1 - PD Resistance Transfer Standard 26E-009A-DC.pdf

P.D. 26E-009A-DC,

12/18/2025

Rev #3

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PURCHASE DESCRIPTION

for

RESISTANCE TRANSFER STANDARD

1.0 SCOPE: This purchase description (PD) describes a Resistance Transfer Standard which is a collection of six (6) boxes of precision resistors containing nominal values ranging from 1 ohm to 100 kilo-ohms. Each box shall consist of 12 precision resistors connected in series of the same nominal value. Each resistor shall feature four terminal (Kelvin) connections, allowing for accurate individual measurements or configurable series and parallel combinations. This box shall be accompanied by accessories that allow the unit to be connected into series-parallel connections. This was achieved in legacy devices by using passive connectors, similar to the Series- Parallel Connector (SPC102), Parallel Compensation Network (PC101), and shorting bar (SB103). These accessories allowed metrology grade repeatability, low hysteresis, and low impedance connections within a Resistor Transfer Standard, as well as effectively eliminate connection errors when performing four-terminal measurements. The unit shall have enhanced thermal stability, reduced temperature-induced measurement errors, and power dissipation characteristics as described in this PD.

Each resistance transfer standard box shall be uniform in design and intended for similar applications. To further enhance temperature stability, units with resistance values below 100 kΩ shall be oil-filled and hermetically sealed. This product line is designed to replace legacy models including the ESI SR1010, TEGAM SR1010, IET SR1010, SR1030, and SR1060.

2.0 FUNCTIONAL REQUIREMENTS: All items that contain specifications that are equal to or better than all of the specifications stated below, will be evaluated for acceptability.

2.1 Resistance values: Each resistance transfer standard shall consist of six (6) resistor boxes. In each box, there shall be twelve (12) individual precision resistors connected in series, all of the same nominal value: 1 Ω, 10 Ω, 100 Ω, 1 kΩ 10 kΩ, and 100 kΩ.

2.2 Nominal resistance tolerance: For the above identified resistors, they shall have a maximum of the below uncertainty.

Value ±PPM Initial Adjustment: resistors matched to within 10 ppm 1 Ω - 100 kΩ ≤ 20 for 6 months:

1 Ω - 100 kΩ ≤ 35 for 2 years:

1 Ω - 100 kΩ ≤ 50 for 5 years:

2.3 Calibration Uncertainty (k=2): 1 Ω – 100 kΩ ≤ 10 ppm

(Four-terminal measurement, at 10 mW for 1Ω - 100 kΩ)

2.3.1 Transfer Accuracy:

• 100:1 ± (1 ppm + 1 µΩ) at parallel value, legacy device used the SB103, PC101, and SP102 to achieve this transfer accuracy.

• 10:1 ± (1 ppm + 0.1 µΩ) at parallel value, legacy device used the SB103, PC101, and SP102 to achieve this transfer accuracy.

2.4 Stability:

2.4.1 30 Day Stability: 1 Ω – 100 k Ω 10 ppm

2.4.2 180 Day Stability: 1 Ω – 100 k Ω 10 ppm

2.4.3 12 Month Stability: 1 Ω– 100 k Ω 20 ppm

2.5 Temperature Coefficient: Value ±PPM/°C

1 Ω ± 15 ppm/ºC matched within 5 ppm/ºC 10 Ω ± 1 ppm/ºC 100 to 100 k Ω ± 5 ppm/ºC matched within 5 ppm/ºC

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2.6 Power Coefficient: Value ±PPM/mW

(1 mW to 10 mW) 1 Ω ±0.3

10 Ω ±0.02 100 Ω – 100 kΩ ±0.1

2.7 Maximum Current and Voltage Capabilities:

SR1030 Resistance Value Per Step

One Resistor Alone Maximum I, 10 Resistors in Parallel (R/10)

Maximum I, V

10 Resistors in Series (R10)

Maximum I, V

1 Ω 1.0 A, 1.0 V 7.07 A, 707 mV 707 mA, 7.07 V 10 Ω 316 mA, 3.16 V 2.23 A, 2.23 V 223 mA, 22.3 V

