Keithley 5156 User manual

Model 5156 Electrometer Calibration Standard
Instruction Manual
A GREATER MEASURE OF CONFIDENCE

WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material
and workmanship for a period of 1 year from date of shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date
of shipment: probes, cables, rechargeable batteries, diskettes, and documentation.
During the warranty period, we will, at our option, either repair or replace any
product that proves to be defective.
To exercise this warranty, write or call your local Keithley representative, or con-
tact Keithley headquarters in Cleveland, Ohio. You will be given prompt assistance
and return instructions. Send the product, transportation prepaid, to the indicated
service facility. Repairs will be made and the product returned, transportation pre-
paid. Repaired or replaced products are warranted for the balance of the original
warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without
Keithley’s express written consent, or misuse of any product or part. This warranty
also does not apply to fuses, software, non-rechargeable batteries, damage from bat-
tery leakage, or problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED
OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANT-
ABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PRO-
VIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.
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EES SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCI-
DENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF
ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRU-
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BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION,
LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR
DAMAGE TO PROPERTY.
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2/03

Model 5156 Electrometer Calibration Standard
Instruction Manual
01995, Keithley Instruments, Inc.
All rights reserved.
Cleveland, Ohio, U.S.A.
January 1999, Second Printing
Document Number: 5156-901-01 Rev. B

Manual Print History
The print history shown below lists the printing dates of all Revisions and Addenda
created for this manual. The Revision Level letter increases alphabetically as the man-
ual undergoes subsequent updates. Addenda, which are released between Revisions,
contain important change information that the user should incorporate immediately
into the manual. Addenda are numbered sequentially. When a new Revision is cre-
ated, all Addenda associated with the previous Revision of the manual are incorpo-
rated into the new Revision of the manual. Each new Revision includes a revised copy
of this print history page.
Revision A(Document Number 51%YOI-01). ......... December 1994
Addendum A (Document Number 5156-901-02). ....... November 1996
Addendum A (Document Number 5156-901-03). .......... March 1997
Revision B (Document Number 5156-901-01). ........... January 1999

The following safety precautions should be observed before using this product and any asso-
ciated instrumentation. Although some instruments and accessories would normally be used
with non-hazardous voltages, there are situations where hazardous conditions may be present.
This product is intended for use by qualified personnel who recognize shock hazards and are
familiar with the safety precautions required to avoid possible injury. Read and follow all
installation, operation, and maintenance information carefully before using the product. Re-
fer to the manual for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product may
be impaired.
The types of product users are:
Responsible body is the individual or group responsible for the use and maintenance of
equipment, for ensuring that the equipment is operated within its specifications and operat-
ing limits, and for ensuring that operators are adequately trained.
Operators use the product for its intended function. They must be trained in electrical safety
procedures and proper use of the instrument. They must be protected from electric shock and
contact with hazardous live circuits.
Maintenance personnel perform routine procedures on the product to keep it operating
properly, for example, setting the line voltage or replacing consumable materials. Mainte-
nance procedures are described in the manual. The procedures explicitly state if the operator
may perform them. Otherwise, they should be performed only by service personnel.
Service personnel are trained to work on live circuits, and perform safe installations and re-
pairs of products. Only properly trained service personnel may perform installation and ser-
vice procedures.
Keithley products are designed for use with electrical signals that are rated Installation Cat-
egory I and Installation Category II, as described in the International Electrotechnical Com-
mission (IEC) Standard IEC 60664. Most measurement, control, and data I/O signals are
Installation Category I and must not be directly connected to mains voltage or to voltage
sources with high transient over-voltages. Installation Category II connections require pro-
tection for high transient over-voltages often associated with local AC mains connections.
Assume all measurement, control, and data I/O connections are for connection to Category
I sources unless otherwise marked or described in the Manual.
Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on
cable connector jacks or test fixtures. The American National Standards Institute (ANSI)
states that a shock hazard exists when voltage levels greater than 30V RMS, 42.4V peak, or
60VDC are present.
A good safety practice is to expect that hazardous voltage is present
in any unknown circuit before measuring.
Operators of this product must be protected from electric shock at all times. The responsible
body must ensure that operators are prevented access and/or insulated from every connection
point. In some cases, connections must be exposed to potential human contact. Product op-
erators in these circumstances must be trained to protect themselves from the risk of electric
shock. If the circuit is capable of operating at or above 1000 volts,
no conductive part of
the circuit may be exposed.
Do not connect switching cards directly to unlimited power circuits. They are intended to be
used with impedance limited sources. NEVER connect switching cards directly to AC
mains. When connecting sources to switching cards, install protective devices to limit fault
current and voltage to the card.
Before operating an instrument, make sure the line cord is connected to a properly grounded
power receptacle. Inspect the connecting cables, test leads, and jumpers for possible wear,
cracks, or breaks before each use.
Safety Precautions
5/02

