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DLRO10 and DLRO10X
16
DLRO 10 and DLRO 10X (no passbands)
Lamp L1
Lamp L2
Meaning
Red
Off
Inadequate contact at C and/or P
contacts
Flashes Red
Off
Voltage present between contacts
(DLRO10 Only)
Off
Green
Current less than 1 mA and test
complete.
DLRO10X ONLY if pass bands set
Lamp L1
Lamp L2
Meaning
Off
Green
Measurement Pass
Off
Red
Measurement Fail
6.2 Testing Using Duplex Handspikes Or Individual Leads
Connect the four leads as shown.
If using Duplex Handspikes ensure that the probe marked P is inside the C probes.
Note: When used on hazardous voltages Megger DH6 test leads must be
used.
6.3 Test Sequence
Pressing the TEST button starts the test sequence.
Contact resistance is checked by passing 100 μA through the C1-C2 loop and
checking that the voltage is less than 4 V. Then passing 80 μA through the P1-P2
loop and checking that the voltage is less than 250 mV. If either value is exceeded the
respective lamp or warning message will be displayed.
When all faults have been rectified the test current is increased until the voltage on
P1-P2 is within the 2 mV to 20 mV range. This current is then applied in a forward
and then reverse direction to obtain two measurements.
Both measurements are displayed by DLRO 10X along with the average, while the
DLRO 10 displays the average only.
If the combined resistance of the current leads and test sample is greater than 100
mΩ, testing at 10 A will not be possible.
A 1.9 mΩ resistor will then be tested at the next lowest current (1 A) and the result
will be shown as 1.900 mΩ instead of 1.9000 mΩ.
6.4 Test Lead Resistance
For testing at 10 A, the combined resistance of the current leads must not exceed
100 mΩ. This will ensure that the voltage drop in the leads is less than 1 volt and will
enable 10 A testing under worst case conditions. If you wish to limit test current to no
more than 1 A, on DLRO 10 use current leads with a resistance of about 1 Ω, or on
DLRO 10X select 1A as the maximum test current on the RANGE submenu.
6.5 Overheating
When performing rapidly repeated tests at 10 A, using current leads with a combined
resistance of 100 mΩ, 10 W of heat will be dissipated in the leads and 30 W
within your instrument. If the ambient temperature is high this will cause internal
overheating and the message “hot” will appear on the instrument display and testing
will be halted.
After a few minutes to cool down, testing will be allowed to continue.
If this is a persistent problem, use current leads with a higher resistance (e.g. 200 mΩ
to 300 mΩ). This will reduce the generation of internal heat.
