Statement of Work (SOW)
International Space Station (ISS) DC / AC Power Inverters
The purpose of this statement of work is to outline the requirements for delivery of 120VDC/120VAC
power inverters for use aboard the International Space Station (ISS). The inverter will be classified as
Criticality III hardware, which means that a single inverter failure will not result in the loss of crew life,
ISS, or the mission.
2.0 Applicable documents
The work performed and products delivered shall conform to the requirements defined in this SOW and in
SSP 50835 Rev B. It should be noted that JSC document #JSC 66171 identifies the SSP 50835 Rev B
requirements which are applicable to the inverter project.
3.0 Data Deliverables
3.1 Acceptance Testing
All acceptance test data shall be documented and delivered to NASA-JSC.
3.2 Parts List Traceability
Lot and serial number traceability of each inverter shall be delivered to NASA-JSC. Lot and serial number
traceability is only required at the top-level assembly, which is the inverter. Lot and serial number
traceability of individual piece parts is not required.
4.0 Design Requirements
Any exposed PVC shall be covered by a high-temperature, nontoxic-gas generating material (i.e Kynar or
4.2 Manufacturing and Assembly
The internal and external contents of each inverter shall be assembled and installed in a manner which
prevents damage or loosening of parts after exposure to vibration in the x, y, and z axes according to the
vibration spectrum defined in SSP 50835 Rev B.
Each inverter shall be designed such that it will perform after exposure to vibration in the x, y, and z axes
according to the vibration spectrum defined in SSP 50835 Rev B.
Each inverter shall provide the following:
4.4.1 120VDC 1100W inverter: a minimum of 700W output power.
4.5.1 Each inverter shall have provisions for thermal management which allow the inverters to meet the
electrical requirements listed in section 4.4 of this SOW without damage.
4.5.2 If provisions for thermal management involve use of a fan, the air intake shall utilize a screen or
guard which will result in compliance with the following requirement: SSP 50835 Rev B 184.108.40.206.
Each inverter shall have a minimum of the following:
1. Four output power receptacles with covers/dust caps
2. Four output power switches
3. Four output power switch guards
4. One input power connector with a cover/dust cap
5. One input power status LED
6. Four output power status LEDs
5.0 Design Changes
The Supplier shall identify any materials, form, or function changes made to or proposed for part numbers
XPK-1-I-6-1 from the time these commercial parts were procured by NASA-JSC.
5.1 Removal of Warning Buzzer
For NASA’s application, the warning buzzer will not provide any benefit. Therefore, the warning buzzer
shall be removed or muted.
6.0 Acceptance Test Requirements
A minimum of the following acceptance tests are required. These tests shall be performed on all inverters
prior to delivery to NASA-JSC.
6.1 Functional performance verification
The flight units shall provide the following:
120VDC: 120VAC output at 60Hz
The flight units shall undergo a minimum 23 hr burn in prior to delivery.
6.3 Fault protection verification
6.3.1 The flight units shall have fault protection from over voltage.
6.3.2 The flight units shall have fault protection from over-current.
6.3.3 The flight units shall have fault protection from over-temperature.
6.3.4 The flight units shall have fault protection from under-voltage.
7.0 Hardware Deliverables
7.1 120V Units
The Supplier shall deliver a quantity of 50 120VDC to 120VAC 1100W ISS Inverters.
8.0 Calibration System
The Supplier shall have a documented calibration system that meets the requirements of American National
Standard Institute (ANSI)/National Conference of Standards Laboratories (NCSL) Z540-1, General
Requirements for Calibration Laboratories and Measuring and Test Equipment.
9.0 Record Retention
Supplier shall maintain verifiable objective evidence of all inspections and test performed, results obtained
and dispositions of non-conforming articles. These records shall be identified to associated articles,
including lot and serial numbers of inverters, and made available to Customer and/or Government
Representatives upon delivery to NASA-JSC.
10.0 Quality Provisions
10.1 Record Retention
The contractor shall maintain a copy of all data produced by this contract for six months after the period of
the performance of this contract. NASA-JSC will maintain those records thereafter.
10.2 Flight Hardware Clause
FOR USE IN HUMAN SPACE FLIGHT; MATERIALS, MANUFACTURING, AND WORKMANSHIP
OF HIGHEST QUALITY STANDARDS ARE ESSENTIAL TO ASTRONAUT SAFETY. IF YOU ARE
ABLE TO SUPPLY THE DESIRED ITEM WITH A HIGHER QUALITY THAN THAT OF THE ITEMS
SPECIFIED OR PROPOSED, YOU ARE REQUESTED TO BRING THIS FACT TO THE IMMEDIATE
ATTENTION OF THE PURCHASER