Megger DLRO10HD User manual

■NEW interchangeable test lead terminations
■High or low output power selection for
condition diagnosis
■Rechargeable battery or line power supply,
continuous operation, even with dead
battery
■10 A for 60 seconds, less time waiting to
cool
■Protected to 600 V without blowing a fuse,
test lead live voltage warning light
■Heavy duty case: IP 65 lid closed, IP54
battery operation
■Simple rotary switch selection of five test
modes, including auto start on connection
DLRO10HD
10 A Digital Low Resistance Ohmmeter
DLRO10HD
10 Amp Digital Low Resistance
DESCRIPTION
Augmenting Megger’s DLRO10 and 10X range the DLRO10HD
combines ultimate simplicity of operation with a rugged IP65
case designed for stable ground and bench operation.
The unit is powered from either its rechargeable battery or line
power making it suitable for continuous testing in production
line/repetitive use environments.
Rotary switch controls are simple and easy to operate in all
weather conditions and with gloved hands. A large, clear,
backlit LCD display is easy to read from a distance. The
DLRO10HD provides significantly enhanced compliance and
is capable of delivering 10 A into measurements up to 250
mΩ and 1 A into measurements up to 2.5 Ω. The duration of
each test may be up to 60 seconds.
The DLRO10HD is rated CATIII 300 V provided the optional
terminal cover is fitted to the instrument. Details of which can
be found in the ordering information panel of this data sheet.
The DLRO10HD provides five test modes each of which is
selected through a simple rotary control.
History of ‘Ducter’ testing
For over 100 years the ‘Ducter test’ has been used to describe
a simple test for measuring very low contact resistances
and “Ducter”, which is still used as a trade mark, was the
name originally given to the low resistance ohmmeter
manufactured by Megger. The name Ducter was registered
by Megger in June 1908 and ‘Ducter’ has since become the
industry standard.
ADDITONAL FEATURES AND BENEFITS
nRugged case well suited to transportation with shoulder
strap and lead set pouch
nRemovable lid facilitates easy test lead connection
nOperational ingress protection is IP 54 (battery power
only) ensuring protection from the elements
n7Ah lead acid battery provides extended operation and
can be charged whilst operating from line power
nRotary mode switch with bidirectional (current reversal
with averaging cancels thermal EMFs), unidirectional,
automatic, continuous and inductive modes
nLarge, clear LCD display with backlight and contrast
adjustment
nAuto power off function conserves battery
APPLICATIONS
The DLRO10HD measures low resistance values in applications
ranging from railways and aircraft to resistance of components
in industry.
Any metallic joint can be measured but users must be aware
of measurement limitations depending on application. For
example, if a cable manufacturer plans to make resistive
measurements on a thin wire, a low test current should be
selected to prevent heating the wire thereby changing its
resistance

2
DLRO10HDX
10 A Digital Low Resistance Ohmmeter
Measurements on electric motors and generators will be
inductive and require the user to understand the inductive
mode and charging process before a correct result is achieved.
The DLRO10HD is well suited to measuring thick conductors,
bonds and quality of welding because of its 10 A range for
resistance values up to 250 mΩ.
Electromagnetic noise induced into the leads can interfere
with a reading. A noise symbol alerts the user and prevents
a measurement when the instrument detects noise above its
threshold.
When dissimilar metals are joined a thermocouple effect is
created. Users should select a bidirectional mode to ensure
cancellation of this effect. The instrument measures with
current flowing in both directions and averages the result.
Normal mode is initiated by pressing the ‘Test’ button after
connecting the test leads to the unit under test. Continuity
of all four connections is checked. Current is applied in both
forward and reverse direction following which measurement
is displayed.
Automatic mode is started as soon as the probes make contact.
Forward and reverse current measurements are made and the
average value is displayed. This mode is ideal when working
with handspikes. Each time the probes are removed and
reconnected to the load a new test will be performed without
the need to press the test button.
TEST modes
Automatic unidirectional mode applies current in one
direction only to speed up the measurement process.
However thermal EMF resulting from dissimilar metal bonds
can cause lower accuracy. Test starts automatically when
probes are connected.
Continuous mode allows repeated measurements to be made
on the same sample. Simply connect the test leads and press
the test button. The measurement is updated every three
seconds until the circuit is broken.
