IET Labs 1433-33 User And Service Manual

♦

PRECISION INSTRUMENTS FOR TEST AND MEASUREMENT

♦

1433 SERIES

High-Accuracy

Decade Resistor

User and Service Manual

Copyright © 2013 IET Labs, Inc.

Visit www.ietlabs.com for manual revision updates

1433 im/November 2014

Effective for serial numbers beginning with “E”

IET LABS, INC.

www.ietlabs.com

Email: [email protected]

TEL: (516) 334-5959 • FAX: (516) 334-5988

IET LABS, INC.

www.ietlabs.com

Email: [email protected]

TEL: (516) 334-5959 • FAX: (516) 334-5988

WARRANTY

We warrant that this product is free from defects in material and workmanship and, when properly used, will perform in accordance with applicable IET specifi cations. If within one year after original shipment, it is found not to meet this standard, it will be repaired or, at the option of IET, replaced at no charge when returned to IET. Changes in this product not approved by IET or application of voltages or currents greater than those allowed by the specifi cations shall void this warranty. IET shall not be liable for any indirect, special, or consequential damages, even if notice has been given to the possibility of such damages.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED,

INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR

FITNESS FOR ANY PARTICULAR PURPOSE.

1433 Series

Table of Contents i

ii

1433 Series

WARNING

OBSERVE ALL SAFETY RULES

WHEN WORKING WITH HIGH VOLTAGES OR LINE VOLTAGES.

Dangerous voltages may be present inside this instrument. Do not open the case

Refer servicing to qualifi ed personnel

HIGH VOLTAGES MAY BE PRESENT AT THE TERMINALS OF THIS INSTRUMENT

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 WHEN USING THIS INSTRUMENT.

Use extreme caution when working with bare conductors or bus bars.

WHEN WORKING WITH HIGH VOLTAGES, POST WARNING SIGNS AND

KEEP UNREQUIRED 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.

Table of Contents

Contents

Chapter 1 Introduction ..............................................................................1

Chapter 2 Specifi cations ...........................................................................2

Decade Specifi cations .................................................................................................... 2

Chapter 3 Operation ..................................................................................5

3.1 Initial Inspection and Setup .................................................................................. 5

3.2.3 Four-Wire Kelvin-Lead Connections ......................................................... 6

3.2.4 Thermal emf Considerations ....................................................................... 6

Chapter 4 Maintanence ..............................................................................7

1433 Series

4.6 Replaceable Parts List ........................................................................................... 9

Table of Contents iii

1433 Series

Tables and Figures

Figure 1-1: 1433 Series High Accuracy Decade Resistor ....................................... 1

Figure 2-1: Sample operating guide affi xed to unit ................................................. 4

Figure 3-1: Optimal 4-Wire Kelvin Lead Connection ............................................... 6

Figure 4-1: 1433 Series Schematic Diagram .......................................................... 8

Table 4-1: Replacement List .................................................................................... 9

Figure 4-2: 1433 Replaceable Parts ....................................................................... 9

iv Table of Contents

1433 Series

Chapter 1

INTRODUCTION

The 1433 Decade Resistors are a family of instruments providing a very broad choice of high-performance resistance sources. Any number of decades from one to eleven is available.

The 1433 is a precision resistance source with excellent characteristics of stability, temperature coeffi cient, power coeffi cient, and frequency response.

There are over 30 models available covering a wide resistance range from 1 m

Ω to over 111 MΩ. The

1433 Series employs stable, very-low-resistance switches with silver-alloy contacts. A special design keeps zero-resistance to less than 1 m

Ω 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.

The dials, marked “0” to “10”, offer smooth rotation from position to position with no stops. Each dial has an overlap “10” position for maximum convenience and fl exibility in setting and adjusting resistance values. The resistance per step and maximum current of each dial are clearly shown on the front panel.

Electrical shielding is provided by an attractive aluminum cabinet and front panel. The resistance elements have no electrical connection to the cabinet and panel; a separate shield terminal is provided.

High-quality gold-plated, tellurium-copper binding posts serve to minimize the thermal emf effects which can introduce errors into dc resistance measurements.

All other conductors within the instrument, as well as the solder employed, contain no metals or junctions that contribute to thermal emf problems.

With a minimum resistance as low as 1 m

Ω and a maximum available resistance of over 111 M

Ω, the

1433 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 1433 Series may be rack-mounted to serve as components in measurement and control systems.