When installing equipment where access to the main power cord is restricted, such as rack
mounting, a separate main input power disconnect device must be provided, in close prox-
imity to the equipment and within easy reach of the operator.
For maximum safety, do not touch the product, test cables, or any other instruments while pow-
er is applied to the circuit under test. ALWAYS remove power from the entire test system and
discharge any capacitors before: connecting or disconnecting cables or jumpers, installing or
removing switching cards, or making internal changes, such as installing or removing jumpers.
Do not touch any object that could provide a current path to the common side of the circuit under
test or power line (earth) ground. Always make measurements with dry hands while standing on a
dry, insulated surface capable of withstanding the voltage being measured.
The instrument and accessories must be used in accordance with its specifications and oper-
ating instructions or the safety of the equipment may be impaired.
Do not exceed the maximum signal levels of the instruments and accessories, as defined in
the specifications and operating information, and as shown on the instrument or test fixture
panels, or switching card.
When fuses are used in a product, replace with same type and rating for continued protection
against fire hazard.
Chassis connections must only be used as shield connections for measuring circuits, NOT as
safety earth ground connections.
If you are using a test fixture, keep the lid closed while power is applied to the device under
test. Safe operation requires the use of a lid interlock.
If or is present, connect it to safety earth ground using the wire recommended in the
user documentation.
The symbol on an instrument indicates that the user should refer to the operating in-
structions located in the manual.
The symbol on an instrument shows that it can source or measure 1000 volts or more,
including the combined effect of normal and common mode voltages. Use standard safety
precautions to avoid personal contact with these voltages.
The
WARNING heading in a manual explains dangers that might result in personal injury
or death. Always read the associated information very carefully before performing the indi-
cated procedure.
The
CAUTION heading in a manual explains hazards that could damage the instrument.
Such damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and all test cables.
To maintain protection from electric shock and fire, replacement components in mains cir-
cuits, including the power transformer, test leads, and input jacks, must be purchased from
Keithley Instruments. Standard fuses, with applicable national safety approvals, may be used
if the rating and type are the same. Other components that are not safety related may be pur-
chased from other suppliers as long as they are equivalent to the original component. (Note
that selected parts should be purchased only through Keithley Instruments to maintain accu-
racy and functionality of the product.) If you are unsure about the applicability of a replace-
ment component, call a Keithley Instruments office for information.
To clean an instrument, use a damp cloth or mild, water based cleaner. Clean the exterior of
the instrument only. Do not apply cleaner directly to the instrument or allow liquids to enter
or spill on the instrument. Products that consist of a circuit board with no case or chassis
(e.g., data acquisition board for installation into a computer) should never require cleaning
if handled according to instructions. If the board becomes contaminated and operation is af-
fected, the board should be returned to the factory for proper cleaning/servicing.
!

