.2 Fault system instruments and controls. The GPU fault system shall work in conjunction with the BITE system described by 3.6.1.4 herein.

3.6.2.1 System alarm. A lamp(s) or LED(s) to indicate that fault conditions exist shall be provided on the GPU control panel. This indication shall be latched in the ON position during alarm/fault conditions and shall remain ON until the alarm reset push-button is pressed. The GPU shall be capable of detecting and displaying as a minimum the conditions listed in 3.7 herein.

3.6.2.2 Push-to-test device. A push-to-test button or switch shall be provided to test the indicating lamps, light emitting diodes, and display panel for the GPU.

3.6.2.3 Reset device. The GPU shall be provided with a device to reset or clear all alarm or test failure indications. This device shall not prevent a fault from being displayed again if it is still valid.

3.6.3 AC controls.

3.6.3.1 Voltmeter. A voltmeter shall be provided to monitor AC volts. The AC voltmeter shall also have a selector switch to select phase voltages. The meter shall indicate the entire operating range of the GPU with a minimum accuracy of +/- 3%.

3.6.3.2 Ammeter. An ammeter shall be provided to monitor AC amps. The AC ammeter shall also have a selector switch to select phase currents. The meter shall indicate the entire operating range of the GPU with a minimum accuracy of +/- 3%.

3.6.3.3 Frequency meter. A meter shall be provided to indicate the output frequency of the GPU.

The meter shall have a minimum range of 390-410 Hz with enough accuracy to work in conjunction with speed/frequency fine adjustment device in section 3.6.7.8 herein.

3.6.3.4 Contactor control. The GPU shall be equipped with a control device to open and close the output contactor.

3.6.3.5 Contactor closed indicator. The GPU shall be equipped with a device to indicate the output contactor is closed.

3.6.3.6 Voltage sensing. The GPU shall be equipped with a device to manually select local or remote sensing for AC power automatic line drop compensation. This device shall be located away from the normal operator interface via locked menu, cabinet door, or other similar means.

3.6.3.7. Auxiliary receptacle control. The GPU shall be equipped with a device(s) to control the 260 amp rated auxiliary receptacle as described in 3.10.4.3 herein. These controls do not have to be located on the control panel.

3.6.4 28.5 VDC controls.

3.6.4.1 Voltmeter. A voltmeter shall be provided to monitor 28.5 volts. The meter shall indicate the entire operating range of the GPU with a minimum accuracy of +/- 3%.

3.6.4.2 Ammeter. An ammeter shall be provided to monitor 28.5 VDC amps. The meter shall indicate the entire operating range of the GPU with a minimum accuracy of +/- 3%.

3.6.4.3 Contactor control. The GPU shall be equipped with a control device to open and close the

3.6.4.4 Contactor closed indicator. The GPU shall be equipped with a device to indicate the

3.6.4.5 Current limiting control. The GPU shall be equipped with a device to activate/deactivate and a device to adjust the range of the current limiting function of the 28 VDC power supply/converter when the aircraft starting function is used.

3.6.4.6 Voltage trim device. The GPU shall be equipped with a device to adjust the output DC voltage +/- 10% per section 3.3.2.1.1. This device shall be located away from the normal operator interface via locked menu, cabinet door, or other similar means.

3.6.5 270 VDC controls.

3.6.5.1 Voltmeter. A voltmeter shall be provided to monitor 270 volts. The meter shall indicate the entire operating range of the GPU with a minimum accuracy of +/- 3%.

3.6.5.2 Ammeter. An ammeter shall be provided to monitor 28 VDC amps. The meter shall indicate the entire operating range of the GPU with a minimum accuracy of +/- 3%.

3.6.5.3 Contactor control. The GPU shall be equipped with a control device to open and close the

3.6.5.3 Contactor closed indicator. The GPU shall be equipped with a device to indicate the

3.6.6 Reserved.

3.6.7 Engine controls.

3.6.7.1 Elapsed time meter. An elapsed time meter to show the operating hours of the GPU with a range of 99,999 Hours shall be provided.

3.6.7.2 Engine oil pressure. A lubricating oil pressure gauge shall be provided to indicate the pressure of the engine lubricating oil.

3.6.7.3 Engine coolant temperature. A coolant temperature gauge shall be provided to indicate the temperature of the engine coolant.

3.6.7.4 Engine charging system indicator. A voltmeter or ammeter shall be provided to indicate state of charge/discharge of the batteries.

3.6.7.5 Engine fuel gauge. The GPU shall be equipped with a fuel gauge with graduations to show a representation of the amount of fuel remaining in the fuel tank(s).

3.6.7.6 Engine start switch. The GPU shall be equipped with a spring loaded toggle type switch to crank and start the engine. This device shall only operate when the Master switch is in the “on” position.

3.6.7.7 Engine run switch. The GPU shall be equipped with a device to select the engine speed.

The selections shall be marked as "IDLE" and "RUN". These speeds shall be based upon engine manufacturer and contractors design. This device shall not provide an adjustment of the idle or run speed, merely a selection between the two pre-set speeds. This device shall only operate when the Master switch is in the “on” position.