This series is part of a family of resistance substituters suitable for fi lling many engineering and testing needs. Consult IET for:

HPRS High-power substituters - up to >400 W

HRRS High-resistance substituters - to 1 T

Ω

RTD simulators

HARS-LX Laboratory-standard-grade substituters - to 1 ppm accuracy

PRS Programmable substituters - IEEE-488 or

BCD; SCPI protocol.

Figure 1-1: 1433 Series High Accuracy

Decade Resistor

Introduction 1

1433 Series

2

Chapter 2

SPECIFICATIONS

For the convenience of the user, the pertinent specifi cations are given in an OPERATING GUIDE affi xed to the case of the instrument.

Decade Specifi cations

Resistance per step

1 mΩ

Total decade resistance

10 mΩ

10 mΩ

100 mΩ

Max current

Max voltage

(per step)

8.0 A

4.0 A

5 mV

40 mV

1 Ω 1.6 A 0.16 V

Max power

(per step)

Stability

(±ppm/yr)

0.04 W

0.16 W

0.25 W

Long-term stability

(±ppm/3 yrs)

50

100 mΩ

1 Ω

10 Ω

100 Ω

1 kΩ

10 kΩ

10 Ω

100 Ω

1 kΩ

10 kΩ

100 kΩ

0.8 A

0.25 A

80 mA

23 mA

7 mA

0.8 V

2.5 V

8 V

23 V

70 V

0.6 W

0.6 W

0.6 W

0.5 W

0.5 W

Temperature coeffi cient

(±ppm/°C)

20

100 kΩ

1 MΩ

10 MΩ

1 MΩ

10 MΩ

100 MΩ

2.3 mA*

0.7 mA*

0.1 mA*

230 V*

700 V*

1000 V*

0.5 W*

0.5 W*

0.1 W*

*Subject to maximum of 2000 V to case

Resistor type

inductive

Accuracy:

≤1 MΩ decades: ±(0.01% + 2 mΩ)

10 MΩ decades: ±0.03%

after subtraction of zero resistance, at 23°C; traceable to SI

Zero resistance:

≤1 MΩ decades: <1 mΩ per decade at dc

10 MΩ decade: ≈3 mΩ at dc

Max voltage to case:

2000 V peak

Terminals:

3 Gold-plated, 5-way, tellurium-copper binding posts with low thermal emf and low resistance. Rear outputs are available as an option.

-K Option: Kelvin connection to is available as an option with 5 binding posts

Typical Value of Zero Impedance:

Zero Resistance (Ro):

<0.001 Ω/decade at dc

0.04 Ω/decade at 1 MHz

Proportional to square root of frequency above 100 kHz

Switch capacitance:

< 1 pF between contacts

Zero Inductance (Lo):

0. 1 μH/decade + 0.2 μH.

Switches:

Continuous rotation

11 positions marked “0”-”10”

Multiple solid silver-alloy contacts

Environmental conditions:

Operating: 10°C to 40°C

Storage: -40°C to 70°C

Humidity: <80% RH

Supplied with unit:

Instruction manual

Calibration Certifi cate

Specifi cations

1433 Series

Mechanical:

3 decade

4-5 decade

6-7 decades

8-9 decades

10-11 decades

31 cm W x 8.9 cm H x 10.2 cm D

(12.2" x 3.5" x 4")

37.6 cm W x 8.9 cm H x 10.2 cm D

(14.8" x 3.5" x 4")

43.9 cm W x 8.9 cm H x 10.2 cm D

(17.3" x 3.5" x 4")

48.3 cm W x 17.8 cm H x 17.8 cm D

(19" x 7" x 7")

1.7 kg 3.8 lb

2.0 kg 4.3 lb

2.4 kg 5.3 lb

3.5 kg 7.7 lb

3.7 kg 8.1 lb

Ordering Information:

