Tegam R1L-D1 Operation And Maintenance Manual

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R1L-D1

HIGH ACCURACY MICROOHMMETER

AND RTD MONITOR

MODEL R1L-D1

Operation and Maintenance Manual

PN# R1L-D1-900-01

Publication Date: March 2017

REV. H

Applies to s e rial number s 10100 and above for units purchased under U.S. Government contract, and serial numbers
2010114R1L-D1 and above for all other units. This manual supersedes all revisions of Operation and Maintenance Manual
(Commercial Version), PN R1L-D1-900-02.

REPRODUCTION AND DISTRIBUTION OF THIS TECHNICAL MANUAL IS AUTHORIZED FOR US GOVERNMENT PURPOSES ONLY.

NOTE: This User’s Manual was as current as possible when this product was manufactured. However,
products are constantly being updated and improved. To ensure you have the latest documentation,
please refer to www.tegam.com.

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R1L-D1

(Inside of Cover, intentionally blank)

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TABLE OF CONTENTS

TABLE OF CONTENTS

1. INSTRUMENT DESCRIPTION

Purpose ............................................................... 1-1

Performance Characteristics ................................... 1-1

Table 1: Ranges ...............................................1-1

Table 2: Specifications ......................................1-1

Description of Equipment ....................................... 1-3

Figure 1: Front Panel Layout ............................... 1-6

List of Items Furnished .......................................... 1-7

Tools & Test Equipment Required for Maintenance ..... 1-7

Storage and Shipping Requirements ........................ 1-7

2. PREPARATION FOR USE AND INSTALLATION

Unpacking and Inspection ...................................... 2-1

Preparation for Use................................................ 2-1

3. OPERATI NG INSTRUCTIONS

Pushbutton Functions ............................................ 3-1

2, 3, and 4-Wire Operation ..................................... 3-3

4. MAINTENANCE

Inspection ............................................................ 4-1

Cleaning .............................................................. 4-1

Test Equipment required for Calibration and Repair ... 4-1

Performance Verification ........................................ 4-2

Calibration ........................................................... 4-4

Troubleshooting .................................................... 4-8

Table 3: Fault Symptoms and Repair Actions ........ 4-9

Preparation for Shipment ..................................... 4-11

Overhaul Inst ructions .......................................... 4-11

Figure 2: Assembly Drawing ............................. 4-13

Figure 3: Battery Assembly Drawing .................. 4-14

Figure 4: Main Board Parts Layout ..................... 4-15

5. SERVICE INFORMATION

Preparation for Repair or Calibration Service ............. 5-1

Expedite Repair and Calibration Form ...................... 5-2

Warranty .............................................................. 5-3

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1-1

INSTRUMENT DESCRIPTION

SECTION 1

INSTRUMENT DESCRIPTION

INTRODUCTION

1.1 Purpose

The Model R1L-D1 is a portable microohmmeter designed to
measure low resistances and resistance temperature detectors
(RTD's) with high accuracy. Normally, 4-wire measurements
are utilized in order to eliminate any errors caused by the
lead resistance. Additionally, 2 or 3-wire m easu rements may
be made. Two leads are used to pass a regulated current
through the resistance under test in series with an internal
precisi on calibrat ed resistor. T wo separate l eads are us ed to
measure the voltage drop across the external resistor; this
voltage is then compared with the voltage drop across the
internal resistor. The value of the external resistor is then
calculated from the ratio of these two voltage readings. A
microprocessor, with TEGAM proprietary firmware functions,
performs all calculations such as range selection, display
information etc.

1.2 Performance Characteristics

This is an automatic range-selection instrument, wi th manual
over-ride of one range step.

Range

Full

Scale (Ω)

Resolution

(Ω)

Test Current

Peak (mA)

1

0.199999

1 µ

50

2

1.99999

10 µ

50

3

19.9999

100 µ

50

4

199.999

1 m

0.5

5

1999.99

10 m

0.5

Table 1: Ranges

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INSTRUMENT DESCRIPTION

Accuracy:

Accuracy of all resistance measurements are affected by the
test leads unless 4-wire Kelvin measurement connections a re
used.

