Megger BMM2000, BMM2080, BMM2000ESD User Manual

M BMM2000 Series

Insulation Multimeters

User Guide

SAFETY WARNINGS

• Safety Warnings and Precautions must be read and
understood before the instrument is used. They

must be

observed during use.

• The circuit under test must be de-energised and isolated
before connections are made except for voltage measurement.

• Circuit connections must not be touched during a test.

• After insulation tests, capacitive circuits must be allowed to

discharge

before disconnecting the test leads.

• The Live Circuit Warning and Automatic Discharge are additional
safety features and

should not be regarded as a substitute for

normal safe working practice.

• Replacement fuses must be of the correct type and rating.
Failure to fit the correctly rated fuse

will result in damage to the

instrument in the event of an overload.

• Test leads, including crocodile clips, must be in good order,
clean and have no broken or cracked insulation.

• Ensure that hands remain behind guards of probes/clips when
testing.

• U.K. Safety Authorities recommend the use of fused test leads
when measuring voltage on high energy systems.

NOTE

THE INSTRUMENTS MUST ONLY BE USED BY

SUITABLY TRAINED AND COMPETENT PERSONS

Users of this equipment and/or their employers are reminded that
Health and Safety Legislation require them to carry out valid risk
assessments of all electrical work so as to identify potential
sources of electrical danger and risk of electrical injury such as
from inadvertent short circuits. Where the assessments show that
the risk is significant then the use of fused test leads constructed
in accordance with the HSE guidance note GS38 ‘Electrical Test
Equipment for use by Electricians’ should be used.

Symbols used on the instruments are:

Caution, risk of electric shock.
Caution, refer to User Guide.
Equipment protected throughout by

Double Insulation (Class II).
Equipment complies with current EU Directives.
Equipment must not be connected

to installations >500V.

>500V

GENERAL DESCRIPTION

The Megger BMM2000 Series instruments are battery
powered Insulation and Continuity testers, with a measurement
capability from 0,01Ω Continuity to 200GΩ Insulation.

Offering multi-voltage facilities, the instruments take full
advantage of microprocessor technology and feature a large
liquid crystal display combining digital and analogue readings.
The analogue display has the benefit of indicating trends and
fluctuations in readings, while the digital readout gives direct
accurate results. The display is also backlit giving clear visibility
even in low light conditions.

The BMM2000 Series instruments have the unique capability of
being able to measure voltages down to a resolution of 0,1mV.
This gives the user the option to fit a wide variety of
transducers to further enhance the capabilities of the BMM
Series instruments, eg temperature or humidity measurement.

A customised connector on the top of the instrument enables
the optional Megger SP1 Switched Probe to be used for two
handed probe operation.

The 250V, 500V and 1000V ranges can be used to test
electrical installations in compliance with BS7671 (16th Edition
IEE Wiring Regulations) IEC364 and HD384, since each range
has a 1mA minimum test current at the minimum pass values
of insulation specified in these documents. The 100V range is
ideal for testing telecommunications equipment which would be
damaged by higher voltages. The 50V range is useful for
testing sensitive equipment, such as electronic components,
and computer peripherals.

The BMM2000 series instruments have a current facility which
enables up to 500mA to be measured, (not ESD models), this
together with Ω, V and mV ranges means that the instrument can
realistically be used in situations where previously a multimeter
would be needed.For higher currents an optional current clamp is
available.

Designed to IEC1010-1 the BMM2000 Series are protected
against connection to a 500V Category III supply. The
instruments have a basic accuracy of ±2% at 20°C. The
instruments are waterproof and dustproof to IP54. This helps
maintain accuracy and ensures maximum reliability in harsh
environments.

OPERATION

Refer to Safety Warnings before using the instrument

Testing is automatically inhibited if:

• An external voltage >25V is present when switched to any
insulation range position.

• An external voltage >10V is present on all other ranges
(excluding OFF/V).

The external voltage is indicated on the display, on insulation
ranges an audible bleeper will sound if a test is attempted.

Live Circuit Warning

When more than 25V (10V on 10V insulation range) is applied
to the terminals in the insulation ranges, the instrument defaults
to a voltmeter and gives an audible warning if a test is
attempted.On all other switch positions except OFF/V when
approx 10V is applied the default voltmeter will be activated.
Testing will be inhibited.

Voltage Testing on High Energy Systems

Use extreme care when using or measuring voltages above
30V, particularly in high energy systems. Fused test leads are
available as optional accessories for local situations where
increased protection is required.

