18
NULL
ON
Ω
NULL
ON
Ω
4 Operate the Continuity Null (F1) button, this will null out the lead resistance and the
indicated reading should go to zero.
5 Release the test button. Press the test button and ensure the display reads zero before
proceeding. While using the Continuity null function, “NULL ” is displayed on the LCD as
indicated in Fig.13. The null value will be stored even if the instrument is powered off. This
memorized null value can be cancelled by disconnecting the test leads and pushing the
Continuity Null button (F1) with the test button pressed or locked. When this is cancelled
you will know because NULL OFF is displayed on the LCD.
CAUTION - before taking any measurements always check the leads have been zeroed.
6 Connect the test leads to the circuit whose resistance is required (see Fig.14 for a typical
connection arrangement), having first made sure
that the circuit is not live
. Note that
“Live Circuit” warning will be displayed on the LCD if the circuit is live - but check first
anyway!
7 Press the test button and read the circuit resistance from the display. The reading will have
the test lead resistance already subtracted if the Continuity null function has been used.
8 Note that if the circuit resistance is greater than 20Ω the instrument will autorange to the
200Ω, if it is greater than 200Ω it will autorange to the 2000Ω range.
Note: If the reading is greater than 2000
Ω
the overange symbol ‘>’ will remain
displayed.
WARNING
The results of measurements can be adversely affected by impedances of additional
operating circuits connected in parallel or by transient currents.
Fig.13