Specifications
STANDARD SPECIFICATION
Nominal Accuracy of Temperature Voltage Nominal
Value Characterization Coefficient CCWBklellt
Tuleranee
of Standard wm PPmJ°C ppmNolt * %
100 MQ 200 <2s <l 2
I GB 300 <25 <I 2
IO GQ 400 <25 <I 2
100 GQ 500 <IO0 <I 2
I nF IO00 <I20 <5 5
100 nF 1000 <120 4 5
STABILITY (ppm/Yr. Max.)
100 MQ 200
1 GQ 500
IO GR 500
100 GP 800
I nF 1000
100 Ill: 1000
GENERAL
DATA PORT: For downloading of 5156characterized data to 6517 Electrometer.
MAX. INPUT VOLTAGE: 2OOV peak.
CONNECTORS: One 3.Lug Triax for meter, Six BNC’s for Calibrator connection.
ENVIRONMENT:
Operating: 23°C+3-C, 30-60% R.H. non-condensing.
TEMPERATURE STABILIZATION: 4 hours in Environment.
PHYSICAL:
Case Dimensions: 114mm high x 165mm wide x 184mm deep
(4.5 in x 6.5 in x 7.2 in).
Net Weight: <1.7kg (<3.8 lb).
Shipping Weight: <4.lkg (~9 lb).
ACCESSORIES SUPPLIED:
Certificate of Calibration.
Charge Filter.
7078.TRX-3 3-Lug Triax Cable.
8501-l Dala Transfer Cable.
OperatDrs Manual.
Specifications subject to change without notice

Table of Contents
Section 1 - General Information
Introduction
Features
Manual addenda..............
Safety symbols and terms
Specifications.
Unpacking and inspection
Inspection for damage
Handling precautions.
Shipment contents
Documentation.
Repacking for shipment.
Optional accessories
..............
..............
..............
..............
..............
..............
..............
Section 2 - Operation
Introduction .................................
Definition of a standard. .......................
Panel familiarization ..........................
Top panel ..............................
Prontpanel.............................
Charge filter. ................................
Test conslderatmn
..............................
Recommended voltage calibrators. ...............
Current standard operation .....................
Current connections ......................
Current calculations. .....................
‘&pica1 calibrator voltages. ................
Charge standard operation, .....................
Charge connections ......................
Charge calculations ......................
Typical calibrator voltages. ................
...................
5
................... 5
................... 6
................... 6
................... 8
................... 8
................... 9
................... 9
................ ..I 0
................ ..I 0
................ ..I 0
................ ..I 2
................ ..12
................ ..12
................ ..I 4
................ ..I 4

Resistance standard operations ........................
Unguarded operation. ..........................
Guarded operation. ............................
Calibrating/verifying the Model 6517A Electrometer ......
Section 3 - Maintenance
Introduction.
Connector cleaning
Factory characterization
User characterization.
Updating standards values.
Front panel.
IEEE-488 bus
Viewing characterized values
Replaceable parts.
Factory service
Schematic diagram
..........
..........
..........
..........
..........
..........
..........
..........
..........
..........
..........
..........
..........
..........
..........
I9
19
I9
I9
::20
.20
.20
.22
.23
.23
.23
ii

List of IIlustrations
Section 2 - Operation
Figure 2-l
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5
Figure 2-6
Figure 2-7
Figure 2-8
Figure 2-9
Top panel..................... ..........
Front panel. ..........
Charge filter.. ..........
Charge filter schematic ..........
Current standard connections ..........
Charge standard connections. ..........
Unguarded resistance connections. ..........
Guarded resistance connections. ..........
Digital I/O connections ..........
7
8
9
9
. . . ..I1
. . . ..I3
.I5
.I7
. . . ..I8
111

List of Tables
Section2 - Operation
Table 2-l Recommended voltage calibrators 10
Table 2-2 ‘@pica1calibrator voltages for current standard operation 12
Table 2-3 Typical calibrator voltages for charge standard operation. 14
Section 3 -Maintenance
Table 3-l Calibration commands. .2 I

General Information
Introduction
This section contains general information about the Model 5156 Electrometer
Calibration Standard. The Model 5156 contains precision resistance and capaci-
tance standards and is intended for use with voltage calibrators to calibrate or
verify the current and charge measurement accuracy of sensitive instruments
such asthe Model 6517 Electrometer. The unit may also be used in applications
requiring accurate resistance standards.
Features
Model 5156features include:
* Highly stable, characterized standard resistors and capacitors ensure witi-
cation and calibration integrity. Characterization data is supplied with the
unit.
- Internal memory stores standards values to simplify calibrating the Model
6517 Electromctcr.
- Triax and BNC connectors simplify connections to the desired standard.
l Supplied charge filter minimizes the effects of rapid voltage calibrator signal
rise times.
Manual addenda
Any improvements or changes concerning the calibration standard or manual will
be explained in an addendum. Be sure to note these changes and update this doc-
ument accordingly before using the unit.

