Yokogawa 278610 Precision Measuring Instruments

PRECISION MEASURING
INSTRUMENTS

Bulletin 2700-E

SELECTOR GUIDE FOR PRECISION MEASUREING INSTURUMENTS

Classifi cation

Galvanometer

Wheatstone

bridge

Double bridge

Standard

resistor

Model

Number

0.1 1 10 100µV

Measuring Range (Accuracy) Page

2707

2708

0.1 1 10 100mΩ110100

2768 5

2755 6

2752 7

(±0.01 to ±0.05%)

(±0.1 to ±0.6%)

(±0.3%)

110100k

Ω

110100M

Ω

Ω

2769 6

2792A 8

4

Variable resistor

279301

279303

278610

278620

2791

(±0.01%)

(±0.05%)

(±0.05 to ±2%)

(±0.05 to ±0.5%)

10

11

3

2707

2708

Electronic Galvanometer

270710 2708

Galvanometer

4

2768

Precision Wheatstone Bridge

2768

5

2755

2769

Portable Wheatstone Bridge

275597 276910

182×226×128mm 2kg

(7-1/4×9×4-3/4” 4.4lbs)

Portable Double Bridge

182×226×128mm 2.6kg

(7-1/4×9×4-3/4” 5.7lbs)

6

2752

Precision Double Bridge

2752

2753

2754

7

2792A Series

Standard Resistors

• Accuracy 40% higher than our pre vi ous models!
Temp erature c o ef fi cient down 2/3!



Main Features

• Traced to the national standar d for high ac cu ra cy; test
(calibrated) accuracy of ±5 ppm

• Resistance temperature coeffi cient

Excellent temperature characteristics in the range of 0 -50ºC;

resistance temperature coeffi cient less than ±2.5 ppm/ºC

• A variety of models

Eight models with nominal resistance val ues rang ing between

0.001 Ω and 10 k

Ω

• Precision temperature control equipment, such as an oil bath,
not needed for cal i bra tion due to marked im prove ment in
re sis tance temperature coeffi cient

• Included document: Test certifi cate

100

0

-100

0

5

10

15

The 2972A Series of standard resistors are metal foil re sis tors,
while the previous 2972 Series were winding resistors. The
error range of the 2972A Series is much smaller than those of
the previous 2972 Series, as demonstrated by the resistance
tem per a ture coeffi cient curves (Graph 1). Precision temperature
con trol equipment such as oil baths, are not needed for
mea sure ment and calibration. The 2972A can do these in an air
en vi ron ment.

At development sites, the 2972A serves many purposes,
rang ing from precision measurement to calibration of
equip ment. The main body of the 2972A employs the same
plastic case as that of the previous series, and the 2972A has
a damage-resistant and easy-to-connect terminal block. The
2972A can be even more effective in precision measurement
when it is combined with our potentiometer and double bridge.

2792A Series

20

25

30

35

40

-200

-300

Error (ppm)

-400

-500

-600

8

2792 α=-5 to +10 β=Less than -0.7
2792A α=±2.5 β=Less than -0.1

2792 α=-5 2792 α=+10 2792A α=-2.5 2792A α=+2.5

Graph 1 Error characteristics of the 2792 and
2792A Series with respect to temperature

2792 Series

Rt=R20 (1+a (t-20)+b (t-20)2)

Temperature (˚C)

SPECIFICATIONS

Model Nominal value

2792A01 0.001 Ω ±100ppm -5 to ±15 Less than -0.1 ±100 ppm per year 54.7
2792A02 0.01 Ω ±75ppm ±10 Less than -0.1 ±75 ppm per year 17.3
2792A03 0.1 Ω ±50ppm ±5 Less than -0.1 ±50 ppm per year 5.47
2792A04 1 Ω ±30ppm ±2.5 Less than -0.1 ±30 ppm per year 1.73
2792A05 10 Ω ±30ppm ±2.5 Less than -0.1 ±30 ppm per year 0.547
2792A06 100 Ω ±30ppm ±2.5 Less than -0.1 ±30 ppm per year 0.173
2792A07 1 kΩ ±30ppm ±2.5 Less than -0.1 ±30 ppm per year 0.055
2792A08 10 kΩ ±30ppm ±2.5 Less than -0.1 ±30 ppm per year 0.017

Standard test conditions: DC current, temperature: 23 ±2°C, power: below 0.1 W (2792A01) and below 0.01 W (2792A02-2792A08)

Accuracy
23°C±2°C

Temperature

coeffi cient

␣23 (ppm/°C)

Operating temperature and humidity ranges

Temperature

coeffi cient

␤(ppm/°C

2

)

• External Dimensions

Drift per year

: 0-50ºC / 20-80% RH
Storage temperature and humidity ranges
: -20-60ºC / 20-80% RH
Maximum allowable power : 3 W

ø104

150

12525

Test ( c a librat e d ) accuracy : ±5 ppm
Power characteristics : ±100 ppm/W
Insulation resistance : More than 1000 MΩ at 500 V DC
Withstand voltage : 1.5 kV for one minute between
measurement terminal and casing

174 150

Ter m inal construc t ion : 4 terminals
External dimensions : Approximately ø104  150 mm
(current terminal width:

approximately 174 mm)
Weight : Approximately 1.2 kg
Accessories : User’S Manual, One Test Certifi cate

Maximum

allowable current

(A)

Unit: mm

OPERATING PRECAUTIONS

• Temperature

To main t a in a high level o f measurement accuracy, the
Standard Re sis tor must be used in rooms with a constant
ambient tem per a ture or placed in a thermostatic chamber.
Measure the ambient tem per a ture accurately and perform
compensation according to the temperature coeffi cient.
Ensure that the instrument is not subjected to rapid chang es
in temperature during storage as changes in resistance or
deterioration of the insulator may result. (Instrument can be
op er at ed stably for over two hours.)

• Temperature coeffi cients and resistance

The resistance at temperature t is expressed by the following
equa tion:

= R23 {1 + α23(t -23) + β(t -23)2}

R

t

where

: Resistance value at t˚C

R

t

: Resistance value at 23˚C

R

23

: 1st temperature coeffi cient at 23˚C

α

23

: 2nd temperature coeffi cient at 0 to 50˚C

β

• Current

When electric current fl ows through the Standard Resistor, its
re sis tance value changes due to the generated heat. To ensure
accurate measurement, use the Standard Resistor below the
maximum al low able current, which is one of the standard test
conditions. When the applied current exceeds the maximum
allowable current, the re sis tance could change, or the internal
circuit could be broken.

• Thermal emf and Contact Resistance

To minimize the effects of thermal emf, connect the circuit
with cop per wire, and take the average of two readings obtained
by reversing the direction of the current fl owing through the
current terminals. In com plete contact between the lead wire and
the terminals causes current change due to contact resistance,
and temperature errors due to heat generation.

• Mechanical Shock and Vibration

Mechanical shock and vibration may cause distortion of the
resistive elements, which results in instability and changes in the
resistance value.

99

2793

Decade Resistance Boxes

279301

10

2786

2791

Decade Resistance Boxes

2786 2791

Slide Resistors

11

World Wide Web site at

http://www.yokogawa.com/ymi

NOTICE

● Before using the product, read the instruction manual
carefully to ensure proper and safe operation

YOKOGAWA METERS & INSTRUMENTS CORPORATION

International Sales Dept.

YOKOGAWA CORPORATION OF AMERICA

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KOREA CORPORATION

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Subject to change without notice. [Ed: 03/b] Printed in Japan: Aug. 2011(C)/1,000(KP)

All Rights Reserved. Copyright © 1996, Yokogawa Meters & Instruments Corporation.

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