| Quality is crafted into every Major MEGGER® Insulation
Tester, with excellent test voltage regulation, direct
measurement readout and an external guard terminal to
eliminate surface leakage current from the measurement.
Five models are available for general purpose testing which
include a low-voltage model.
All are portable, self-contained instruments designed to give
rapid and accurate measurements.
Four of the models feature an analog display having four
selectable test voltages of 100, 250, 500 and 1000 Vdc,
measuring insulation resistance up to 2000 M½, and an ohm
range to 5000 Å . The other model has four test voltages of
50, 100, 250 and 500 Vdc measuring insulation resistance up
to 1000 MÅ .
The only other difference between the five analog models is
the type of power source. Power for models MJ159 and
MJ160 is derived from a low-voltage, hand cranked
generator which has been designed to be easy to turn even
under full load conditions. The low-voltage generator is
connected to an electronic inverter to provide a very stable
test voltage. Accuracy of measurement is unaffected by
variations in the generator cranking speed and the test
voltage is maintained at its rated value. Power for model
MJ359 is provided by 120 V ac 50/60 Hz or low-voltage
generator. Model MJ559 is also 120 Vac 50/60 Hz or internal
rechargeable batteries and model MJ459 is powered by 6
replaceable “AA” alkaline cells.
As a safety feature, the ac voltage range becomes effective as
soon as the instrument is connected to the circuit under
test. Therefore, a warning is given that the circuit under test
is not de-energized before the instrument is operated.
Though calibrated for ac voltage, this range also monitors
the automatic discharge feature so that after equipment
having capacitance (i.e. a cable), has been tested, an
indication can be given that the voltage has discharged to a
level that is safe for removing the test leads.
Each instrument has a guard terminal which may be used to
prevent the effects of surface leakage from influencing the
readings. This is achieved by diverting the leakage current
through the guard terminal and away from the instrument’s
measuring circuit.
Each instrument is built into a strong ABS plastic case with a
fold down carrying handle. | 
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