3.6.7.8 Frequency adjust. The GPU shall be equipped with a device to adjust the engine speed.

The device shall provide for a “fine” adjustment of approximately 1 to 2 Hz at a time. This device shall be located away from the normal operator interface via locked menu, cabinet door, or other similar means.

3.7 Safety characteristics. The GPU shall be designed so that all engine and electrical components are enclosed and access is not required during normal operation. Further, the GPU shall be designed to safely permit access to internal components that may be required during troubleshooting for failures or other special needs. All exposed parts that are a hazard to personnel shall be insulated, enclosed, or guarded without impairing the function of the parts.

The GPU design shall not contain any system safety mishap risk categories greater than medium as defined in Table A-IV of MIL-STD-882D. The GPU shall have as a minimum the safety characteristics/protective circuits listed below.

3.7.1 28 VDC aircraft interlock E/F circuit. The GPU shall have a selector switch (located on the control panel) labeled as GPU LOOP-BYPASS-AIRCRAFT LOOP to control the E-F pin interlock circuits. Note: two switches with one labeled as “Generator Power-Aircraft Power” and the other labeled as “Load bank” are also acceptable. The GPU shall contain terminal block points for the connection of 12 AWG wires from the aircraft cable assemblies for the interlock circuit. The GPU E-F interlock circuit shall not be sensitive to the polarity of the DC current flowing to and from the aircraft. When the DC current goes to 0, for any reason, the output contactor in operation shall open within 50 milliseconds. The GPU shall accept an unfiltered half-wave rectified 28 VDC signal, but an intermittent signal shall not be permitted. For descriptive purposes below the “28 VDC signal” below is the nominal steady state value, actual values may range from 16 to 32 volts with 28 +2/-4 volts being the most common steady state values. In “Aircraft Loop” mode, before the interlock loop is complete the voltage sent to the GPU may be a very choppy sine-wave like waveform approaching 60 volts. The GPU shall be capable of receiving and providing at least 2 Amperes of current continuous, and as much as 10 Amperes to close the E/F pin relay contacts.

In the Aircraft Loop mode, the GPU shall close the output contactor for a period of 4 to 6 seconds at start up. The GPU shall receive a 28 VDC signal from the aircraft on the F pin and loop it back to the aircraft via the E pin. This loop shall be monitored by the GPU to determine if a 16 to 32 VDC signal is present. When present, the output contactor shall remain closed. When this signal is not present or drops out the output contactor shall open (within 50 milliseconds).

In the Bypass mode the E-F pins may be connected together but are not monitored or grounded.

The E-F pin circuit is not used to control the output contactor. Any changes required to operate in the Bypass mode shall be automatically implemented.

In the GPU Loop mode, the GPU shall close the output contactor for a period of 4 to 6 seconds at start up. The GPU shall provide a filtered and regulated 28 VDC signal to the aircraft via pin E.

If the 28VDC signal is looped back on the F pin, then the output contactor shall remain closed.

If the voltage is not present on pin F, then the output contactor shall open (within 50 milliseconds).

3.7.2 AC output under/over voltage protective circuit. The output Undervoltage and Overvoltage protective circuit shall trip and alarm the GPU when the voltage is out of the specified range.

Output voltage limits of the GPU shall be: undervolts 108 VAC for 115/200 VAC and 204 VAC for 230/400 VAC for 3 seconds; overvolts 132 VAC for 115/200 VAC and 264 for 230/400 VAC for 1 second. These limits shall be adjustable (via a locked menu or inside enclosure-away from normal operator interface), but preset at the factory to above limits.

3.7.3 28 VDC output under/over voltage protective circuit. The output Undervoltage and Overvoltage protective circuit shall trip and alarm the GPU when the voltage is out of the specified range. Output voltage limits of the GPU shall be IAW MIL-STD-704F: undervolts 20 VDC for 3 seconds; overvolts 32 VDC for 1 second. These limits shall be adjustable (via a locked menu or inside enclosure-away from normal operator interface), but preset at the factory to above limits.

3.7.4 270 VDC output under/over voltage protective circuit. The 270 VDC power converter shall have an output overvoltage protection function set to remove output power if the output voltage exceeds 330 VDC. The 270 VDC power converter shall have an output undervoltage protection function set to remove output power if the output voltage drops below 260 VDC for 40 milliseconds. The 270 VDC power converter shall have an output inverse time delay overvoltage protection function to remove output power before the limits of MIL-STD-704F, Figure 16 are exceeded. The 270 VDC power converter shall have an under-voltage protection function set to shut down the converter if the output voltage drops below the limits of MIL-STD-704F, Figure 16 with its lower curve shifted 10 volts higher. These limits shall be adjustable (via a locked menu or inside enclosure-away from normal operator interface), but preset at the factory to above limits.

3.7.5 DC power supply input protective circuit. The 28.5 VDC and 270 VDC power supplies/ converters shall have an input under/over-voltage protection function set to shut down the converters if the input voltage rises above or falls below the level required to sustain power converter operation within the requirements specified herein.

3.7.6 Output frequency protective circuit. The GPU shall trip and alarm if the steady state output frequency drops below 390 Hz for one second or when the steady state frequency exceeds 410 Hz for one second.