PD Resistance Standard Rev 1.pdf

P.D. 25E-009A-DC,

Rev #1

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PURCHASE DESCRIPTION

for

RESISTANCE STANDARD

1.0 SCOPE: This purchase description applies to a resistance standard consisting of six precision resistors with nominal values ranging from 1 ohm to 100 kilo-ohms. Each resistor features four-terminal (Kelvin) connections, allowing for accurate individual measurements or configurable series and parallel combinations. These combinations can be achieved using optional accessories such as the Series-Parallel Connector (SPC102), Parallel Compensation Networks (PC101), and shorting bars (SB103). These features enhance thermal stability, reduce temperature-induced measurement errors, and improve power dissipation characteristics.

The resistance standards are uniform in design and intended for similar applications. To further enhance temperature stability, units with resistance values below 100 kΩ are 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: The six resistors shall consist of the following nominal values: 1 Ω, 10 Ω, 100 , 1 k 10 k, 100 k.

2.2 Nominal resistance tolerance: Value ±PPM

Initial Adjustment: resistors matched to within 10 ppm 1 - 100 k ≤ 20 for 6 months:

1 - 100 k ≤ 35 for 2 years:

1 - 100 k ≤ 50 for 5 years:

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

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

2.3.1 Transfer Accuracy: 100:1 ±(1 ppm + 1 µΩ) at parallel value, using SB103, PC101, and SP102

10:1 ±(1 ppm + 0.1 µΩ) at parallel value, using SB103, PC101, and SP102

2.4 Stability:

2.4.1 30 Day Stability: 1 – 100 k 10 ppm

2.4.2 180 Day Stability: 1 – 100 k 10 ppm

2.4.3 12 Month Stability: 1 – 100 k 20 ppm

2.5 Temperature Coefficient: Value ±PPM/°C

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

2.6 Power Coefficient: Value ±PPM/mW

(1 mW to 10 mW) 1 ±0.3

10 ±0.02 100 – 100 k ±0.1

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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 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.

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

3.3 Weight: The weight of per resistor, weight shall not exceed 6.35 kg ( 10 lbs).

3.4 Dimensions: Height 120 mm (4.7 in) Width 117 mm (4.6 in) Depth 335 mm (13.2 in).

3.5 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.

3.6 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.

3.7 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:

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

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

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

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

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

3.8 Resistor Quality: All resistors provided shall be aged so that when delivered all meet or exceed specifications in par 3.2. All resistors shall be manufactured from materials having excellent stability, and an extremely low temperature coefficient / power coefficient.

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3.9 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).

3.10 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.

3.11 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.

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

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

3.14 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 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.

Attachment:

Data Requirements