-
M3765/1201
W h e re Do I Find Everything I Need for P rocess Measurement
and Control?
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User’s Guide
DBX, DBQ, DBA, DBBHigh-Accuracy Decade Box
Shop online at
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i
Contents
Contents
.................................................................................................
iWARNING
...............................................................................................
iiCAUTION................................................................................................
iiChapter 1
INTRODUCTION
..........................................................................
1Chapter 2
SPECIFICATIONS
.........................................................................
2Chapter 3
OPERATION
...................................................................................
53.1 Initial Inspection and Setup
.................................................... 53.2.
Connection
............................................................................
5
3.2.1 General Considerations
................................................. 53.2.2 Electrical
Considerations ...............................................
53.2.3 Four-Wire Kelvin Lead Connections
............................. 53.2.4 Thermal emf Considerations
......................................... 63.3 Dial Setting
.......................................................................
6
3.4 Environmental Conditions
...................................................... 6Chapter
4
MAINTENANCE
............................................................................
74.1 Verification of Performance
................................................... 7
4.1.1 Calibration Interval
........................................................ 74.1.2
General Considerations
................................................. 74.1.3 Procedure
......................................................................
7
4.2 Schematic
..............................................................................
7
FiguresFigure 1.1 DBX Series High-Accuracy Decade Box
.............................. 1Figure 2.1 Typical Operating Guide
Affixed to Unit ................................. 4Figure 3.1
Optimal 4-Wire Kelvin Lead Connection
................................. 6Figure 4.1 DBX Series Schematic
Diagram ............................................ 8
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ii
WARNING
OBSERVE ALL SAFETY RULES‘WHEN WORKING WITH HIGH VOLTAGES OR LINE
VOLTAGES.
ELECTRICAL SHOCK HAZARD. DO NOT OPEN CASE.REFER SERVICING TO
QUALIFIED PERSONNEL.
HIGH VOLTAGE MAY BE PRESENT WITH HIGH VOLTAGE OPTIONS.
WHENEVER HAZARDOUS VOLTAGES (> 45 V) ARE USED, TAKE ALL
MEASURES TOAVOID ACCIDENTAL CONTACT WITH ANY LIVE COMPONENTS:
- USE MAXIMUM INSULATION AND MINIMIZE THE USE OF
BARECONDUCTORS.
REMOVE POWER WHEN HANDLING UNIT.
POST WARNING SIGNS AND KEEP PERSONNEL SAFELY AWAY.
CAUTION
DO NOT APPLY ANY VOLTAGES OR CURRENTS TO THE TERMINALS OF
THISINSTRUMENT IN EXCESS OF THE MAXIMUM LIMITS INDICATED ON
THE FRONT PANEL OR THE OPERATING GUIDE LABEL.
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1INTRODUCTION
Chapter 1
INTRODUCTION
The Omega DB series of resistance decade boxesis a family of
instruments providing a very broad choiceof high-performance
resistance sources. Any num-ber of decades from one to eleven is
available in achoice of accuracies.
The Omega DB decade box is a precision resis-tance source with
excellent characteristics of stabil-ity, temperature coefficient,
power coefficient, andfrequency response.
The Omega DB Series employs very-low-resistanceswitches with
silver alloy contacts. A special designkeeps zero resistance to
less than 1 mΩ per decade.Self cleaning keeps the silver contacts
from becom-ing tarnished when unused, or when only low cur-rents
are passed through them. This is most often thecase when only
minute test currents are drawn bydigital multimeters or other test
instruments. Contactresistance is stable and remains low and
repeatable.
High-quality gold-plated tellurium-copper binding postsserve to
minimize the thermal emf effects which wouldartificially reflect a
change in dc resistance measure-ments. All other conductors within
the instrument, aswell as the solder employed, contain no metals or
junc-
tions that could contribute to thermal emf problems.
The standard models offer a choice of one througheleven decades.
The panels are clearly labeled show-ing the step size and maximum
voltage and currentlimitations for each decade.
With a resolution as low as 1 mΩ and a maximumavailable
resistance of over 111 MΩ, the Omega DBseries may be used for
exacting precision measure-ment applications requiring high
accuracy, good sta-bility, and low zero-resistance. They can be
used ascomponents of dc and ac bridges, for calibration, astransfer
standards, and as RTD simulators.