Auto-shut Off

To conserve battery life, Auto-shut Off (preceded by a series of
bleeps) operates after approx. 10 minutes of instrument
inactivity on insulation, 5 minutes on all other ranges. If the
instrument is switched on whilst holding the key, the
Auto shut-off time is extended to 60 minutes. To restore
operation after Auto-shut Off, either select OFF followed by the
required switch position.

Note: It is recommended that the instrument is switched to the

OFF position when not in use.

Backlight

The backlight is activated by pressing the key. The
backlight will remain illuminated for approx. one minute before
automatically switching off to conserve battery life, alternatively
the key can be re-pressed.

Insulation Tests (MΩ) (See fig. 1)
The insulation tests apply a known voltage to the circuit under
test and measure the resulting leakage current. The circuit
under test must be completely de-energised and isolated
before test connections are made.

Insulation tests are only initiated when the TEST button is
pressed.

1. Set the range switch to the test voltage required.

2. Connect the test leads, first to the instrument, and then to
the isolated item under test.

3. Press the TEST button to activate the test voltage. Take
the reading.

4. Release the TEST button at the end of the test.

5. Any capacitive circuits charged during a test will automatically
discharge. If significant voltage remains the voltage warning
will occur and the voltage present displayed.

6. Remove the test leads only when no voltage is indicated.

Locking Test Button (ltb)

When it is desired to do a long insulation test, the test can be
‘locked on’ by pressing the key while the test button is
held down. The warning will appear on the display and
both buttons may be released whilst the test continues. The
next press of the test button will terminate the test.

~

~

Note: There is a short delay

on the first operation of
‘1000V’ range, each
time the range is
selected. This is to
prevent accidental
application of 1kV.

The MΩ range features a
leakage current display.
Leakage current is the value
of current that flows during
the insulation test. To view
the leakage current press the

key. To view insulation resistance press the key

again.

Good Procedure Whilst Insulation Testing

Care must be taken when taking measurements greater than a
few GΩ. The leads must be clean dry and in good condition.
They must also not be allowed to tangle. It is also advisable
that the switched probe SP1 is not used as the accuracy at
high value measurements is not guaranteed. The instrument
should also be clean and dry with particular attention paid to
the terminals. Also attempt to reduce any leakage that may
give erroneous results on the item under test.

Polarisation Index Testing

Polarisation Index (PI) is the term applied to the Dielectric
Absorption Ratio when resistance values are measured after
1 minute and again after 10 minutes. Polarization Index is then
the resistance value after 10 minutes divided by the resistance
value after 1 minute. The test can be run at any voltage. More
detailed information on PI Testing and value assessment can
be found in Megger Limited publications listed in the
Accessories page.

Automatic Discharge

When the TEST button is released after an insulation test (or
re-pressed if

ltb

feature is enabled), a 200kΩ load is
automatically switched across the terminals to discharge the
item under test. Any voltage present will be indicated on the
display so that the discharge can be monitored.

TYPICAL TERMINAL VOLTAGE CHARACTERISTICS

FIG.1

50V - 1000V Ranges

10V Range

Continuity Testing (Ω) (See fig.2)
The continuity tests are activated

when the probes make contact of less
than a few kΩ. The tests apply a
constant current and measure the
resulting volt drop across the circuit
under test. The test operates without
the need to press the TEST button.
When the test leads are removed the
reading will hold for a few seconds
and then reset. To recall the last result
press the key. This range is not
suitable for diode testing since the
automatic contact detector will not be
activated when connected to a diode.

1. Set the selector switch to Ω.

2. Connect the test leads.

3. The test will activate automatically.

4. After the test probes are disconnected, the reading will be

held for a few seconds.

Zeroing of Test Lead Resistance

The resistance of the test leads can be nulled on the continuity
range (up to 9,99Ω). The null information is retained in non­volatile memory and so will be remembered when the
instrument is switched off.

1. Select the Continuity range.

2. Short the test leads across a known good conductor using

prods.

3. When the reading has stabilised, press the TEST button.

The zero offset symbol will appear.

4. To release the zero offset press the TEST button again.
The continuity range features a range lock facility. To LOCK the

continuity range press the key, the LOCK symbol will
appear. To scroll through the available ranges press the

key. To de-select the LOCK feature hold the key

down.

Possible sources of error

Measurements and results can be effected by the following:

• The impedance of operating circuits connected in parallel

• Impedance such as inductors that vary during the measurement

• A poor connection to the circuit under test.

Continuity Bleeper

The continuity bleeper sounds continuously when less than 5Ω
is detected. Short bleeps will sound for resistances lower than
a few kΩ and above 5Ω.

1. Set the selector switch to

2. Connect the test leads.

FIG.2