Megger MJ159 Specifications

Major Megger

Insulation Resistance Testers

o scale multipliers

n N

n Multiple test voltages for spot and step

voltage testing

n Guard terminal to eliminate surface

leakage current

MJ TESTERS

nsulation Resistance Testers

I

DESCRIPTION

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 por
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 M
range to 5000 ≈ . The other model has four test voltages of
50, 100, 250 and 500 Vdc measuring insulation resistance up
to 1000 M

The only other difference between the five analog models is
the type of power source. P
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 V
rechargeable batteries and model MJ459 is powered by 6
replaceable “AA” alkaline cells.

table, self

.

≈

-contained instruments designed to give

Ω, and an ohm

ower for models MJ159 and

ac 50/60 Hz or inter

nal

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.

APPLICATIONS

The Major Meggers have been designed for convenience
and ease-of-use when testing complex or larger electrical
installations, and commissioning, ser
electrical equipment. They are designed for the safe testing
of motors, generators. cables, switchgear
distribution networks, industrial and domestic installations,
components and appliances.

The range of insulation test voltages available allows one

ument to be used for a variety of applications. For

instr
example, installations and equipment can be tested at

vicing or maintaining

, transformers,

1000 V d.c. when this requirement is specified, also aircraft
and tele-communications equipment can be tested at the
relatively low 100 V d.c. and 110 V to 120 V a.c. systems can
be tested using 250 V d.c.

Test leads with fused prods are available and it is
recommended that these be used when checking that
equipment has been isolated from the supply (by
performing a voltage test), especially in high energy
situations.

MJ TESTERS

Insulation Resistance Testers

SPECIFICATION

Insulation Range

Insulation Resistance: 0.1 Ω - 2000 MΩ (0.1 Ω -1000 MΩ for
MJ160)

Accuracy: ±1.25% of fsd on a 2.8 in. (71.1mm) arc length

Nominal Test Voltages

d.c: 100 V, 250 V, 500 V, 1000 V.

(MJ160 is 50 V, 100 V, 250 V, 500 V)

Accuracy

250 V, 500 V, 1000 V +30%, -0% max.

50 V, 100 V, +40%, -0% max.

Midscale: 4 MΩ (2 MΩ for MJ160)

Short Circuit Current: 1.9 mA

(0.65 mA for MJ160)

Maximum Load Capacitance: 1µF with less than ±0.1" pointer
movement

Discharge: Up to 1 µF capacitance is discharged from 1000 V to
less than 42.4 V in less than 4 secs

Resistance Range

0.1 Ω - 5000 Ω

Test Voltage characteristics

100

80

100V

250V

60

40

TEST VOLTAGE % (OF RANGE)

20

500V

1kV

0

.01.02 .05 .1 .2 .5 1 2 5 10 20 50 100 200 300 1k 2k ∞

TEST RESISTANCE MΩ

Open circuit Test voltage: 3 V ±0.2 V

Short Circuit Current: 2 mA ±10%

Accuracy: ±1.25% of fsd on a 2.8 in. (71.1mm) arc length:

Safety Voltage Check

Voltage measurement: 0.1 V - 600 V a.c; the meter is RMS
calibrated and average responding

Safety voltage indicator: Indicates the presence of d.c. voltages.
Scaling is not the same as the a.c. meter. True d.c. voltage equals
scale reading divided by 2.22

Accuracy: 2.5% of full scale

Power Supplies

MJ159 and MJ160: Low voltage brushless a.c. generator. Cranking
speed between 130 rpm and 170 rpm

MJ359: Dual operation low voltage brushless a.c. generator or 120
V 50/60 Hz mains (line) supply

MJ459: Six IEC LR6 cells (AA) Battery life: not less than 1300
insulation or Resistance range tests

MJ559: Dual operation 120 V 50/60 Hz mains (line) supply and
rechargeable battery. Six Ni Cad cells (e.g. AA, NEDA 15 NC)

Safety

The instruments meet the requirements for double insulation to
IEC 1010-1(1995), EN 61010 (1995) to installation Category II, 300 V
phase to earth (ground), 600 V installation Category I

Flash Test

6 kV a.c. r.m.s.