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18
Operation
Switch probe (SP5)
In CONTINUITY/RESISTANCE mode all measurements can be made with the remote switch probe (SP5). Tests are
automatic and do not require the
TEST
button to be pressed.
Connect the switch probe to the switch probe socket L1 (+ve). The switch probe replaces the standard RED test
lead as in ‘Making a continuity measurement’ above.
Buzzer threshold
If the measured resistance is less than the buzzer threshold, the buzzer will sound. The resistance at which the
buzzer stops sounding can be changed to meet individual test requirements. Refer to “Setup options” on
page 26 of this guide.
Selectable limits of 0.5 Ω, 1 Ω, 2 Ω, 5 Ω, 10 Ω, 20 Ω, 50 Ω, 100 Ω, are available.
This setting is stored even when the instrument is switched off.
Measurement methods and sources of error
Method of measurement
The 2-wire lead set must be used for this measurement. A DC voltage of nominally 4.4 V with a current limit of
>200 mA is used to measure resistance less than 2 Ω.
Possible sources of error
Measurement results can be affected by the following:
The presence of circuits connected in parallel.
Presence of AC voltages on the circuit being measured.
A poor connection to the circuit under test.
Incorrectly nulled test leads.
Use of fused leads.
Insulation resistance
500
V
NOTE:
The insulation test is protected by a live circuit warning. Detection of a voltage over 50 V will inhibit
testing. This applies whether or not the insulation test is locked on.
