Buzzer Threshold; Measurement Methods And Sources Of Error; Insulation Resistance; Making An Insulation Measurement - Megger MFT1700 series User Manual

5.6

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 the SETUP section 10 of this guide.
Selectable limits of 0.5 Ω, 1 Ω, 2 Ω, 5 Ω, 10 Ω, 20 Ω, 50 Ω, 100 Ω. (depending on model) are available.
This setting is stored even when the instrument is switched off.
5.7

Measurement methods and sources of error

Method of measurement
The 2-wire lead set must be used for this measurement. A d.c 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.
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Presence of AC voltages on the circuit being measured
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A poor connection to the circuit under test
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Incorrectly nulled test leads
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Use of fused leads
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6.

Insulation resistance

IMPORTANT:
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.
6.1

Making an INSULATION measurement

.1 Set the left hand rotary range knob to the
.2 Connect two test leads to the L1 (+ve ) and L2 (-ve) terminals on the instrument.
12
insulation test voltage required: