Megger DLRO10HD Data sheet

10 A Digital Low Resistance Ohmmeter

DLRO10HD

10 Amp Digital Low Resistance

n High or low output power selection for

condition diagnosis

n Rechargeable battery or line power supply,

continuous operation, even with dead
battery

n 10 A for 60 seconds, less time waiting to

cool, great for charging inductance

n High input protection to 600 V, inadvertent

connection to line or UPS voltage will not
blow a fuse

n Heavy duty case: IP 65 lid closed, IP54

operational (battery operation only)

n Rotary switch selects one of five test

modes, including auto start on connection,
giving ease of use

DLRO10HD

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.

ADDITONAL FEATURES AND BENEFITS

n Rugged case well suited to transportation with shoulder

strap and lead set pouch

n Removable lid facilitates easy test lead connection
n Operational ingress protection is IP 54 (battery power

only) ensuring protection from the elements

n 7Ah lead acid battery provides extended operation and

can be charged whilst operating from line power

n Rotary mode switch with bidirectional (current reversal

with averaging cancels thermal EMFs), unidirectional,
automatic, continuous and inductive modes

n Large, clear LCD display with backlight and contrast

adjustment

n Auto 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.

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.

DLRO10HD

10 A Digital Low Resistance Ohmmeter

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 the supplied DH4 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.

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 2000m (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 90 - 264 V, 50-60 Hz

Charge time 8 hours

Backlight LED backlight

Battery life >1000 Auto (3 sec) tests

Auto power down 300s

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)

Resolution and Accuracy

Test current accuracy ±10%
Voltmeter input impedance >200 kΩ

Test

current

0.1 mA

0.1 mA

1 mA

10 mA

100 mA

1 A

10 A

1 A

10 A

Resistance

range

0 to

2500.0 Ω

0 to

250.00 Ω

0 to

25.000 Ω

0 to

2500.0 mΩ

0 to

250.00 mΩ

0 to

25.000 mΩ

0 to

2500.0 μΩ

0 to

2500.0 mΩ

0 to

250.00 mΩ

Resolution

(as

displayed)

0.1 Ω ±0.2% 25 mV 25 μW

0.01 Ω ±0.2% 25 mV 2.5 μW

1 mΩ ±0.2% 25 mV 25 μW

0.1 mΩ ±0.2% 25mV 250 μW

0.01 mΩ ±0.2% 25 mV 2.5 mW

1 μΩ ±0.2% 25 mV 25 mW

0.1 μΩ ±0.2% 25 mV 0.25 W

0.1 mΩ ±0.2% 2.5 V 2.5 W

0.01 mΩ ±0.2% 2.5 V 25 W

Basic

accuracy*

Full

scale

voltage

* The accuracy stated assumes forward and reverse
measurements.

Max.

power

output

Test leads DH4 lead set included

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.