Safety symbols and terms
The following symbols and tarns may bc found on an instrument or used in this
manual.
The f$~ symbol on an instrument indicates that the user should refer to the
operating instructions located in the instruction manual.
The WARNING heading used in this manual explains dangers that might result
in personal injury or death. Always read the associated information very carefully
before performing the indicated procedure.
The CAUTION heading used in this manual explains hazards that could damage
the calibration standard. Such damage may invalidate the warranty.
Specifications
Model 5156 specifications ax located at the front of this document,
Unpacking and inspection
Inspection for damage
Upon receiving the Model 5156, carefully inspect it for any signs of obvious
physical damage.Report any such damage to the shipping agent immediately.
Handling precautions
When handling the calibration standard, take care not to touch the connector
insulators as doing so could degrade performance. Leave the protective caps on
the connectors when the unit is not being used.
Shipment contents
The following items are included with every Model 5156 order:
- Model 5156 Electrometer Calibration Standard
l Charge filter
* Model 7078.TRX-3 triax connecting cable
* Model 8501-l data transfer cable
* Additional accessories asordered
2

Documentation
If an additional copy of this document is required, order the complete package,
Keithley pat number 5156-901-00. The package includes an instruction manual
and any pertinent addenda.
Repacking for shipment
When returning the Model 5156 for calibration or repair, carefully pack the unit
in its original packing cuton or the equivalent, and include the following infor-
mation:
- Call the Repair Department at I-800-552-1 I I5 for a Return Material Autho-
rization (RMA) number.
* Write ATTENTION REPAIR DEPARTMENT and the RMA numhcr on the
shipping label.
* Advise asto the warranty status of the unit.
* Fill out and include the service form located at the back of this manual.
Optional accessories
The following optional accessories are recommended for use with the Model
5156.
Model 4851 BNC Shorting Plug: Shorts HI and LO terminals of Model 5156
BNC jacks when using the unit asa resistance or capacitance standard.
Model 6171 J-Slot Male to Z-Lug Female Triax Adapter: Allows connection
of 2-slot triax cables to the Model 5156triax OUTPUT jack.
Model 7051 BNC Cables: BNC to BNC cables (RG-SC), available in 0.6m (2
ft.), l.5m (5 ft.), and 3.Om (10 ft.) lengths as Models 7051.2, 7051.5, and 7051.
IO respectively. Useful for connecting equipment such as voltage calibrators to
the Model 5156 BNC jacks.
Model 7078 Wax Cables: Low-noise triax cables terminated with male 3.slot
triax connectors, available in 0.9m (3 ft.), 3.Om(IO ft.), and 6.Om(20 ft.) lengths
asModels 7078.3,707s.IO, and 7078.20 respectively. Use to connect equipment
to the Model 5156triax OUTPUT jack.
3

2
Operation
Introduction
This section contains detailed information on Model 5156 operation, including
connections when using the unit as a current, charge, resistance, and capacitance
standard.
WARNING
The procedures in this section are intended only for quali-
fied service personnel. Some of these procedures may
expose you to potentially lethal voltages.
Definition of a standard
A standard is acomponent whose value hasbeen accurately measured and whose
stability (variation in value over time) can be accurately predicted. Generally.
such standards are measured by equipment with uncertainty that is traceable to
NIST (National Institute of Standards and Technology) standard values.
Model 5156 specifications stated at the front of this document take into account
both the measured value and the stability of each component resistor or capacitor.