Range

Full

Scale

(Ω)

4-Wire

Kelvin

3-Wire

2-Wire

Test

Current

1

0.199999

±0.05%

±15 LSD*

Not

Specified

Not

Specified

50 mA

2

1.99999

±0.05%

±2 LSD*

Not

Specified

Not

Specified

50 mA

3

19.9999

±0.05%

±1 LSD*

Not

Specified

Not

Specified

50 mA

4

199.999

±0.05%

±1 LSD*

±0.05%

±1 LSD*

±0.05%

±1 LSD*1

0.5 mA

5

1999.99

±0.05%

±1 LSD*

±0.05%

±1 LSD*

±0.05%

±1 LSD*1

0.5 mA

*LSD= Least Significant Digit

1

Does not include test lead or contact resistance

Table 2: Specifications

When making low resistance measurements, variables such
as test lead resistance, contact resistance of all the
connections, as well as ambient temperature will affect the
measurement accuracy. When using 4-wire connections,
these effects are minimized.

When making 2 and 3-wire measurem ent s, ev en if all the t est
leads are of known value, the variables of temperature and
contact resistance remain unpredictable and will add to the
uncertai nty of the mea surement. Th e R1L-D1 accuracy is not
specified for 2 and 3-wire mode on ranges 1 t o 3. This does
not mean that the R1L-D1 cannot be operated in these
ranges, but the user needs to be aware of the issues and
compensate for the variables that affect measurement
accuracy outside of the instrument. Errors that can be
introduced at these resistance levels will likely result in
measurement accuracies beyond t he intrinsic accuracy o f the
R1L-D1. Therefore the accuracy specification is not given.

3-wire operation balances the resistance of one lead against a
second l ead, compensati ng for the lead resi stance as long as
the leads are identical. Therefore in 3-wire mode, the test
leads and their connections must be of identical resistance

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INSTRUMENT DESCRIPTION

and composition or the measurement accuracy will be
negatively affected.

Operating an ohmmeter with two wires results in lead
resistance, which is in series with the resistor under test,
being added to the unknown resistance. Further, copper wire
resistance has a large temperature coefficient. Two leads of
relatively heavy 18 gauge wire, each 8 feet long, will add
approximately 0.1 Ω to the measured value. Therefore, 2-
wire operation should not be used with low-value resistors,
without subtracting the resistance of the test leads.

Note that the R1L-D1 is a 5 ½ digit instrument in order to
provide 10 mΩ resolution when reading 1060 Ω RTD's. On
lower ran ges, t his provid es fin er res olu tion, down t o 1 µΩ on
the 0.1 Ω range. However, with a maximum of 50 mA of test
current, the voltage signal for 1 µΩ is only 0.05 µV, easily
obscured by noise picked up in the leads. Thus, it should not
be expected to read one count accurately on the low
resistance ranges

.

This uni t will operate ov er a temp eratur e rang e from 0 t o 50
°C. This unit will comply with the requirements of MIL-PRF­28800 Class 3 for shipboard applications.

1.3 Description of Equipment

Physical: A rugged heavy-duty case is provided to contain
and protect the instrument. When closed, a gasket seals the
lid to protect the instrument against water and dirt while the
instru ment is carried th rough rainstorm s or other haz ardous
conditions. When the lid is open, for operation of the
instrument, a second gasket provides additional, although
reduced, protection. Feet are molded into the bottom of the
case and projections provide for stacking several units high
during temporary storage.

Dimensions: 356 mm (14”) x 269 mm (11”) x 153 mm (6”).
Weight is 3.6 kg (8 lb). With the lid open for operation, the
front panel and its controls are readily accessible. Controls

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INSTRUMENT DESCRIPTION

and connectors are of a size and spacing such that the
instrument may be operated while wearing safety gloves.

Electrical: Power is from five rechargeable Ni-Cad C-cells,
rated at 3000 mA-hours each, series-connected. Nominal
voltage is 1.2 V each, totaling 6.0 V. Current drain varies
with range and back-lighting; but is approximately 20 mA
with no connection, providing approximately 140 hours of
operation when fully charged. To charge the battery, check
that the mains input module is set to the correct voltage,
plug the line cord into the front panel AC receptacle, with the
other end connected to a source of AC power. See Section

2.2. The battery will be charged (from a discharged
condition) in less than 8 hours; no damage will occur if
charged for a longer period. Charging power consumption
from nominal AC power line is less than 10 W average. Th is
instrument may be operated while connected to the AC line
without damage.