100 Ω 100 mA, 10 V 707 mA, 7.07 V 70.7 mA, 70.7 V 1 kΩ 31.6 mA, 31.6 V 223 mA, 22.3 V 22.3 mA, 233 V

10 kΩ 10 mA, 100 V 70.7 mA, 70.7 V 7.07 mA, 707 V

* Based on the breakdown voltage of 1500 volts peak to case

2.8 Calibration: The units delivered shall be fully calibrated by comparison to external standards traceable to the National Institute of Standards and Technology (NIST) or equivalence. Any unique hardware and software accessories required for calibration of this item, to the specifications of this purchase description and to its published specification, shall be furnished by the manufacturer.

3.0 MECHANICAL & PHYSICAL REQUIREMENTS:

3.1 Configuration: As described in section 2.1, each resistor box shall consist of a single housing containing at least twelve (12) separate resistors connected in series. The unit’s resistors shall have terminals as described in this PD and shall have the ability to be connected into series-parallel connections.

This was achieved in legacy devices by using passive connectors, similar to the Series-Parallel Connector (SPC102), Parallel Compensation Network (PC101), and shorting bar (SB103). These accessories allowed metrology grade repeatability, low hysteresis, and low impedance connections within a Resistor Transfer Standard, as well as effectively eliminate connection errors when performing four-terminal measurements.

AFMETCAL has observed the use of active switches has introduced measurement errors.

3.2 Output connections: The resistor output connections shall be four-wire configuration consisting of insulated binding posts that will accept single or dual banana plugs, spade lugs or wire. The construction should be of tellurium copper (or equivalent) for low thermal EMF and low resistance. The spacing between the Current and the Potential pair of jacks shall be standard 0.75 inch spacing. All resistor connectors shall be permanently labeled and the resistance by the four associated connections.

3.3 Other connection: The unit shall include ground connections. These shall be insulated binding posts that accept banana plugs, spade lugs or wire.

3.4 Weight: The weight of each resistor box shall not exceed 6.8 kg (15 lbs). The collection of six (6) shall not exceed 40.82 kg (90 lbs).

3.5 Dimensions: The dimensions of each resistor box shall not exceed the following: Height 152 mm (6 in), Width 152 mm (6 in), Depth 381 mm (15 in).

3.6 Oil Immersion Provides Thermal Isolation: All standards, except the 100 kΩ/step standard, are immersed in a mineral oil bath. Oil immersion provides thermal isolation to minimize the effects of ambient temperature variations. The oil speeds the dissipation of heat created in the resistors during calibration. This heat dissipation further contributes to the stability of the standards. Oil Bath type is mineral oil, like Penreco Drakeal #9. With insulation resistance of typically 1014 Ohms.

3.7 Gasket Seal: Gaskets seal resistor to keep the work surface and measuring contacts clean. The gaskets also minimize oil aging and contamination to lengthen the time between oil changes.

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3.8 Operating Environment: All purchase description specifications shall be met when the unit is used within this operating environment range. The instrument shall perform to all specifications within the following environment:

3.8.1 Temperature Range: 22.8ºC ± 3.3 ºC (73 ±6 ºF).

3.8.2 Humidity Range: 20% to 50% relative humidity RH

3.8.3 Storage Environment: Damage to the unit shall not occur as a result of storage in the following environment:

3.8.3.1 Temperature Range: 0ºC to 50ºC ( 32ºF to 126ºF)

3.8.3.2 Humidity Range: 15% to 80% relative humidity RH

3.9 Resistor Quality: All resistors provided shall be aged so that when delivered all meet or exceed specifications in section. All resistors shall be manufactured from materials having excellent stability, and an extremely low temperature coefficient / power coefficient.

3.10 Marking: All resistors shall have a label with the following as a minimum marking: Nominal Value, Temperature Range, Maximum Voltage, Maximum Current and Temperature Coefficient (if not in a temperature-controlled environment).

