Megger DLRO-10 User manual

USER GUIDE
GUIDE DE L’UTILISATEUR
BEDIENUNGSANLEITUNG
GUIDA PER L’UTENTE
GUIA DEL USUARIO
M
DLRO®-10 & DLRO®-10X
Digital Low Resistance Ohmmeter

2
GSAFETY WARNINGS
nThese safety warnings must be read and understood before the instrument is used.
nWhenever possible, circuits should be de-energised before testing.
If it is impossible to de-energise the circuit, (e.g. high voltage batteries cannot be switched off while their connections are tested) the user
must be aware of the dangers. The instrument terminals will become live when connected to the circuit. Therefore when used on hazardous
voltages custom Megger DH6 test leads must be used.
nTesting inductive circuits can be hazardous:
After testing an inductive load there will be an amount of energy stored in the inductance. This energy is released in the form of a discharge
current. Disconnecting an inductive load while current is still flowing will cause a high voltage arc, which is a danger to both the user and the
item under test.
Although the DLRO 10 and DLRO 10X are not designed as transfromer ohmmeters the DLRO 10 is fitted with a DISCHARGE lamp, marked
‘I’, which indicates that current is flowing in the C1-C2 loop. This lamp will flash at end of a test on an inductive load while a discharge
current is still flowing and will stop flashing when the current has decayed to less than 1mA. DLRO 10X uses a message on the display to
achieve this.
For testing large inductive resistances the current carrying leads should be connected securely to the item under test before starting the test.
It is not recommended that duplex handspikes be used to carry out tests on inductive loads. If inadvertently using the DH4 handspikes on an
inductive load, the L1 lamp on the handspikes will flash amber while discharge current flows, thereby duplicating the function of the ‘I’ lamp
on the instrument. It is important to maintain contact until the L1 light stops flashing amber and turns green indicating the end of the test.
nThis product is not intrinsically safe. Do not use in an explosive atmosphere.
nPlease note. The neck strap is specifically designed to break if subjected to a strain of approximately 50 kg.
CAT II
Measurement category II: Equipment
connected between the electrical outlets and
the user’s equipment.
CAT III
Measurement category III: Equipment
connected between the distribution panel and
the electrical outlets.
CAT IV
Measurement category IV: Equipment connected
between the origin of the low-voltage mains
supply and the distribution panel.

Safety Warnings 2
General Description 4
General Operation - DLRO 10 5
Test Current Indicators 5
Noise Lamp 5
‘C’ & ‘P’ Indicators 5
‘V’ & ‘I’ Warning Indicators 5
General Operation - DLRO 10X 6
DLRO 10X Top Panel 6
DLRO 10X Main Menu Screen 6
Warning Messages 6
Noise 6
‘C’ & ‘P’ Indicators 6
External Voltage Warning 7
Discharge Current Warning 7
The Menuing System 7
Test Menu 7
Options Menu 7
Retrieve 7
Display 7
Download 8
Passbands 8
Set Clock 8
Delete Data 9
Storage 9
Range Menu 9
Entering Notes In The Memo Screen 10
Test Result Storage 10
Keypad Operation 11
Test Modes 12
Normal Mode 12
Automatic Mode 12
Continuous Mode 12
High Power Mode 12
Unidirectional Mode 13
Test Techniques & Applications 14
Testing Using DH4 Duplex Handspikes 14
Testing Using Handspikes Or Individual Leads. 14
Test Sequence 15
Test Lead Resistance 15
Overheating 15
Battery Module And Care 16
The Battery Module 16
Battery Charging 16
The Battery State Indicator 17
Standard Charging. 17
Slow Charging. 17
Standard Charging But At A Slow Rate. 17
There Is A Temperature Problem. 17
Input Voltage Too Low. 17
Battery Nearly Exhausted 17
Error: Reset 17
Overvoltage Problem
18
Specifications 19
Troubleshooting 21
Repair and Warranty 23
End of life disposal 24
Symbols used on the instrument
G Caution: Refer to accompanying notes
t Equipment protected throughout by Double or
reinforced Insulation (Class II)
c Equipment complies with current EU Directives
Do not dispose of in the normal waste stream
3
CONTENTS

