IET Labs HPRS Series Troubleshooting guide

PRECISION INSTRUMENTS FOR TEST AND MEASUREMENT 
Email: inf[email protected]
TEL: [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.
Copyright © 2018 IET Labs, Inc.
Visit www.ietlabs.com for manual revision updates
HPRS im/Sept. 2018
HPRS SERIES
High-Power Decade
Resistance Substituter
User and Service Manual

Email: inf[email protected]
TEL: [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.

3
HPRS Series
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.

4
HRRS Series
Revision History:
Date Description By
March 2013 Initial release LB
Sept 2018 Major update for standardization of marking
and required information in the manual
BB

5
HRRS Series
SAFETY SUMMARY
The following general safety precautions must be observed during all phases of operation,
service, and repair of this instrument. Failure to comply with these precautions or with
specifi c WARNINGS elsewhere in this manual may impair the protection provided by the
equipment. Such noncompliance would also violate safety standards of design, manufacture,
and intended use of the instrument.
IET Labs assumes no liability for the customer’s failure to comply with these precautions.
The HPRS Series comply with INSTALLATION CATEGORY I as well as POLLUTION
DEGREE 2 as defi ned in IEC61010-1.
Voltages of up to 1000 Vdc maybe present at measurement terminals.
If an instrument is marked CAT I (IEC Measurement Category I), or it is not marked with a
measurement category, its measurement terminals must not be connected to line-voltage
mains and it is not designed for use as for measurements within measurement categories
II, III and IV,
The HPRS Series are an indoor use product.
DANGEROUS PROCEDURE WARNINGS
Comply with all WARNINGS - Procedures throughout in this manual prevent you from
potential hazard. These instructions contained in the warnings must be followed.
BEFORE APPLYING POWER
Verify that all safety precautions are taken. Make all connections to the instrument
before applying power. Note the instrument’s external markings described under “Safety
Symbols”.
GROUND THE INSTRUMENT
This is a Safety Class I instrument. To minimize shock hazard, the instrument chassis and
cabinet must be connected to an electrical ground. The power terminal and the power
cable must meet International Electrotechnical Commission (IEC) safety standards.

6
HRRS Series
SAFETY SUMMARY CONTINUED
CAUTION
• DO NOT Operate in an Explosive Atmosphere
• DO NOT operate the instrument in the presence of infl ammable gasses or fumes
• Operation of any electrical instrument in such an environment clearly constitutes a
safety hazard
• Use Caution around live circuits
• To prevent electrical shock operators must not remove instrument covers
• Component replacement and internal adjustments must be made by qualifi ed
maintenance personnel only
• DO NOT substitute parts or modify the instrument
• There are no user serviceable parts inside.
• Refer servicing to qualifi ed personnel.
• Only replaced fuses with correct size and rating to prevent electrical shock
To avoid the danger of introducing additional hazards, do not install substitute parts or perform
unauthorized modifi cations to the instrument.
Return the instrument to an IET Labs for service and repair to ensure that safety features are
maintained in operational condition.

7
HRRS 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.

Contents
WARRANTY ............................................................................................ 3
Revision History ....................................................................................... 4
Safety Summary ........................................................................................ 5
WARNING ................................................................................................ 7
Chapter 1
INTRODUCTION ............................................................................ 9
Chapter 2
SPECIFICATIONS ........................................................................ 10
Chapter 3
INSTALLATION .......................................................................... 12
3.1 Initial Inspection ................................................................. 12
3.2 Installation .......................................................................... 12
3.3 Storage ................................................................................ 12
Chapter 4
OPERATION .................................................................................. 13
4.1. General Considerations ....................................................... 13
4.2 Duty Cycle ........................................................................... 13
4.3 Electrical Considerations ..................................................... 13
4.4 Dial Setting .......................................................................... 13
4.5 Environmental Conditions ................................................... 13
Chapter 5
MAINTENANCE ........................................................................... 14
5.1 Preventive Maintenance ....................................................... 14
5.2 Verifi cation of Performance ................................................. 14
5.2.1 Calibration Interval ..................................................... 14
5.2.2 General Considerations ............................................... 14
5.2.3 Procedure ..................................................................... 14
5.3 Schematic and Replacement Parts ....................................... 15
5.4 Troubleshooting .................................................................. 15
5.5 Disassembly, Component Replacement, and Reassembly ... 15
5.5.1 Disassembly ................................................................ 15
5.5.2 Component Replacement ............................................ 15
5.5.3 Reassembly .................................................................. 15
5.6 Customer Service ................................................................ 15
5.7 Instrument Return ............................................................... 16

