Omega Products DBA Installation Manual
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MONITORING AND CONTROL
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DBX, DBQ, DBA, DBB
High-Accuracy Decade Box
M3765/1201
Contents
Contents ................................................................................................. i
WARNING ............................................................................................... ii
CAUTION................................................................................................ ii
Chapter 1
INTRODUCTION .......................................................................... 1
Chapter 2
SPECIFICATIONS ......................................................................... 2
Chapter 3
OPERATION ................................................................................... 5
3.1 Initial Inspection and Setup .................................................... 5
3.2. Connection ............................................................................ 5
3.2.1 General Considerations ................................................. 5
3.2.2 Electrical Considerations ............................................... 5
3.2.3 Four-Wire Kelvin Lead Connections ............................. 5
3.2.4 Thermal emf Considerations ......................................... 6
3.3 Dial Setting ....................................................................... 6
3.4 Environmental Conditions ...................................................... 6
Chapter 4
MAINTENANCE............................................................................ 7
4.1 Verification of Performance ................................................... 7
4.1.1 Calibration Interval ........................................................ 7
4.1.2 General Considerations ................................................. 7
4.1.3 Procedure ...................................................................... 7
4.2 Schematic .............................................................................. 7
Figures
Figure 1.1 DBX Series High-Accuracy Decade Box .............................. 1
Figure 2.1 Typical Operating Guide Affixed to Unit ................................. 4
Figure 3.1 Optimal 4-Wire Kelvin Lead Connection................................. 6
Figure 4.1 DBX Series Schematic Diagram ............................................ 8
i
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 TO
AVOID ACCIDENTAL CONTACT WITH ANY LIVE COMPONENTS:
- USE MAXIMUM INSULATION AND MINIMIZE THE USE OF BARE
CONDUCTORS.
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 THIS
INSTRUMENT IN EXCESS OF THE MAXIMUM LIMITS INDICATED ON
THE FRONT PANEL OR THE OPERATING GUIDE LABEL.
ii
Chapter 1
INTRODUCTION
The Omega DB series of resistance decade boxes
is a family of instruments providing a very broad choice
of high-performance resistance sources. Any number of decades from one to eleven is available in a
choice of accuracies.
The Omega DB decade box is a precision resistance source with excellent characteristics of stability, temperature coefficient, power coefficient, and
frequency response.
The Omega DB Series employs very-low-resistance
switches with silver alloy contacts. A special design
keeps zero resistance to less than 1 mΩ per decade.
Self cleaning keeps the silver contacts from becoming tarnished when unused, or when only low currents are passed through them. This is most often the
case when only minute test currents are drawn by
digital multimeters or other test instruments. Contact
resistance is stable and remains low and repeatable.
High-quality gold-plated tellurium-copper binding posts
serve to minimize the thermal emf effects which would
artificially reflect a change in dc resistance measurements. All other conductors within the instrument, as
well 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 through
eleven decades. The panels are clearly labeled showing the step size and maximum voltage and current
limitations for each decade.
With a resolution as low as 1 mΩ and a maximum
available resistance of over 111 MΩ, the Omega DB
series may be used for exacting precision measurement applications requiring high accuracy, good stability, and low zero-resistance. They can be used as
components of dc and ac bridges, for calibration, as
transfer standards, and as RTD simulators.
The Omega DB Series may be rack-mounted to
serve as components in measurement and control systems.
Figure 1.1. DBX Series High Accuracy Decade Box
INTRODUCTION
1
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