Inductive mode is selected when measuring resistance on, for
example, motors and generators. When measuring inductive
loads it is necessary to wait for the voltage to stabilise as the
inductive element is charged. Test leads are firmly connected
to the device under test and the ‘Test’ button pressed. The
instrument will pass the selected current through the sample
continuously in one direction only and take repetitive readings
that will gradually decrease to the true value as the voltage
stabilises. The operator decides when the result is stable and
presses the ‘Test’ button to terminate the test.
ELECTRICAL SPECIFICATIONS
Resistance/Current Ranges
The green resistance ranges on the keypad indicate low
output power (<0.25 W) outputs. Red ranges indicate higher
2.5 W (1 A) and 25 W (10 A) power outputs.
Resolution and Accuracy
Test current accuracy ±10%
Voltmeter input impedance >200 kΩ
Test
current
Resistance
range
Resolution
(as
displayed)
Basic
accuracy*
Full
scale
voltage
Max.
power
output
0.1 mA 0 to
2500.0 Ω 0.1 Ω ±0.2% 25 mV 25 μW
0.1 mA 0 to
250.00 Ω 0.01 Ω ±0.2% 25 mV 2.5 μW
1 mA 0 to
25.000 Ω 1 mΩ ±0.2% 25 mV 25 μW
10 mA 0 to
2500.0 mΩ 0.1 mΩ ±0.2% 25mV 250 μW
100
mA
0 to
250.00 mΩ 0.01 mΩ ±0.2% 25 mV 2.5 mW
1 A 0 to
25.000 mΩ 1 μΩ ±0.2% 25 mV 25 mW
10 A 0 to
2500.0 µΩ 0.1 μΩ ±0.2% 25 mV 0.25 W
1 A 0 to
2500.0 mΩ 0.1 mΩ ±0.2% 2.5 V 2.5 W
10 A 0 to
250.00 mΩ 0.01 mΩ ±0.2% 2.5 V 25 W
* The accuracy stated assumes forward and reverse
measurements.
Inductive mode or undirectional mode will introduce an
undefined error if an external EMF is present.
Basic accuracy at reference conditions.
GENERAL SPECIFICATIONS
Temperature coefficient < 0.01% per ºC, from 5 ºC to
40 ºC
Maximum altitude 2000 m (6562 ft) to full safety
specifications
Display size/type Main 5 digit + 2 x 5 digit
secondary displays
Battery type 6 V, 7Ah sealed lead acid
Voltage input range 100 - 240 V 50 / 60 Hz 90 VA
Charge time 8 hours
Backlight LED backlight
Battery life >1000 Auto (3 sec) tests
Auto power down 300s

3
DLRO10HDX
10 A Digital Low Resistance Ohmmeter
OPTIONAL TERMINAL COVER
The CATIII 300 V rating
on the DLRO10HD is only
valid when the instrument
is fitted with the optional
terminal cover to provide
the required creepage and
clearances at the instrument
terminals. Although the
terminal cover may be used
with any test leads, only the Megger DH4, DH5 and DP1-C
duplex handspikes, and KC2-C insulated kelvin clips have
suitable probe insulation to comply with the requirements of
IEC61010-1 and the CATIII 300 V rating.
Mode selection Rotary switch
Range selection Rotary switch
Weight 6.7 kg
Case dimensions L315 mm x W285 mm x
H181 mm
Pouch for test leads Yes (lid mounted)
Test leads DH4C lead set
IP rating IP65 case closed,
IP54 battery
operation
Safety rating
In accordance with IEC61010-1, CATIII 300V when used
with optional terminal cover (details in ordering information)
Operating temperature and humidity
-10 °C to +50 °C
(14 °F to 122 °F) <90% RH
Reference conditions 20 °C ±3 °C
Storage temperature and humidity
-25 °C to +60 °C, <90% RH
EMC
In accordance with IEC61326-1 (Heavy industrial)
Noise rejection
Less than 1% ±20 digits additional error with 100 mV peak
50/60 Hz. on the potential leads. Warning will show if hum
or noise exceeds this level.
Maximum lead resistance
100 mΩ total for 10 A operation irrespective of battery
condition.