The Omega DB Series may be rack-mounted toserve as components in
measurement and control sys-tems.
Figure 1.1. DBX Series High Accuracy Decade Box
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2 SPECIFICATION
Chapter 2
SPECIFICATIONS
For convenience to the user, the pertinent specifications are
given in an OPERATING GUIDE affixedto the case of the instrument.
Figure 2.1 shows a typical example.
Accuracy: After subtraction of zero resistance, at
23°C;traceable to NIST.
DBX: ±(0.01% + 2 mΩ)
DBA: ±(0.05% + 2 mΩ)
DBQ: ±(0.02% + 2 mΩ)
Zero Resistance:
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3SPECIFICATION
Total Res.(ΩΩΩΩΩ)
No. ofDecades
Model*(0.01% Accuracy)
DBX-1-0.001 0.01 1 0.001DBX-1-0.01 0.1 1 0.01DBX-1-0.1 1 1
0.1DBX-1-1 10 1 1DBX-1-10 100 1 10DBX-1-100 1 k 1 100DBX-1-1K 10 k
1 1 kDBX-1-10K 100 k 1 10 kDBX-1-100K 1 M 1 100 kDBX-1-1M 10 M 1 1
MDBX-1-10M 100 M 1 10 MDBX-2-0.001 0.11 2 0.001DBX-2-0.01 1.1 2
0.01DBX-2-0.1 11 2 0.1DBX-2-1 110 2 1DBX-2-10 1.1 k 2 10DBX-2-100
11 k 2 100DBX-2-1K 110 k 2 1 kDBX-2-10K 1.1 M 2 10 kDBX-2-100K 11 M
2 100 kDBX-2-1M 110 M 2 1 MDBX-3-0.001 1.11 3 0.001DBX-3-0.01 11.1
3 0.01DBX-3-0.1 111 3 0.1DBX-3-1 1.11 k 3 1DBX-3-10 11.1 k 3
10DBX-3-100 111 k 3 100DBX-3-1K 1.11 M 3 1 kDBX-3-10K 11.1 M 3 10
kDBX-3-100K 111 M 3 100 kDBX-4-0.001 11.11 4 0.001DBX-4-0.01 111.1
4 0.01DBX-4-0.1 1.111 k 4 0.1DBX-4-1 11.11 k 4 1
Resolution(ΩΩΩΩΩ)
Single Decade DBX Unit
SINGLE DECADE UNITS
ORDERING INFORMATION
Single-decade units are available withresistance as low as 1 mΩ
per step toas high as 10 MΩ per step. These unitssatisfy many
system applications re-quiring only a single decade
whilemaintaining all the quality features ofthe DB series.
Each decade is enclosed in an alumi-num case which can serve as
a shield.
It may be panel mounted and inte-grated with additional units to
formpotentiometer circuits or other con-figurations.
Each unit consists of low-inductanceresistors in series, with a
high-perfor-mance solid-silver-alloy-contactswitch.
* For less exacting applications, more economical tolerances are
available:- For 0.02% accuracy substitute DBQ in part number in
lieu of DBX- For 0.05% accuracy substitute DBA in part number in
lieu of DBX- For 0.1% accuracy substitute DBB in part number in
lieu of DBX
OPTIONS- RM Rack mountable case for standard 19" rack- K Kelvin
type 4-terminal binding posts- RO Rear output binding posts
DBX-4-10 111.1 k 4 10DBX-4-100 1.111 M 4 100DBX-4-1K 11.11 M 4 1
kDBX-4-10K 111.1 M 4 10 kDBX-5-0.001 111.11 5 0.001DBX-5-0.01
1.1111 k 5 0.01DBX-5-0.1 11.111 k 5 0.1DBX-5-1 111.11 k 5 1DBX-5-10
1.1111 M 5 10DBX-5-100 11.111 M 5 100DBX-5-1K 111.11 M 5 1
kDBX-6-0.001 1.111 11 k 6 0.001DBX-6-0.01 11.1111 k 6 0.01DBX-6-0.1
111.111 k 6 0.1DBX-6-1 1.111 11 M 6 1DBX-6-10 11.1111 M 6
10DBX-6-100 111.111 M 6 100DBX-7-0.001 11.111 11 k 7
0.001DBX-7-0.01 111.1111 k 7 0.01DBX-7-0.1 1.111 111 M 7 0.1DBX-7-1
11.111 11 M 7 1DBX-7-10 111.1111 M 7 10DBX-8-0.001 111.111 11 k 8
0.001DBX-8-0.01 1.111 111 1 M 8 0.01DBX-8-0.1 11.111 111 M 8
0.1DBX-8-1 111.111 11 M 8 1DBX-9-0.001 1.111 111 11 M 9
0.001DBX-9-0.01 11.111 111 1 M 9 0.01DBX-9-0.1 111.111 111 M 9
0.1DBX-10-0.001 11.111 111 11 M 10 0.001DBX-10-0.01 111.111 111 1 M
10 0.01DBX-11-0.001 111.111 111 11 M 11 0.001
Total Res.(ΩΩΩΩΩ )
No. ofDecades
Model*(0.01% Accuracy)
Resolution(ΩΩΩΩΩ )
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4S
PE
CIF
ICA
TIO
N
