6
OPERATION
Please note that if your DLRO600 is inadequately grounded / earthed it will
not be possible to start a test.
TEST Menu
The TEST menu allows the selection of one of three test modes - Normal,
Automatic or Continuous. Only one mode can be active at a time and the
active mode is displayed below the heading TEST when you return to the
MAIN MENU screen.
Normal Mode
Normal mode makes a single measurement of the resistance of the sample
under test.
Please note that in this mode both the current and voltage leads must be
connected across the test sample before the Test button is pressed. When
the TEST button is pressed DLRO600 will check for good contact in the P
circuit. If the P circuit continuity is faulty the display will show “POTENTIAL
FAIL”. Press the ENTER key to remove this message and adjust the contact
of the P probes to ensure good contact is achieved. Press the TEST button
again. P circuit continuity will be checked and if satisfactory DLRO600 will
proceed to carry out a test. After a short period of time, if there is inadequate
contact in the C circuit the instrument will display “CURRENT LOOP
FAIL”. Press Enter to remove this message, make good the connection and
press the TEST button to start the test. A sequence of bars will appear across
the display while the test is being completed.
To make another measurement, ensure the test leads are connected and
press the Test button.
NORMAL mode is abbreviated to NORM under the TEST heading in the
main menu screen.
Continuous Mode
Continuous mode requires the current leads and the voltage leads to be
securely connected to the item under test before pressing the Test button.
The DLRO600 checks voltage and current loop continuity as in Normal
Mode and, if adequate, passes a continuous d.c. current, repeating resistance
measurements at approximately 2-second intervals until the test is terminated
by pressing the Test button (or until the DLRO600 overheats if particularly
high currents are used).
CONTINUOUS mode is abbreviated to CONT under the TEST heading in
the main menu screen.
Overheating
When operating continuously at 600 A, overheating will occur after
approximately 3 minutes (assuming a starting temperature of 20
º
C). A
message ‘HOT’ will then appear on the display until the internal parts have
cooled. When the ‘HOT’ message is on the screen, test current is turned off
and all front panel controls are disabled.
Operating at reduced current will considerably extend the operating time.
Automatic Mode
In Automatic mode, only connect the current leads to the sample to be
measured. Press the TEST button. The red status lamp next to the TEST
button will flash signifying that DLRO600 is armed and will remain in a
state of readiness until the P circuit is completed. At this time the light will
illuminate continuously and the test will be carried out. The progress of the
test is shown by a series of bars progressing across the display.
To make another measurement it is necessary to break P probe contact with
the test sample and remake contact.
For example, if measuring joints in a long bus bar, you may leave the current
circuit connected at opposite ends of the bus bar knowing that current will
only flow during a measurement i.e. when the P probes are connected.
Simply making contact with voltage probes across the joint(s) you wish to
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