Panelfamiliarization
lop panel
Figure 2. I shows the top panel of the Model 5156.The various components include:
BNC Standard Jacks: Each of the four standard resistors and two standard
capacitors is connected to its own individual BNC jack. When used as a current
or charge standard, a DC voltage calibrator is connected to the appropriate jack.
When used as a resistance standard, a BNC shorting plug is connected to the
appropriate jack. Note that each standard is connected to the center conductor,
while the shell of eachjack is connected to chassis ground.
OUTPUT Jack: This 3.lug triax jack is normally connected to the input of the
instrument being tested. The center conductor is internally connected to each of
the resistance and capacitance standards, the inner ring is connected to SHIELD,
and the outer ring is at chassis ground.
WARNING
To assure proper safety grounding, always connect the
OUTPUT jack to the electrometer INPUT jack before
applying voltage to the Model 5156.
CAUTION
Do not exceed ZOOVpeak maximum input voltage.
Characterization Value Label: A label that contains the characterized values of
the standard resistors and capacitors is affixed to the top panel.

+
r71
+ +
Figure 2-l
Toppanel

Front panel
Figure 2-2 shows the front panel. Various components include:
SHIELD: This jack is internally connected to the inner conductor of the triax
OUTPUT jack.
CHASSIS: This jack is connected to Model 5156 chassis.
NOTE
For all operating modes except guarded ohms, SHIELD and
CHASSlS must he jumpered together using the supplied short-
ing link. (See Resistance standard operation later in this sec-
tion for details on guarded ohms connections.)
TO 6517 DIGITAL I/O Jack: This DIN jack connects the unit to the Model
6517 Electrometer when cnlihrating that instrument. Use the supplied data trans-
fer cable to make the connection
Figure 2-3 shows the configuration of the supplied charge filter. The purpose of
the filter is to minimize the effects of rapid voltage calibrator rise times that
would otherwise affect charge measurements.
To usethe charge filter, connect the OUTPUT jack to the 1nF or lOOoFBNC jack
of the Model 5156, and connect the INPUT jack to the DC voltage calibrator
using a suitable BNC cable. Note that the charge filter should he used only for
8

TO
5156
BNC
Jack
TO
Calibrator
Figure 2-3
Chargefilter
charge measurements and should not bc connected when the Model 5156 is being
used asa current, rcsistancc, or capacitance standard.
Figure 2-4 shows a schematic of the charge filter, which is a simple RC network
that forms a.single-pole, low-pass filter.
Figure 2-4
Charpjilter .schematic
Testconsiderations
* Use the Model 5I56 at an ambient temperate of 23” +3”C.
- Do not touch triax or BNC jack insulators. If the insulators become contami-
nated, they should he carefully clenncd ascovcrcd in Section 3.
* Keep caps on connecting jacks when not in USC.
* Use only quality connecting cables, and keep cables asshort aspossible.
- Do not flex or vibrate cables while making measurements.
- Perform all tests at a stable ambient temperature and humidity recommended
by equipment manufacturers.
Recommended voltage calibrators
A DC voltage calibrator is required when using the Model 5156 as a current or
charge standard. Table 2-1 summarizes recommended calibrators.

Table 2-1
Recommended voltage calibrators
~~~
Current standard operation
Current connections
Figure 2-5 shows connections for operation asa current standard. When making
connections:
- Connect the Model 5156 OUTPUT jack to the INPUT jack of the instru-
ment being tested using a suitable triax cahlc.
WARNING
To assure proper grounding, connect the Model 5156 OUT-
PUT jack to the instrument INPUT jack before applying
voltages to the standard.
- Connect the appropriate resistance standard jack to the DC voltage calihra-
tar using a BNC cable and adapter.
- Be sure that the Model 5156 SHIELD and CHASSIS jacks on the front
panel are connected together.
CAUTION
Do not apply more than 200V peak to the Model 5156.
Current calculations
The generated current value may he calculated from the standard resistance and
calibrator voltage asfollows: I=V/R
Where: I = generated current.
V = calibrator voltage.
R = resistance standard value.