3.11 Design: All resistors shall be designed to minimize insulation leakage errors and resistance variations due to ambient temperature changes, mechanical shock encountered in normal handling, and the application of normal voltages, currents and operating power. These items shall be designed and constructed of material that meet the requirements of this specification and in accordance with the best commercial practices for industry approved equipment. It will be the contractors responsibility to assure the Government that such design objectives as reliability, accuracy of operation, maintainability, and ease of operation have been given due consideration in the manufacture of this equipment. The equipment shall be able to withstand the conditions met in shipping, storage, installation and service. All material and parts for this equipment shall be capable of withstanding the environmental requirements of this specification.

These items shall be constructed in such a way that the resistors are not required to be operated in an external temperature stabilized oil bath or external oil-filled environment.

3.12 Terminals: Citing historical performance and maintenance of Air Force owned oil-filled resistance transfer standards, the vendor shall guarantee the binding post and insulator materials used in the terminals to have successful oil containment performance for the full planned lifecycle of the unit, which is twenty

(20) years.

3.13 Conformance to Purchase Description: The manufacturer shall deliver products that meet the salient characteristics of this purchase description and conform to the producer’s own commercial drawings, specifications, standards, and quality assurance practices.

3.14 Portability: The accuracy and stability shall not be altered from normal handling and transportation of the resistors.

3.15 Shipment Orientation: Damage or accuracy deterioration to the resistors shall not result due to normal shipment of the unit.

3.16 Commercial Air Transportability: The resistors shall be suitable for commercial air transport and shall meet all regulations that apply.

4.0 ENVIRONMENT, SAFETY, AND OPERATIONAL HEALTH: A combination of the system manual, other documentation, and/or the system itself shall identify potential environment, safety and operational health hazards and how they are mitigated when the design itself cannot mitigate them.

This will be accomplished through stating the hazard and accompanying mitigation through the use of safety devices, use of warnings, or use of special operational procedures to counter such hazards.

5.0 TESTING: The item will be inspected and accepted at a destination specified elsewhere in this contract. The item will be checked with test equipment and parameters equal to or better than those required assuring specified performance requirements are met. Test equipment has first echelon

Page #4 of 5 certification directly traceable to the International System of Units through the National Institute of Standards and Technology (NIST) or other AFMETCAL approved sources where required. Tests will be performed to assure the item meets or exceeds all of the requirements of this purchase description. Such testing does not relieve the contractor of performing all inspections and quality control checks at the point of fabrication as necessary to assure performance as specified.

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Attachment to Purchase Description

26E-009A-DC

Resistance Transfer Standard

DATA REQUIREMENTS

MANUALS: A complete user and service manual and calibration procedure shall be provided with each unit in contractor format. Manuals shall be on CD/DVD-ROM in Indexed Portable Document Format (iPDF). The manuals shall comply with Data Item Description (DID) DI-TMSS-80527D and the Contract Data Requirements List (DD Form 1423).

CALIBRATION CERTIFICATE: A calibration certificate, traceable to the National Institute of Standards and Technology (NIST) or other national metrology institutes (NMIs) shall be provided with each instrument. This calibration certificate must comply with Data Item Description (DID) DI-QCIC- 80798C and the Contract Data Requirements List (DD Form 1423).

FAILURE SUMMARY AND ANALYSIS REPORT: A complete Failure Summary and Analysis Report shall be provided once at the end of every Fiscal Year (once/if warranty repairs begin). The reports shall comply with Data Item Description (DID) DI-SESS-81495C and the Contract Data Requirements List (DD Form 1423).

Commercial Engineering Design Data and Associated Lists: The following shall be provided: a 2-dimensional (2D) engineering drawing in accordance with MIL-STD-31000B paragraph 5.4.1.4. A geometric representation defining the physical shape of the product. The PDF document shall contain:

Nomenclature, Document/Drawing Number, Part Number, Contract Number, Design Activity Identification (e.g. CAGE Code(s)), Approved By, Approved Date, Revision Level Identification, Revision Date, and if applicable Export Control/ITAR Statements, Distribution Statements, Destruction Notices, and/or Classification Requirements.