CONSULT INSTRUCTION MANUAL FOR PROPER INSTRUMENT OPERATIONDBX
SERIES HIGH ACCURACY DECADE BOX
Temperature Coefficient:
-
5OPERATION
Chapter 3
OPERATION3.2.2 Electrical Considerations
In order to make proper use of the full performancecapabilities
of the DBX unit, especially if low resis-tance or low-resistance
increments are important,care must be taken in connecting to the
terminals ofthe decade box.
In particular, in order to keep contact resistance toa minimum,
the most substantial and secure connec-tion to the binding posts
should be made. They ac-cept banana plugs, telephone tips, spade
lugs, alli-gator clips, and bare wire. The largest or
heaviestmating connection should be made, and, where ap-plicable,
the binding posts should be securely tight-ened.
These considerations may be relaxed wheneversingle milliohms are
considered significant for the taskbeing performed.
3.2.3 Four-Wire Kelvin Lead Connections
Whenever possible, 4-wire Kelvin leads, the idealconnection,
should be employed. Such a connec-tion minimizes the effects of
contact resistance andapproaches ideal performance.
If the four terminals are available as clamps similarto
alligator clips, they may be connected to the necksof the binding
posts. If the four terminals are avail-able separately, the optimal
connection is shown inFigure 3.1, where the current leads are
introducedinto the top of the binding posts, and the voltageleads
at the necks.
3.1 Initial Inspection and Setup
This instrument was carefully inspected before ship-ment. It
should be in proper electrical andmechanical order upon
receipt.
An OPERATING GUIDE is attached to the caseof the instrument to
provide ready reference to speci-fications.
3.2 Connection
3.2.1 General Considerations
The DBX Series Decade unit provides three termi-nals labeled H
(high), L (low), and G (ground). TheH and L terminals are connected
to the ends of theresistance being set; the G terminal is connected
tothe case. The G terminal may be used as a guard orshield
terminal. It may also be connected (using ashorting link) to either
terminal to allow two-termi-nal as opposed to three-terminal
measurements.
In order to make the most stable measurements,determine which is
the more sensitive of the two userleads, i.e. the one going into a
higher impedance.This lead should be connected to the more
protectedone of the two DBX terminals. That would eitherbe the DBX
terminal that is shorted to the case, orthe LOW DBX terminal
whenever neither is con-nected to the case.
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6 OPERATION
3.2.4 Thermal emf Considerations
The highest-quality low-ernf components are usedin the DBX
Series. There nevertheless may be someminute thermal emf generated
at the test leads wherethey contact the gold banana jacks.
This emf will not reflect itself if an ac measurementinstrument
is employed. It will also be eliminated if ameter with so called
“True Ohm” capability is used.Otherwise it may represent itself as
a false compo-nent of the dc resistance measurement.
3.3 Dial Setting
Whenever the dials are used in positions 0-9, theresulting
resistance is simply read directly. Both thedecimal point and the
steps are clearly marked onthe panel.
For additional flexibility and range, each decade pro-vides a
“10” position setting. This “10” position onany one decade equals
the “1” position on the nexthigher decade. It adds about 11% to the
nominaltotal decade resistance.