1433-01

1433-00

1.11

Ω

111.1

Ω

1433-02

1.111 k

Ω

1433-04

1433-06

1433-08

1433-10

1.111 M

Ω

1433-09

11.11 M

Ω

1433-09A

111.1 M

Ω

1.1111 k

Ω

1433-12

1433-14

11.11 k

Ω

111.1 k

Ω

11.111 k

Ω

111.11 k

Ω

1433-16

1433-18

1433-22

1.1111 M

Ω

11.111 M

Ω

1433-18A

111.11 M

Ω

1433-19

1.111 11 k

Ω

1433-20

11.1111 k

Ω

111.111 k

Ω

1433-24

1433-26

1.111 11 M

Ω

11.1111 M

Ω

1433-27

1433-28

111.111 M

Ω

11.111 11 k

Ω

1433-29

111.1111 k

Ω

1433-31

1433-33

1.111 111 M

Ω

11.111 11 M

Ω

Number of decades

Resolution

Historic

GR model numbers

1433-U

1433-K

1433-J

1433-L

1433-Q

1433-T

1433-N

1433-M

1433-P

1433-Y

1433-W

1433-X

1433-B

1433-Z

1433-F

1433-G

1433-H

1433-34

1433-35

111.1111 M

Ω

111.111 11 k

Ω

1433-36

1.111 111 1 M

Ω

1433-37

1433-38

11.111 111 M

Ω

111.111 11 M

Ω

1433-39

1.111 111 11 M

Ω

1433-39A

11.111 111 1 M

Ω

1433-39B

111.111 111 M

Ω

1433-40A

11.111 111 11 M

Ω

1433-40

111.111 111 1 M

Ω

1433-41

111.111 111 11 M

Ω

Number of decades

Resolution

Historic

GR model numbers

OPTIONS:

1433-50: Rack Mount Kit (4-dial)

1433-51: Rack Mount Kit (5-dial)

1433-52: Rack Mount Kit (6 and 7-dial)

1433-XX-RO: Rear output binding posts

1433-XX-K: Kelvin-type 4-terminal posts

Specifi cations 3

1433 Series

4 Specifi cations

1433 Series

Chapter 3

OPERATION

3.1 Initial Inspection and Setup

This instrument was carefully inspected before shipment. It should be in proper electrical and mechanical order upon receipt.

An OPERATING GUIDE is attached to the case of the instrument to provide ready reference to specifi cations.

3.2 Connection

The 1433 Series Decade unit provides three terminals labeled H (high), L (low), and G (ground). The H and

L terminals are connected to the set resistance; the G terminal is connected to the case. The G terminal may be used as a guard or shield terminal. It may also be connected (using a shorting link) to the L terminal to allow two-terminal as opposed to three-terminal measurements.

In order to make the most stable measurements, determine which is the more sensitive of the two user leads, i.e. the one going into a higher impedance. This lead should be connected to the more protected of the two terminals: H (high) or L (low). That would either be the terminal that is shorted to the case, or the L terminal if neither is connected to the G (case).

If switches have not been operated for an extended period, they should be rotated a few times to assure that contact resistance is within specifi cations.

In order to make proper use of the full performance capabilities of the 1433 unit, especially if low resistance or low-resistance increments are important, take care when connecting to the terminals. In particular, in order to keep contact resistance to a minimum, make the most substantial and secure connection to the binding posts. They accept banana plugs, telephone tips, spade lugs, alligator clips, and bare wire.

The largest or heaviest mating connection should be made, and, where applicable, the binding posts should be securely tightened.

These considerations may be relaxed whenever single milliohms are considered insignifi cant for the task being performed.

Operation 5

1433 Series

Connections

Whenever possible, 4-wire Kelvin leads (the best connection) should be employed. Such a connection minimizes the effects of contact resistance and approaches ideal performance.

If the four terminals are available as clamps similar to alligator clips, they may be connected to the necks of the binding posts on a 3-terminal unit. If the fourwire connections are available separately, the optimal connections are shown in Figure 3-1 and Figure3-2.

I+ IGround

V+

HIGH

SENSE

I+

V-

LOW

SENSE

IGround

V+ V-

HIGH LOW GND

Figure 3-1: 4-Wire connection to a 3-terminal unit

HIGH

CURRENT

LOW

CURRENT

GND

Figure 3-2: 4-Wire connection to a 5-terminal unit

6 Operation

1433 Series

3.2.4 Thermal emf Considerations

The highest-quality low-emf components are used in the 1433 Series. There nevertheless may be some minute thermal emf generated at the test leads where they contact the gold-plated binding posts.

This emf will not manifest itself if an ac measurement instrument is employed. It will also be eliminated if a meter with a “True Ohm” capability is used.

Otherwise it may appear as a false component of the dc resistance measurement. It is possible to eliminate this component of the reading error by taking a second measurement with the leads reversed and averaging the readings.

Whenever the dials are used in positions 0-9, the resulting resistance is read directly. The decimal point and the steps are clearly marked on the panel.

For additional fl exibility and range, each decade provides a “10” position setting. This “10” position on any one decade equals the “1” position on the next higher decade. It adds about 11% to the nominal total decade resistance.

