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Model 262 Low Thermal Voltage Divider
Instruction Manual
WARRANTY
Keithley Inslrumenls. Inc. warrants this producl to be free from defects in material
and workmanship for a period of I year from date of shipmem.
Keithley Inslrumen&. Inc. warranls 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 Ihal proves to be defecrive.
To exercise [his warranty, write or call your local Keithley representative. or con-
lacr Keithley headquarrers in Cleveland, Ohio. You will be given prompt assistance
and return inslructions. Send lhe product, lransportation prepaid, to rhe indicated
service facilily. Repairs will be made and the product returned, transportation pre-
paid. Repaired or replaced producls are warranted for the balance of the original
warranty period, or al leas1 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modilication withoul
Keithley's express wrilten consem, or misuse of any producl or pan. This warranty
also does not apply to fuses. sofware. non-rechargeable batteries, damage from bal-
tery leakage. or problems arising from normal wear or failure 10follow instructions.
THIS WARRANTY IS IN LIEU OFALL 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.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOY-
EES SHALL BE L1ABI.E FOR ANY DIRECT, INDIRECT, SPECIAL, INCI-
DENTAL OR CONSEQIJENTIAL DAMAGES ARISING OUT OF THE USE OF
ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRU-
MENTS, INC.. HAS BEEN ADVISED IN ADVANCE OF THE POSSlBlLITY
OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE,
BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION,
LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR
DAMAGETO PROPERTY.
Model 262 Low Thermal Voltage Divider
Instruction Manual
@1982, Keithley Instruments, Inc.
All rights rcservcd.
Cleveland, Ohio, U.S.A.
Fourth Printing, May 2000
Document Number: 262-901-01 Rev. D
Safety Precautions
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 arc situations where hazardous conditions may bc 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 the upcrating in-
formation carefully before using the product.
The types of product users are:
Responsible body is the individual or group responsible for the use and maintenance of
equipment, for cnsuring 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 vained in electrical safety
procedures and proper use of the inatmment. They must be protected from elec(nc shock and
contact with hazardous live circuits.
Maintenance personnel perform routine procedures on the product to keep it operating, for
example, setting the line voltage or replacing consumable materials. Maintenance procedures
arc 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 rc-
pairs of products. Only properly trained service personnel may perform installation and ser-
vice procedures.
Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on
cable connector jacks or test lixtures. The American National Standards Institute (ANSI)
sratcs 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 befure measuring.
Users of this pmduct must be protected from elecaic shock at all times. The responsible body
mustenwe tidt usersare prevented accessand/or insulated fromevery connection point. In some
cases,connections must be exlxxd to potential human confacf. Product users in these circun-
stancesmust be trained to pro&t themselves from the risk of electric shock. If the circuit is ca-
pable of operating at or above loo0 volts, no conductive part of the circuit may be exposed.
As described in the International Electrotechnical Commission (IEC) Standard IEC 664, dig-
ital multimeter measuring circuits (e.g.. Keitbley Models l75A, 199,2OOO,2001, 2002, and
2010) are Installation Category II. All other instruments' signal terminals are installation Cat-
egory I and must not be connected to mains.
Do not connect switching cards directly to unlimited power circuits. They arc 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 currcnt
and voltage to the card.
Before operating an insuument, make sure the line cord is connected to a properly grounded
power receptacle. Inspect the connecdng cables, test leads, and jumpers for possible wear,
cracks. or breaks before each use.
For maximum safety, do not touch the product, test cables. or any other instmments while pow-
er is applied to the circuit under test. ALWAYS remove power from the entire test system and
discharge any capacitors beforo: 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 he used in accordance with its specifications and op-
erating instructions or the safety of the equipment may he impaired.
Do not excwd the maximum signal levels of the instruments and accessories, as de6ned 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 he used ns shield connections for measuring circuits, NGT as
safety earth ground connections.
If you are using a test lixture. keep the lid closed while power is applied to the device under
test. Safe operation requires the use of a lid interlock.
Ifa @ screw is present, connect it to safety earth ground using the wire recommended in
the user documentation.
The A symbol on 8.n instrument indicates that the user should refer to the operating in-
structions located in the manual.
Then. symbol on an insbument shows that it can source or measure 10X volts or more, in-
cluding the combined effect of normal and common mode voltages. Use standard safety precnu-
tions 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 indicated
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 pnwer transformer, test leads, and input jacks, must be purchased from
I-&id&y Insh'uments. Standard fuses, with applicable national safety approvals, may be used
if the rnting and type are the same. Other components that are not safety related may he pur-
chased from other suppliers as long as they nre equivalent to the original component. (Note
that selected parts should he purchased only through Keitbley Instruments to maintain nccu-
racy and functionnlity 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, writer based cleaner. Clean the exterior
of the instrument only. Do not apply cleaner directly to the instruiuent or allow liquids to
enter or spill on the instrument. Products that consist of a circuit board with no case or chas-
sis (e.g., data acquisition board for installation into a computer) should never require clean-
ing if handled according to instructions. If the board becomes contaminated and operation
is affected, the board should be returned to the factory for proper cleaning/servicing.
Rc".10199
SPECIFICATIONS
ACCURACY TEMI'ARATURE OUTPUT
DIVIDER (1 Year)* COEFFICIENT NOISE THERMAL
RATIO 220-24'C W280C (O.lHz Bw) DRIFT**
101 : 1 * 35ppm 2ppmPC 1onv p-p 1onv
103 : 1 * 35ppm 2ppmPC 1onv p-p 1onv
10' : 1 *lOOppm 10ppmPC 1nv p-p 3nV
105 : 1 *lOOppm lOppm/Yz 1nv p-p 3nv
*Referenced to output terminals.
**br ambient temperature changes ~1"Clhour. Includes effects of sup-
plied cable.
INPUT RESISTANCE: 20khl for divider ratios of lo?1 and 1O':l; 200kn
for divider ratios of lo':1 and 105:1.
OUTPUT RESISTANCE: 261 divider ratios of lo':1 and 10s:l; 2000
for
for divider ratios of lo':1 and lO?l.
OVERLOAD PROTECHON: Maximum operating input voltage is 20V.
Input is protected against 1OOOV overloads from calibrators with cur-
rent limits up to 150mA.
CONTROLS: Polarity and divider ratio.
CONNECTORS: Input: 5.~3~ binding posts for input, sense, and case
ground. Output: Special low thermal female connector; mates with
Models 1506, 1507, 1481, and 1482.
ENVIRONMENTAL LIMITS: Operating: 18%28'C, 0 to 60% relative
humidity. Storage: -25" to 65