9
INTRODUCTION
HPRS Series
Chapter 1
INTRODUCTION
The High-Power Decade Resistance Substituter
(HPRS) Series is a family of instruments off ering a
broad choice of high-power, excellent-performance
resistance sources (Figure 1.1). High-power resistors
are made available without sacrifi cing other electrical
properties. Any number of decades is available in a
choice of two accuracies.
The HPRS Series employs state-of-the-art precision
resistors of various types for high accuracy, high
stability, and low temperature and power coeffi cients-
of-resistance.
The standard models off er a choice of three to nine
decades. The panels are clearly labeled showing the
step size and maximum voltage and current limita-
tions for each decade.
With a resolution as low as 1 m and a maximum
resistance of 10 M , the HPRS Series may be used
as a general purpose substituter as well as a high-
power load for testing power supplies and for other
high-power applications.
Applications include calibration of meters and instru-
ments. HPRS instruments are useful development
tools wherever precise resistances with high-power
handling capacity are required.
It is important to keep the amount of time power is
applied the the HPRS within the duty cycles below.
The duty cycles assume an ambient temperature of
around 230C.
Power Time on Time off
<101 W continuous none
>101 W 5 minutes 10 minutes
Exceeding the time on can cause damage to the
resistors.
If continuous use is required to full rated power see
DRS-900 High Power Resistance Substituter.
Figure 1.1 DRS-900 High-Power Decade
Resistance Substituter
The HPRS series complements the HRRS and HARS
series, providing resistance steps as low as 1 m The
units may be rack-mounted to serve as components
in measurement and control systems.
This series is part of a family of resistance substitut-
ers suited to fi ll many engineering and testing needs.
Consult IET for:
High power substituters - up to 400 W
High resistance substituters - to 1 T
RTD simulators
Laboratory-standard-gradesubstituters- to 20 ppm
accuracy
Programmable substituters - IEEE-488, USB or
Ethernet.
Figure 1.2 HPRS Series High-Power Decade
Resistance Substituter

10 SPECIFICATIONS
HPRS Series
Chapter 2
SPECIFICATIONS
ORDERING INFORMATION
Model*
(1.0% accuracy shown)
Total
resistance
()
No of
Dials
Resolution
()
HPRS-F-3-0.001 0.999 3 0.001
HPRS-F-3-0.01 9.99 3 0.01
HPRS-F-3-0.1 99.9 3 0.1
HPRS-F-3-1 999 3 1
HPRS-F-3-10 9.99 k 310
HPRS-F-3-100 99.9 k 3 100
HPRS-F-3-1K 999 k 31k
HPRS-F-3-10K 9.99 M 3 10 k
HPRS-F-4-0.001 9.999 4 0.001
HPRS-F-4-0.01 99.99 4 0.01
HPRS-F-4-0.1 999.9 4 0.1
HPRS-F-4-1 9.999 k 4 1
HPRS-F-4-10 99.99 k 4 10
HPRS-F-4-100 999.9 k 4 100
HPRS-F-4-1K 9.999 M 4 1 k
HPRS-F-5-0.001 99.999 5 0.001
HPRS-F-5-0.01 999.99 5 0.01
HPRS-F-5-0.1 9.999 9 k 5 0.1
HPRS-F-5-1 99.999 k 5 1
HPRS-F-5-10 999.99 k 5 10
HPRS-F-5-100 9.999 9 M 5 100
Model*
(1.0% accuracy shown)
Total
resistance
()
No of
Dials
Resolution
()
HPRS-F-6-0.001 999.999 6 0.001
HPRS-F-6-0.01 9.999 99 k 6 0.01
HPRS-F-6-0.1 99.999 9 k 6 0.1
HPRS-F-6-1 (HPRS-150) 999.999 k 6 1
HPRS-F-6-10 9.999 99 M 6 10
HPRS-F-7-0.001 9.999 999 k 7 0.001
HPRS-F-7-0.01 (HPRS-200) 99.999 99 k 7 0.01
HPRS-F-7-0.1 999.999 9 k 7 0.1
HPRS-F-7-1 9.999 999 M 7 1
HPRS-F-0.001 99.999 999 k 8 0.001
HPRS-F-8-0.01 999.999 99 k 8 0.01
HPRS-F-8-0.1 (HPRS-200W) 9.999 999 9 M 8 0.1
* For 0.5% accuracy, substitute "C" for "F" in part number
Options:
-RM for rack mountable version
For programmable versions see PRS-300 and PRS-200/202
Accuracy:
after subtraction of zero resistance, at 23°C; traceable to SI
Option F: ±(1% + 20 mΩ)
Option C: ±(0.5% + 20 mΩ)
Zero Resistance:
<5 mΩ per decade
Terminals:
Two fi ve-way binding posts and one ground post electrically
connected to case.
Dimensions:
43.9 cm W x 8.9 cm H x 10.2 cm D (17.3" W x 3.5" H x 4" D)
Weight:
2.4 kg (5.3 lbs), nominal
SPECIFICATIONS
Resistance
per step
Total
decade
resistance
Max
current*
Max power
per step*
(W)
Temperature
coefficient
(ppm/°C)
Resistor
Type
1 m0.009 8 A 0.036 ±50
Resistance
Wire
10 m0.09 6 A 0.36 ±50
100 m0.9 6 A 3.6 ±20
1 9 5 A 25 -20 to +80
Power
Film
10 90 1.5 A 25 -20 to +80
100 900 0.5 A 25 -20 to +80
1 k9 k150 mA† 25† -20 to +80
10 k90 k50 mA† 25† -20 to +80
100 k900 kV limit† V limit† -20 to +80 Wirewound/
metal film
1 M9 MV limit† V limit† ±50 Wirewound/film
*Subject to maximum of 250 W max. per unit
†Subject to 1000 V (dc+ac) peak max