SUPPLIED LEADSET OPTIONS
DLRO10HD
+ KC1 Kelvin clip 3 m leads
+ No test leads supplied
+ DH4-C probe 1.5 m leads

SALES OFFICE
Megger Limited
Archcliffe Road Dover
CT17 9EN England
T [phone]
E [e-mail]
DLRO10HD_DS_en_V07
www.megger.com
ISO 9001
The word ‘Megger’ is a registered trademark
DLRO10HDX
10 A Digital Low Resistance Ohmmeter
ORDERING INFORMATION
Item (Qty) Order No.
DLRO10HD + DH4-C probe 1,5m leads 1006-603
DLRO10HD + KC1 kelvin clip 3m leads 1006-604
DLRO10HD without test leads supplied 1006-657
Standard included accessories
Test lead pouch (lid mounted) 1005-623
DLRO10HD user guide CD 1000-869
Warranty book. 6170-618
Test leads supplied with instruments
1006-603 DLRO10HD = DH4-C probe 1,5m leads 1006-444
1006-604 DLRO10HD = KC1 kelvin clip 3m leads 1006-462
1006-657 DLRO10HD = No test leads supplied 1006-657
Optional Accessories at extra cost
Calibration Shunt,10 Ω, current rating 1 mA. 249000
Calibration Shunt, 1 Ω, current rating 10 mA. 249001
Calibration Shunt, 100 mΩ current rating 1A. 249002
Calibration Shunt, 10 mΩ current rating 10 A. 249003
Certificate of Calibration for Shunts, NIST CERT-NIST
Replacement tips for DH4 and DH5 handspikes.
Needle point 25940-012
Replacement tips for DH4 and DH5 handspikes.
Serrated end 25940-014
Optional Test Leads at extra cost
Normal test leads not fitted with in-line connector:
Duplex Leads
DH5 straight duplex handspikes (2).
One has indicator lights. 2.5m/8ft 6111-517
Terminal cover (use in conjunction with DH4 test leads supplied as
standard, or optional DH5 test leads for CATIII 300 V
compliance) 1002-390
Duplex Handspikes (2) with spring loaded helical contacts.
2m/7ft 242011-7
DH1 2.5m/8ft 6111-022
DH1 5.5m/18ft 242011-18
DH2 6m/20ft (only 1 lead supplied) 6111-023
DH2 9m/30ft (only 1 lead supplied) 242011-30
DH3 9m/30ft 6111-024
Straight Duplex Handspikes (2) Heavy Duty with fixed contacts.
2m/7ft 242002-7
Straight Duplex Handspikes (2) Heavy Duty with fixed contacts
5.5m/18ft 242002-18
Item (Qty) Order No.
Straight Duplex Handspikes (2) Heavy Duty with fixed contacts
9m/30ft 242002-30
Duplex Heavy Duty 5cm (2”) C-Clamps. (2)
2m/7ft 242004-7
Duplex Heavy Duty 5cm (2”) C-Clamps. (2)
5.5m/18ft 242004-18
Duplex Heavy Duty 5cm (2”) C-Clamps. (2)
9m/30ft 242004-30
Duplex handspikes with replaceable
Needle Points 2m/7ft 242003-7
Duplex 1.27 cm (1/2 “) Kelvin Clips. (2)
gold plated 2m/7ft 241005-7
Duplex 1.27 cm (1/2 “) Kelvin Clips. (2)
silver plated 2m/7ft 242005-7
Duplex 3.8 cm (11/2”) Kelvin Clips. (2)
2m/7ft 242006-7
Duplex 3.8 cm (11/2”) Kelvin Clips. (2)
5.5m/18ft 242006-18
Duplex 3.8 cm (11/2”) Kelvin Clips. (2)
9m/30ft 242006-30
Single handspike (1) for potential measurement.
2m/7ft 242021-7
Single handspike (1) for potential measurement.
5.5m/18ft 242021-18
Single handspike (1) for potential measurement.
9m/30ft 242021-30
Current clip (1) for current connections.
2m/7ft 242041-7
Current clip (1) for current connections
5.5m/18ft 242041-18
Current clip (1) for current connections
9m/30ft 242041-30
Note: For more details of optional leadsets see separate test lead
datasheet DLRO_TL_DS_en_V01.pdf
Test leads fitted with inline connector:
Add the part numbers of the complete lead sets and refer
customers to the test lead data sheet for the individual parts
For detailed information on connecting lead accessories refer
to the supplied “accessory important information sheet”
(DLROTestLeads--2007-431_UG_EN-DE-FR-ES-IT_V02)