The DUCTER DLRO 10 and DUCTER DLRO 10X make up a family of low resistance ohmmeters that measure resistances in the range from 0.1 µΩ to 2
kΩ. Both instruments provide a maximum test current of 10 Amps d.c. which is automatically selected according to the value of resistance being tested.
The DLRO 10X allows you to override this automatic selection and select your own test current.
The measured value of resistance is output to the instrument display with indication of the units, µΩ, mΩor Ω. The DLRO 10 uses a large LED display
and indicators to display the value and units respectively, while the DLRO 10X contains all the information on a clear backlit LCD display.
The use of a four terminal measurement technique removes the test lead resistance from the measured value and auto current reversal eliminates the
effect of standing voltages across the test sample. Additionally, before and during a test, test lead contact is monitored to further reduce the chance of
erroneous readings.
A resistance measurement takes approximately 2.5 seconds and comprises a measurement with forward current, reverse current and a display of the
average. On the DLRO 10X all three values are displayed, and optionally, the measurement may be limited to forward current only.
The instrument is powered by a rechargeable Nickel Metal Hydride (NiMH) battery, which permits one thousand 10 Amp tests to be completed on a
single charge. The battery module contains intelligent circuitry, which prevents damage to the battery from overcharging, and a battery state indicator.
A removable lid that is hinged at the back and held closed by magnetic catches covers the top panel. This lid may be removed if required by opening
fully and snapping out of its hinges.
Both instruments are protected against accidental connection to external voltages up to 600 V d.c. applied between any pair of the four terminals
for up to 10 seconds. Please note that applying 600 V to the potential terminals will cause some internal heating. Expect errors of up to 30 digits
immediately after the application of such voltage. Full accuracy will be restored within two to three minutes. Both instruments are supplied complete
with a pair of DH4 Duplex Handspikes with 1.2 m leads. Other lengths and terminations are available if required.
GENERAL DESCRIPTION
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Press the On/Off switch to turn DLRO 10 on. All lamps will light, V and
I lamps will flash, the software version will be displayed and the Ωlamp
will light. If the test leads have not been connected to the test sample
the ‘C’ and ‘P’ lamps will also light. Press the On/Off button again to
turn the instrument off. If the instrument is not used for 5 minutes it will
be turned off automatically.
Adjust the brightness control to a comfortable level.
Select the Test mode by pressing the Mode button repeatedly. The
indicator lamps will cycle through the various Test modes in turn (see
the section on Test modes). Press the Test button to start a test.
Test Current Indicators
The test current is selected automatically by DLRO 10 and is indicated
by the lamps on the left of the panel. The measured value is displayed
in the main window and the units (µΩ, mΩor Ω) are shown by the
lamps to the right of the window.
Noise Lamp
Noise in excess of 100 mV 50/60 Hz will light the ‘Noise’ lamp and
measurement accuracy cannot be relied upon.
‘C’ & ‘P’ Indicators
The ‘C’ lamp illuminates to indicate contact failure in the ‘C1-C2’ loop.
The ‘P’ lamp illuminates when there is a break in the P1-P2 loop.
‘V’ & ‘I’ Warning Indicators
If external voltage is applied to the terminals the ‘V’ lamp will flash. This
is a warning that the item under test is live and might be dangerous. A
test cannot be performed in this condition.
The ‘V’ lamp will light if more than 50 V. is applied between either
voltage terminal and a current terminal. If the voltage appears between
just the voltage terminals or just the current terminals the lamp will light
at 100 V peak or 5 V peak respectively.
Please note - The ‘V’ lamp will only indicate if a voltage appears
between terminals. The lamp will not operate if all terminals
are at the same high voltage. The lamp will not operate if the
instrument is turned off.
The ‘I’ lamp will light if a current greater than 1 mA is still flowing after
a test is completed. This suggests that an inductive load has been tested
and is still discharging. Do not disconnect the current loop until the ‘I’
lamp has gone out.
GENERAL OPERATION - DLRO 10
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DLRO 10X Top Panel
All the controls needed to set up and operate DLRO 10X are located on
the top panel of the instrument.
To the left of the large LCD display are the controls for moving around
the display, controlling the menuing system and adjusting the display
contrast and backlight.
To the right of the display is the large Test button, Power On/Off button
and an alphanumeric keypad for entering notes relating to a test which
will be stored with the test results for later reference.
To turn your DLRO 10X on, press the On/Off button for approximately
1 second. Press again to turn the instrument off. If the instrument is not
used for 5 minutes it will be turned off automatically.
DLRO 10X Main Menu Screen
When first switched on DLRO 10X displays a copyright screen, followed
by the Main Menu screen.
This screen provides you with information such as percentage of battery
charge remaining, index number of the next test, number of tests already
stored and the current date and time.
This screen also provides access to the menuing system, through which
you set up your instrument and choose the desired test parameters.
Navigation of this menuing system is by means of the cursor control and
Enter key.
Warning Messages
The Main Menu screen will from time to time also contain certain
warning messages
Noise
Noise in excess of 100 mV 50/60 Hz will activate the message ‘Noise’
at the bottom of the display. Above this level accuracy cannot be relied
upon.
‘C’ & ‘P’ Indicators
A good measurement requires both the current carrying circuit and the
voltage detection circuit to be completed by the item under test. DLRO
10X checks for this continuity. If there is poor continuity in either circuit
a message will appear at the bottom of the display. This will read “P
OPEN CIRCUIT” if the voltage contacts are high resistance, “C OPEN
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GENERAL OPERATION - DLRO 10X

