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SRac Series

Page 1 of 1

ac Standard Resistance

Working Standards

SRac Datasheet March 2020

Features:

• Very stable - <20 ppm/year

• Calibrated at dc and 1 kHz

• Excellent temperature coefficient - as

low as 1 ppm/°C

• < 20 ppm difference between dc and

ac values at 1 kHz for resistances ≤

100 kΩ

• Wide range of values - 1 mΩ to 10 MΩ

• bnc option (-bnc)

• Custom values are available

• Optional transit case

Economical high performance

ac resistance standards

SRAC SERIES

Designed for use as a reference or work-

ing standard in industrial, research, and

educational laboratories.

Model

SRac-

Nominal

(Ω)

Initial

adjustment to

nominal

(ppm)

Stability

1 year

(ppm)

Tempco

(ppm/°C)

Resistor

type

Calibration

uncertainty

dc

(Typical)

(ppm)

dc to ac

change at

1 kHz

(Typical)

(ppm)

Max.

power

(W)

Max.

voltage

(V)

Max.

current

(A)

Terminals

0.001

0.001

200

50

20

Manganin

strip

200

25

0.2

0.015

14

4 bp's + gnd

0.01

0.01

200

50

20

Manganin wire

100

0.6

0.15

4.5

0.1

0.1

100

20

1

Foil

60

0.3

0.17

1.7

1

1

1

10

0.3

0.54

0.54

10

10

2

5

0.6

2.45

0.245

100

100

1

5

24.5

0.024

1K

1 k

1

5

77.5

7.7 mA

10K

10 k

1

2

245

2.5 mA

100K

100 k

1

2

300

2 mA

1M

1 M

5

Wirewound

5

250

0.5

700

0.7 mA

10M

10 M

15

Film

10

2500

0.1

1000

0.1 mA

Foil resistors have a power coefficient of resistance (PCR) of ±5ppm at rated power due to internal heating

Foil resistors have a voltage coefficient (VC) of < 3ppm/V

SPECIFICATIONS

SRac Series Resistance Standard

Calibration conditions:

At 23°C, low power, traceable to the SI through an NMI.

Connections as indicated in table.

Terminals:

Gold plated, tellurium copper, high current, heavy

duty,low thermal-emf binding position standard 3/4 inch

spacing. A case GROUND terminal is provided on all

units.

Dimensions: 8.6 cm H x 10.5 cm W x 12.7 cm D (3.4"

x 4.15" x 5")

Operating temperature range: 15 to 30°C.

Transit case:

Optional Model SRC-100 lightweight transit case

with handle, suitable for transporting and storing

two units. The case provides mechanical protec-

tion and insulation from temperature changes

during transportation or shipping.

Optional Model SRC-100-5

lightweight

transit

case with handle, suitable for transporting and stor-

ing 5 SRC/SRX resistance standards.

bnc option:

Option -bnc changes Hi and Lo binding posts to 4

x bnc connectors plus the ground binding post.

SRC-100-5 Lightweight transit case for 5 standards

Standard model

Select from table above

Custom value

SRX-XXX or SRC-XXX

Transit case for SRac units SRC-100, for 2 units

SRC-100-5, for 5 units

ORDERING INFORMATION

Frequency response

Frequency response of the foil resistors are given

by the formula below:

Options:

-bnc

4 bnc connectors plus ground