scope:

This specification covers the general requirements for accurate, wire-wound, fixed resistors that have a maximum resistance tolerance of 1 percent, and a high degree of stability with respect to time under specified environmental conditions. The resistors are suitable for continuous full-load (or voltage) operation at any ambient temperature up to 125°C, and when derated, up to 145°C (see 6.5). They are not suitable for applications where the alternating current (ac) characteristics are of critical importance. They will have life failure rates (FR) ranging from 1.0 to 0.001 percent per 1,000 hours (see 1.2.1.5). These failure rates are established at 60-percent confidence level on the basis of the life tests. The failure rate, identified by the appropriate symbol, is referred to operation at full rated voltage and temperature. A part per million (PPM) quality system is used for documenting and reporting the average outgoing quality of resistors supplied to this specification. Statistical process control (SPC) techniques are required in the manufacturing process to minimize variation in production of resistors supplied to the requirements of this specification.

The PIN shall be in the following form, and as specified (see 3.1 and 6.1):

The style is identified by the three letter symbol "RBR" followed by a two digit number; the letters identify established reliability, accurate, wire-wound, fixed resistors, and the number identifies the size and power rating of the resistors. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: U.S. Army Laboratory Command, ATTN: SLCET-R-S, Fort Monmouth, NJ 07703-5000 by using the self-addressed Standardization Document Improvement at the end of this document or by letter.

The terminal is identified by a single letter in accordance with table I. TABLE I. Terminal.

Symbol Terminal -------------------------- L Solderable U Weldable

The nominal resistance is expressed in absolute ohms (1 absolute ohm = 0.99951 international ohm) and is identified by five digits; the first four digits represent significant figures and the last digit specifies the number of zeros to follow. When the values of resistance are less than 1,000 ohms, or when fractional values of an ohm are required, the letter "R" is substituted for one of the significant digits to represent the decimal point. When the letter "R" is used, succeeding digits of the group represent significant figures. The resistance value designations are shown in table II. Minimum and maximum resistance values shall be as specified (see 3.1). The standard values for every decade shall follow the sequence demonstrated for "10 to 100" decade in table III. The resistance values for 0.01-percent (T), 0.02-percent (Q), 0.05-percent (A) and 0.1-percent (B) resistance tolerances may be of any value within the limits of this specification, but it is preferred that the values be chosen from the 192-series decade specified in table III. Except for the 0.01-percent (T), 0.02-percent (Q), 0.05-percent (A), and 0.1-percent (B) resistance tolerances, resistance values not listed shall be considered as not conforming to the specification.

For nonstandard values in resistance tolerances A, B, Q, and T, the designation of resistance shall be the actual ohmic value (see 3.26.2). When fractional values of an ohm are required the decimal point shall be used. TABLE II. Designation of resistance values.

Designation Resistance value (ohms) ---------------------------------------------------------------------------------------------------- R1000 to R9880 incl. 0.100 to 0.9880 incl. 1R000 to 9R880 incl. 1.000 to 9.8800 incl. 10R00 to 98R80 incl. 10.000 to 98.8000 incl. 100R0 to 988R0 incl. 100.000 to 988.0000 incl. 10000 to 98800 incl. 1,000 to 9,880 incl. 10001 to 98801 incl. 10,000 to 98,800 incl. 10002 to 98802 incl. 100,000 to 988,000 incl. 10003 to 98803 incl. 1,000,000 to 9,880,000 incl.

The initial resistance tolerance is identified by a single letter in accordance with table IV. TABLE IV. Initial resistance tolerance and applicable minimum resistance values.

Symbol Initial resistance Minimum tolerance resistance values (at 25°C ±2°C) (see 3.1) ---------------------------------------------------------------- Percent (+) Ohms T 0.01 10 Q 0.02 10 A 0.05 10 B 0.10 10 F 1.00 0.10

The life failure rate designation as shown in table V is signified by a single letter (M, P, R, S), which identifies the life failure rate level for which the resistor is qualified (see 4.5 and 6.3). TABLE V. Life failure rate level (established at 60-percent confidence).

Failure rate Failure rate level designation percent/1,000 hours ----------------------------------------- M 1.0 P 0.1 R 0.01 S 0.001

intended Use:

These resistors are designed for use in DC amplifiers, voltmeter multipliers, electronic computers, meters and laboratory test equipment.