CIRCUIT” if the current circuit is not made or “CP OPEN CIRCUIT” if
both circuits are inadequate. Check the contacts, since a measurement
cannot be made if any of these messages is visible on the display.
External Voltage Warning
If external voltage is applied to the terminals a message “EXT VOLTS”
will flash on the display. This is a warning that the item under test is live
and might be dangerous. A test cannot be performed in this condition.
The “EXT VOLTS” message will flash if more than 50 V. is applied
between either voltage terminal and a current terminal. If the voltage
appears between just the voltage terminals or just the current terminals
the message will appear at 100 V peak or 5 V peak respectively.
Please note - The message will only appear if a voltage appears
BETWEEN terminals. The message will not appear if all terminals are at
the same high voltage. The message will not operate if the instrument is
turned off.
Discharge Current Warning
A message CURRENT FLOW will appear if a current greater than 1 mA is
still flowing after a test is completed. This suggests that an inductive load
has been tested and is still discharging. Do not disconnect the current
loop while the discharge warning is showing.
The Menuing System
Use the Left and Right arrows of the cursor control to highlight the menu
required. Press the Down cursor control to see the options available
on that menu. Select the required option using the cursor control and
press Enter to set that option. Depending on the menu item selected
the display will either present further options or will return to the main
menu screen.
Test Menu
This sub-menu selects the test mode. Only one mode can be active at
a time and the active mode is displayed below the heading TEST. (See
Test Modes later in this manual for details of each mode.)
Options Menu
The Options menu has five options that are not related to each other, as
shown below.
Retrieve
allows the recall of stored results to the display or a PC.
Display
recalls each test, in sequence, to the instrument display
starting with the latest stored result.
Use the cursor control Up and Down controls to step later or earlier
respectively through the stored results. Alternatively, if you know the
index number of the test you wish to display, type the number on the
keypad and press Enter.
An asterisk (*) next to the word “MEMO” means that there are notes
attached to this result. Press the right cursor control to view the notes.
GENERAL OPERATION - DLRO 10X
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Download
causes the entire contents of the data store to be output
to the RS232 port to the left of the display. A copy of
AVO Download Manager, which facilitates downloading
and formats the data, is supplied.
Downloading data does not cause the stored data to be
erased from memory. To clear data from memory see
“Delete Data” below.
Please note - DLRO 10X also makes data available via the RS232 Port
in real time and is suitable for printing on a self-powered serial printer.
The output has the following form:
TEST NUMBER
TEST TYPE
DD MM YY HH MM
01/01/00 00:33
FORWARD RESISTANCE
REVERSE RESISTANCE
AVERAGE RESISTANCE
SELECTED CURRENT
UPPER LIMIT
LOWER LIMIT
PASS/FAIL
The last three lines will only appear if passbands have been set
Passbands
This option allows you to set upper and lower limits between which the
test result average must fall if it is to be signalled as a Pass (a long tone
from the buzzer). Readings outside these limits will be signalled as a Fail
(a short tone from the buzzer).
Values are entered via the keypad complete with decimal points, where
applicable, and including µ or m (See section on the Alphanumeric
Keypad). It is not necessary to enter the Ωsymbol. The upper limit must
be less than or equal to 2000.0 Ωand the lower limit must be less than
the upper limit.
After completing the upper limit press Enter. DLRO 10X will check that
valid numbers have been entered and will move to the lower limit.
Complete this limit and press Enter. DLRO 10X will check that valid
numbers have been entered and will display the option to ENABLE or
DISABLE the passbands.
Highlight your choice and press Enter. You will return to the Main Menu
screen.
Note: Passbands will remain enabled or disabled until you enter this
screen and change the selection. If all that is required is to change Pass-
bands from ENABLED to DISABLE or vice versa, enter the PASSBAND
screen and press Enter until the ENABLED / DISABLED choice is shown
at which time you may change the selection.
Set Clock
This option sets the real time clock date and time settings as well as
setting the date format. When you enter this screen the current date,
time and date format will be displayed.
Use the cursor control Up and Down arrows to adjust the highlighted
data. Step to the next item by using the Right cursor control arrow.
GENERAL OPERATION - DLRO 10X
8