To determine the resistance obtained when one ormore “10”
settings are used, simply add “1” to thenext higher decade. For
example, a setting of3-6-10-0-10 Ω becomes:
3 3 0 0 0 06 6 0 0 0
10 1 0 0 00 0 0
10 1 0 ____________________________
TOT 3 7 0 1 0
and a setting of 10-10-10-l0-10.10 Ωbecomes:
10 1 0 0 0 0 0.010 1 0 0 0 0.010 1 0 0 0.010 1 0 0.010 1 0.0
.10 1.0 ________________________________
TOT 1 1 1 1 1 1.0
3.4 Environmental Conditions
For optimal accuracy, the decade box should be usedin an
environment of 23oC. It should be allowed tostabilize at that
temperature after any significant tem-perature variation.
Humidity should be maintained at laboratory condi-tions. This is
especially important if high resistancesare involved.
Figure 3.1 Optimal 4-Wire Kelvin Lead Connection
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7MAINTENANCE
Chapter 4
MAINTENANCE
4.1 Verification of Performance
4.1.1 Calibration Interval
The DB Series instruments should be verified forperformance at a
calibration interval of twelve (12)months. This procedure may be
carried out by theuser if a calibration capability is available, by
Omega,or by a certified calibration laboratory.
If the user should choose to perform this procedure,then the
considerations below should be observed.
4.1.2 General Considerations
It is important, whenever testing the DBX SeriesDecade Units, to
be very aware of the capabilitiesand limitations of the test
instruments used. A resis-tance bridge may be employed, and there
are di-rect-reading resistance meters or digital
multimetersavailable that can verify the accuracy of these
units,especially when used in conjunction with standardsthat can
serve to confirm or improve the accuracyof the testing
instrument
Such test instruments must be significantly more ac-curate than
±(l00ppm+2 mΩ) for all applicableranges, allowing for a band of
uncertainty of the in-strument itself. A number of commercial
bridges andmeters exist that can perform this task;
consultOmega.
It is important to allow both the testing instrumentand the DBX
Substituter to stabilize for a numberof hours at the nominal
operating temperature of23OC, and at nominal laboratory conditions
of hu-midity. There should be no temperature gradientsacross the
unit under test.
Substantial Kelvin type 4-wire test terminals shouldbe used to
obtain accurate low-resistance readings.It is convenient, once the
zero resistance has beendetermined, to subtract it from the
remaining mea-surements. This can be automatically done in
manyinstruments which have an offset subtraction capa-bility.
4.1.3 Procedure
1. Confirm the zero resistance of the unit.2. Determine the
allowable upper and lower
limits for each resistance setting of each decadefollowing the
specified accuracy. For theDBX series, these limits for any
resistance“R” are [R±(0.0001 R + 2 mΩ)]. For the A,B, or Q series,
see specifications.
3. Confirm that the resistances fall within theselimits after
subtraction of the zero resistance.
4. If any resistances fall outside these limits, theassociated
switch assembly may requirereplacement.
4.2 SchematicRefer to Figure 4.1 for a schematic of the DB
de-cade unit.
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8 MAINTENANCE
Figure 4.1. DB Series Schematic Diagram
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Servicing North America:USA: One Omega Drive, P.O. Box 4047ISO
9001 Certified Stamford CT 06907-0047
TEL: (203) 359-1660 FAX: (203) 359-7700e-mail:
[email protected]
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777 6622Toll Free in United Kingdom: 0800-488-488e-mail:
[email protected]
WARRANTY/DISCLAIMEROMEGA ENGINEERING, INC. warrants this unit to
be free of defects in materials and workmanship for aperiod of 25
months from date of purchase. OMEGA’s WARRANTY adds an additional
one (1) monthgrace period to the normal two (2) year product
warranty to cover handling and shipping time. Thisensures that
OMEGA’s customers receive maximum coverage on each product. If the
unit malfunctions, it must be returned to the factory for
evaluation. O M E G A’s Customer ServiceDepartment will issue an
Authorized Return (AR) number immediately upon phone or written
request.Upon examination by OMEGA, if the unit is found to be
defective, it will be repaired or replaced at nocharge. O M E G A’s
WARRANTY does not apply to defects resulting from any action of the
purchaser,including but not limited to mishandling, improper
interfacing, operation outside of design limits, improper repair,
or unauthorized modification. This WARRANTY is VOID if the unit
shows evidence of having been tampered with or shows evidence of
having been damaged as a result of excessive corrosion;or current,
heat, moisture or vibration; improper specification;
misapplication; misuse or other operatingconditions outside of O M
E G A’s control. Components which wear are not warranted, including
but not limited to contact points, fuses, and triacs.OMEGA is
pleased to offer suggestions on the use of its various products.