To determine the resistance obtained when one or more “10” settings are used, simply add “1” to the next higher decade. For example, a setting of 3-6-

10-0-10 Ω becomes:

3

6

1 0

0

10

3 0 0 0 0

6 0 0 0

1 0 0 0

0 0

1 0

____________________________

TOT 3 7 0 1 0

and a setting of 10-10-10-l0-10.10

Ω becomes:

10

10

10

10

1 0 0 0 0 0.0

1 0 0 0 0.0

1 0 0 0.0

10

.10 1.0

____________________________

TOT 1 1 1 1 1 1.0

Operation 7

1433 Series

Chapter 4

MAINTANENCE

8

Keep the unit in a clean environment. This will help prevent possible contamination.

The 1433 is packaged in a closed case, which limits the entry of contaminants and dust to the inside of the instrument. If it is maintained in a clean or airconditioned environment, cleaning will seldom be required. In a contaminated atmosphere, cleaning may be required.

Should cleaning be needed, do the following:

1. Remove the 4 screws from the sides of the housing, and remove the housing.

2. Remove any dust or debris using optical grade dry compressed air or a clean brush.

3. Should switch contact cleaning or lubrication be required, as may be indicated by an increase in the zero resistance, this may be done be spraying the switch contacts with a conditioning compound such as WD-40 or Deoxit from Caig Laboratories, or Super

Lube with PTFE from Synco Chemical Corp.

4. Replace the housing and reinstall the 4 housing screws.

The front panel should be periodically cleaned to eliminate any leakage paths around the binding posts.

To do this wipe the front panel clean using alcohol and a lint-free cloth.

The recommended calibration interval for 1433

Series decade substituters is twelve (12) months. The calibration procedure may be carried out by the user if a calibration capability is available, by IET Labs, or by a certifi ed calibration laboratory.

If the user should choose to perform this procedure, then the considerations below should be observed.

It is important, whenever testing the 1433 Series

Decade Units, to be very aware of the capabilities and limitations of the test instruments used. A resistance bridge may be employed, and there are direct-reading resistance meters or digital multimeters available that can verify the accuracy of these units, especially when used in conjunction with standards that can serve to confi rm or improve the accuracy of the testing instrument

Such test instruments must be signifi cantly more accurate than ±(l00 ppm+2 m

Ω) for all applicable ranges, allowing for a band of uncertainty of the instrument itself. A number of commercial bridges and meters exist that can perform this task; consult IET Labs.

It is important to allow both the testing instrument and the 1433 to stabilize for a number of hours at the nominal operating temperature of 23

°

C, and at nominal laboratory conditions of humidity <80% RH.

There should be no temperature gradients across the unit under test.

Maintanence

1433 Series

Substantial Kelvin-type 4-wire test terminals should be used to obtain accurate low-resistance readings.

It is convenient, once the zero resistance has been determined, to subtract it from the remaining measurements. This can be automatically done in many instruments which have an offset subtraction capability.

4.5 Schematic

Figure 4-1 gives the schematic of the 1433 decade unit.

1. Employ proper metrological practices.

Allow a confi dence band for the uncertainty of the measuring instrument and setup.

2. Confi rm the zero resistance of the unit.

3. Determine the allowable upper and lower limits for each resistance setting of each decade based on the specifi ed accuracy.

For the 1433 series, these limits for any resistance “R” are [R±(0.0001 R + 2 mΩ)].

4. Confi rm that the resistances fall within these limits after subtraction of the zero resistance.

5. If any resistances fall outside these limits, the associated switch assembly may require trimming or replacement.

Maintanence

Figure 4-1: 1433 Series Schematic Diagram

9

1433 Series

4.6 Replaceable Parts List

Model Ref

1

2

3

4

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

Not Shown

IET Pt No

BP-1000-RD

BP-1000-BK

BP-1000-GN

1433-4300-KNB

1433-3100

1433-4000-X-.001

1433-4000-X-0.01

1433-4000-X-0.1

1433-4000-X-1

1433-4000-X-10

1433-4000-X-100

1433-4000-X-1k

1433-4000-X-10k

1433-4000-X-100k

1433-4000-X-1M

1433-4000-X-10M

Table 4-1: Replacement List

Description

Binding Post, Red

Binding Post, Black

Binding Post, Green

Knob Assembly

Foot

1 mΩ/step Decade Switch Assembly

10 mΩ/step Decade Switch Assembly

100 mΩ/step Decade Switch Assembly

1 Ω/step Decade Switch Assembly

10 Ω/step Decade Switch Assembly

100 Ω/step Decade Switch Assembly

1 kΩ/step Decade Switch Assembly

10 kΩ/step Decade Switch Assembly

100 kΩ/step Decade Switch Assembly

1 MΩ/step Decade Switch Assembly

10 MΩ/step Decade Switch Assembly

4

1

2

3

Figure 4-2: 1433 Replaceable Parts

10 Maintanence