Front Panel Controls and Displays (See Figure 1)

MODE pushbutton

, is used t o select 4-wire, 3-wire, or 2-wire
operati on. When p ower i s first tu rned on, th e default i s to 4­wire operation. Successive operations of this pushbutton will
step the unit through 3-wire and 2-wire operation, then back
to 4-wire operation. Note that this is indicated on the display
by a 4, 3, or 2, at the left end of the display.

RANGE pushbutton. Note that the R1L-D1 selec ts the proper

range automatically, but the RANG E pushbutton may be used
to step through all five ranges, plus auto -range, manually.

BACK-LIGHT pus hbutton. One operati on turns the back-light

of the display on. A second operation tur ns the back-light off.

POWER pushbut ton (alternate action). One operation to turn

the pow er on, and a s econd operati on to turn th e power off.
Note that the display may be used as an indication that
power is on.

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INSTRUMENT DESCRIPTION

DISPLAY is a 16 character alphanumeric back-lit LCD. The

first character, a 2, 3 or 4 indicates 2, 3 or 4-wire
measurement. The next four characters will normally be
"WIRE"; however, they will also read "OVER", if over-range,
or "BATT", for low battery voltage. The sixth character is
either blank or an asterisk, which indicates auto-range. The
next seven characters display the resistance reading (six
digits and the decimal point). Note that while auto-ranging,
this block of characters will read "RANGE". The final
characters (to the right) display the Ω symbol, with the
prefix k or m, as required for kΩ or mΩ.

Note that although the front panel lists the two lowest
ranges as 0.2 and 2 Ω for the sake of simplicity, the display
shows them as 200.000 and 2000.00 mΩ. Also, as is t ypical
of digital voltmeters, full scale readings are rounded off as
2xxx, but actual full-scale readings are 1.99999, etc.

A front panel LED marked "AC POWER" indicates that AC
power is connected.
A front panel LED marked "BATTERY CHARGING" indicates
that the battery is in fast charge mode. If the unit is
connected to AC power and this LED is not on, the Batteries
are in trickle charge mode.

Four binding posts for connection of test leads are marked

+I, +E, -E, and -I. Proper connections to the resistor under
test are described in Section 2.2 below.

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INSTRUMENT DESCRIPTION

Figure 1: Front Panel Layout

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INSTRUMENT DESCRIPTION

1.4 List of Items Furnished

1 each Model R1L-D1 with power cord
5 each NiCad battery cells.
1 each Instruction Manual.

1.5 Tools and Test Equipment Required for Maintenance

Solderi ng iron , solder, Phillips No. 1 & 2 screwdriver and
a small flat-bladed screwdriver.
Test equipment: See Section 4.3 below.

1.6 Storage and Shipping Requirements

The R1L-D1 should be stored in a relatively dust free
environment.
Temperature: -40 to +71 °C.
Relative humidity: 0 to 100%, non-condensing.
See Section 4.7 below for shipping requirements.

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2-1

PREPARATION FOR USE AND INSTALLATION

SECTION 2

PREPARATION FOR USE AND INSTALLATION

2.1 Unpacki ng an d Inspection

Upon receipt, the R1L-D1 should be carefully unpacked and
removed from the shipping container. Separate the units
from the packing material and inspect both the instrument
and the accessory kit for any external damage.

• If any dents, broken, or loose parts are seen, do not use

the equipment. Notify TEGAM immediately.

2.2 Preparation for Use

• Release th e tw o l at ches wh i ch secu re th e li d of th e Mod el
R1L-D1, and open t h e lid. Since the lid i s w ell gas keted,
it may be difficult to open if there is an appreciable
difference between internal and external air pressure.

• Note that the instrument is shipped with its battery
removed. U nw rap the fi ve N i Cad C -cel l s which comp ri se
the battery.

• Inspect the MAINS power entry module and make sure
that it indicates the proper voltage for the MAINS to be
used (120 or 240 VAC).

MAINS Setup

If the mains voltage is not correct, proceed as follows:
a. Pry the top of the MAINS cover open by inserting a flat

bladed tool at the top of the module just down from the
mains terminals.

b. Remove the fuse assembly and replace the fuse with the

correct one .
For 115 VAC operation: FU-203; Bussman AGC 0.5 A /
Littelfuse 0312.500 (Fast Blow)
For 230 VAC operation: FU-1804-2; Bussman GDC 0.25 A
/ Littelfuse 0218.250 (Slow Blow)
The single 1/4"x1.25" 0.5 A 120 V fu se goes on one side