The row below DD MM YY HH MM contains respectively the date, the
month, the two-digit year, the hour of the day in 24-hour notation and
the minute. These must be entered in this sequence regardless of the
date format you wish to use.
The lower DD/MM/YY shows the current date format. Pressing the
cursor control Up arrow will cycle through the available options DD/
MM/YY, MM/DD/YY or YY/MM/DD.
The bottom line shows the current setting of date and time. This is
updated when you press Enter to exit the Set Clock function. However,
tests already stored prior to changing the date format will retain the old
format.
Delete Data
Select Delete Data if you wish to clear DLRO 10X’s memory of stored
data. In case you have selected this Option by accident you will be
asked to confirm that you wish to delete the data; the default is NO.
Change this to YES and press Enter if you wish to delete all data.
Please note - ALL stored data will be deleted.
Storage
The Storage option sets the default for data storage. It may be set to
always store data or never to store data. Highlight the desired option at
the bottom of the screen and press Enter.
With the exception of tests carried out in Continuous mode, at the end
of each test you have the option to change the default by selecting
STORE or NO STORE at the bottom of the results screen.
At the end of a test, if memory is full this STORE / NO STORE message
will change to MEMORY FULL and no more tests will be stored.
Data is stored indefinitely if a charged battery pack is fitted. If the main
battery becomes exhausted or is removed, data is maintained for a
period of 4 days by an internal backup battery. When a charged battery
pack is refitted, the backup battery will recharge to full capacity within
1 week.
Range Menu
DLRO 10X uses a test current between 100 µA and 10 A to measure the
resistance of the item under test. If set to AUTO, DLRO 10X will select
the current according to the resistance it detects. (see Specifications,
Ranges)
However, in some cases it may be desirable set a maximum test current.
If this is so, move the cursor to the desired current and press Enter.
Six test currents are available; 10 A, 1 A, 100 mA, 10 mA, 1 mA and 100
µA. Selecting the 10 A maximum will have the same effect as selecting
AUTO.
The Main Menu screen will show the active current range beneath the
RANGE heading.
ENTERING NOTES IN THE MEMO SCREEN
At the end of each test, (with the exception of a test in Continuous
mode), you can select the STORE or NO STORE option to store the test
GENERAL OPERATION - DLRO 10X
9
TEST OPTIONS RANGE
NORM AUTO
DD MM YY HH MM
09/10/00 15.08
DD MM YY
09/10/00 12.02

results or not. Select the desired option using the cursor control. This
overrides the default setting under Options, Storage for one test only.
If you wish to add comments to the test results, instead of pressing
Enter, briefly press one of the twelve keys on the keypad. You will
enter a memo screen that allows you to enter up to 200 characters of
alphanumeric information concerning the test. When you have entered
all information press Enter and the measurement and memo will be
stored regardless of whether STORE or NO STORE was selected.
If you do not wish to add notes and are happy to accept the default
STORE / NO STORE setting you may press the Test button and a new
test will be started.
TEST RESULT STORAGE
Each test is numbered, starting at test 1. This test number is incremented
automatically, as each result is stored. The test result memory can store
a maximum of 700 tests, each being identified by its test number, date
and time.
It is advisable to retrieve all data to a PC and then to delete all data
before the test number reaches this maximum. Deleting the data will
reset the test number to 1. This will save loss of data.
KEYPAD OPERATION
The 12 key keypad is similar to those used on mobile telephones in that
each key is capable of producing one of several characters depending
on the number of times the key is pressed.
The keypad is used to enter data into the Memo field.
Pressing the blue key marked 9/A changes the function of the keyboard
between alpha and numeric modes.
In alpha mode a full height flashing vertical bar (|) indicates the cursor.
The keys 2 to 9 will produce the letter shown on the keys depending on
the number of presses. For example if the 2 key is pressed once an ‘A’
will appear, twice and a ‘B’ will appear etc.
The 0 key produces a space.
The 1 key is a destructive backspace.
In numeric mode a half height flashing bar (‘) indicates the cursor. The
keys marked 1 - 9 and 0 produce that number when pressed. Press the
respective key briefly to enter the desired number. Pausing will cause
the cursor to move on to the next character. If a key is held down it will
auto-repeat.
The key at the bottom right hand corner of the keypad marked with a
dot is a special key that produces 20 special symbols. Each press will
sequentially produce the character shown on next page:
GENERAL OPERATION DLRO 10X
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