However, OMEGA neither assumes responsibility for any omissions or
errors nor assumes liability for anydamages that result from the
use of its products in accordance with information provided
byOMEGA, either verbal or written. OMEGA warrants only that the
parts manufactured by it will beas specified and free of defects.
OMEGA MAKES NO OTHER WARRANTIES OR R E P R E S E N TATIONS OF ANY
KIND WHATSOEVER, EXPRESS OR IMPLIED, EXCEPT THAT OF TITLE,AND ALL
IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY AND
FITNESS FOR A PA RTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION
OF L I A B I L I T Y: The remedies of purchaser set forth herein
are exclusive, and the total liability of OMEGA with respect to
this order, whether based on contract, warranty, negligence,
indemnification, strict liability or otherwise, shall not exceed
the purchase price of the component upon which liability is based.
In no event shall OMEGA be liable for consequential, incidental or
special damages.CONDITIONS: Equipment sold by OMEGA is not intended
to be used, nor shall it be used: (1) as a “BasicComponent” under
10 CFR 21 (NRC), used in or with any nuclear installation or
activity; or (2) in medicalapplications or used on humans. Should
any Product(s) be used in or with any nuclear installation ora c t
i v i t y, medical application, used on humans, or misused in any
way, OMEGA assumes no responsibilityas set forth in our basic WA R
R A N TY/ DISCLAIMER language, and, additionally, purchaser will
indemnifyOMEGA and hold OMEGA harmless from any liability or damage
whatsoever arising out of the use of theProduct(s) in such a
manner.
RETURN REQUESTS/INQUIRIESDirect all warranty and repair
requests/inquiries to the OMEGA Customer Service Department.
BEFORERETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN
AUTHORIZED RETURN(AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPA
RTMENT (IN ORDER TO AV O I DPROCESSING DELAYS). The assigned AR
number should then be marked on the outside of the returnpackage
and on any correspondence.The purchaser is responsible for shipping
charges, freight, insurance and proper packaging to preventbreakage
in transit.
FOR WARRANTY RETURNS, please have the following information
available BEFORE contacting OMEGA:1 . Purchase Order number under
which the product
was PURCHASED,2. Model and serial number of the product
under
warranty, and3. Repair instructions and/or specific problems
relative to the product.
FOR NON-WARRANTY REPAIRS, consult OMEGAfor current repair
charges. Have the followinginformation available BEFORE contacting
OMEGA:1. Purchase Order number to cover the COST
of the repair,2. Model and serial number of the product, and3.
Repair instructions and/or specific problems
relative to the product.
OMEGA’s policy is to make running changes, not model changes,
whenever an improvement is possible. This affordsour customers the
latest in technology and engineering.OMEGA is a registered
trademark of OMEGA ENGINEERING, INC.© Copyright 2001 OMEGA
ENGINEERING, INC. All rights reserved. This document may not be
copied, photocopied,reproduced, translated, or reduced to any
electronic medium or machine-readable form, in whole or in part,
without theprior written consent of OMEGA ENGINEERING, INC.
OMEGAnet® Online Service Internet e-mailw w w.omega.com i n f o
@ o m e g a . c o m
It is the policy of OMEGA to comply with all worldwide safety
and EMC/EMI regulations thatapply. OMEGA is constantly pursuing
certification of its products to the European New
ApproachDirectives. OMEGA will add the CE mark to every appropriate
device upon certification.The information contained in this
document is believed to be correct, but OMEGA Engineering, Inc.
accepts no liability for any errors it contains, and reserves the
right to alter specifications without notice.WARNING: These
products are not designed for use in, and should not be used for,
patient-connected applications.
Omega im bk 02-02.pdfContentsContents iCAUTION Chapter 1Chapter
2 SPECIFICATIONS Chapter 33.1 Initial Inspection and Setup 53.2.1
General Considerations 5 3.2.2 Electrical Considerations 3.4
Environmental Conditions 6Chapter 4 4.1.1 Calibration Interval
4.1.3 Procedure 4.2 Schematic