Megger BMM500 Series User manual

This instrument is manufactured in the United Kingdom.
The company reserves the right to change the specification or design without prior notice.
MEGGER is the registered Trade Mark of AVO INTERNATIONAL LIMITED. Copyright ©, AVO INTERNATIONAL LIMITED
Part No 6172-697 - Edition 1 - Printed in England - 06FF
AVO INTERNATIONAL
Archcliffe Road PO Box 9007 4271 Bronze Way MEGGER SARL
Dover Valley Forge Dallas 29 Allée de Villemomble
Kent, CT17 9EN. PA 19484-9007 TX 75237-1017 93340 Le Raincy
England. U.S.A. U.S.A. Paris, France
Tel: [phone] Tel: [phone] Tel: [phone] (U.S.A. only) Tel: [phone]
Fax: [phone] Fax: [phone] Tel: [phone] (International) Fax: [phone]

MEGGER®
User Guide
Guide d’Utilisateur
Benutzeranleitung
Guía del Usuario
INSULATION & CONTINUITY
TESTERS
MEGGER®BMM500 SERIES

Contents
Safety Warnings 2
Description 3
Operation 4
Live Circuit warning 4
Voltage testing 4
Auto-shut off 4
Backlight 4
Insulation tests 5
Locking Test Button (ltb) 5
Polarisation Index Testing 5
Automatic Discharge 6
Zeroing of Test Lead Resistance 7
Possible sources of error 7
Continuity Bleeper 8
Resistance Tests (kΩ)8
Diode Testing 8
Voltage Tests (V) 9
Battery Replacement 10
Fuse Checking and Replacement 10
Using the MEGGER SP1
Switched Probe 11
Specification 12
Repair and Warranty 19
1
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 voltage sources
>600V CAT II. Suitable for
electrical installations CAT III
300V to Earth
>600V

2
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.

Description
Congratulations on your purchase of a genuine
Megger insulation/continuity tester. Megger has
over 100 years experience in insulation testing
which is reflected in its product designs. Your
BMM500 has been carefully developed to
address the real needs and benefits of the user.
The MEGGER BMM500 Series instruments
are battery powered Insulation and Continuity
testers, with a measurement capability from
0,01ΩContinuity to 10GΩInsulation.
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 BMM500 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. Designed to
IEC1010-1 the BMM500 Series are protected
against connection to a 300V 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.
3

Operation
Refer to Safety Warnings before using
the instrument
Testing is automatically inhibited if:
•An external voltage >55V 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 is applied to the terminals
in the insulation ranges, the instrument defaults
to a voltmeter and gives an audible warning.
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, 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,
4
∼

Operation
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.
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
5
∼

Operation
on PI Testing and value assessment can be
found in AVO International 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 200kΩload 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
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
6
L1
L2
L3
N
Fig.1
1100
1000
900
800
700
600
500
400
300
200
100
0.01 0.1 1 10 100 1000
1000V
500V
250V
RESISTANCE (MΩ)
VOLT (d.c.)

Operation
the reading will hold for a few seconds and then
reset. 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 non-volatile 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.
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.
7
L1
L2
L3
N
PE
Fig.2

Continuity Bleeper
The continuity bleeper sounds continuously
when a resistance below the threshold level is
detected. This can be selected from several
values between 2Ωand 3kΩ. To change the
level press the button. Short bleeps will
sound for values above the threshold but below
approx. 3kΩ
1. Set the selector switch to
2. Connect the test leads.
Display (5Ωlevel selected): Audible:
<5Ωcontinuous bleep
<3kΩshort bleep
>3kΩno bleep
To turn off the audible tone and replace it with a
visual indication of continuity, press the TEST
button whilst switched to the range.
will be displayed momentarily and will
appear when resistances below the threshold
are measured.
Resistance Tests (kΩ)
This is a low voltage (5V) low current (25µA)
test for sensitive electronic equipment. It
operates in the same way as the continuity
ranges.
1. Set the selector switch to kΩ.
2. Connect the test leads.
3. The test will activate automatically.
The resistance range is protected by a high
impedance method and therefore if the
instrument is connected to a live circuit the fuse
will not blow as on the insulation, continuity and
buzzer ranges. The instrument will merely
indicate the applied over-voltage.
Diode Testing
This range can also be used for diode testing,
the positive terminal being the source of the
test current. A forward biased semi-conductor
junction will typically measure 15 to 30kΩand
the diode symbol is shown on the display.
A reverse junction will measure much higher.
These features together with the small test
Operation
8
∼

Operation
9
∼
current and wide measurement range(0,01kΩ
to 10000kΩ) make the resistance range very
useful for general purpose testing.
Voltage Tests (V)
If >1V a.c. or d.c. is present at the terminals the
measured voltage is indicated on the display.
The voltage display will function within
specification even if the fuse has blown.
If the voltmeter operation is in question, test the
voltmeter on a known source.
1. Set the selector switch to V.
2. Connect the test leads.
3. After a short settling time, the reading will
be displayed automatically.
Millivolt Tests (mV)
The measured a.c. or d.c. voltage is indicated
on the display.
1. Set the selector switch to mV.
2. Select either ac or dc mV using the
key.
3. Connect the test leads.
4. After a short settle time, the reading will
be displayed automatically.
Measuring Other Parameters
The BMM500 Series can be used to measure
numerous quantities from temperature to
current to windspeed through the use of mV
output probes. Any compatible probe with a
known output ratio can be used. eg: a
temperature probe with output ratio of 1mV/ºC
will cause the display to indicate directly
in ºC Certain probes require zeroing, eg
windspeed anemometer. The mV zero option
described below provides this facility
Zeroing of d.c. mV (no a.c. mV zero facility)
To zero the d.c. mV range, short the leads
together in the d.c. mV position, wait for the
reading to settle and then press the TEST
button. Up to 9,9mV can be zeroed on the d.c.
mV range. The symbol will appear to
indicate the zero has been adjusted.

Operation
1. Select the d.c. mV range.
2. Short the test leads together.
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.
Battery Replacement
When the low battery symbol appears, the
cells are nearly exhausted and should be
replaced as soon as possible. Use Alkaline
cells IEC LR6 (AA) or NiCd/NiMH
rechargeable. To install or replace the cells,
disconnect the test leads, switch the instrument
to OFF and loosen the captive screws on the
rear of the battery compartment. Remove the
cover and disconnect the battery holder from
the battery leads. Ensure that the replacement
cells are fitted with the correct polarity in
accordance with the label in the battery holder.
Reconnect the battery holder to the battery
leads. Replace and re-secure the battery
compartment cover. Remove the cells if the
instrument is not going to be used for an
extended period of time.
The BMM500 Series incorporates an electronic
contact detector to minimise the chance of
blowing the fuse even if accidentally applied to
a live circuit whilst switched to the continuity
range. In the unlikely event of the fuse needing
replacement, a spare is located under the
battery cover.
Fuse Checking and Replacement
To check the instrument fuse, switch to an
insulation range and press the TEST button.
The symbol will appear if the fuse is
ruptured. To replace the fuse, disconnect the
test leads, switch the instrument OFF and
loosen the captive screws holding the battery
compartment cover in place. Remove the cover
and replace the fuse. Replace and re-secure
the battery compartment cover.
10

Operation
Using the MEGGER SP1 Switched Probe
Operation: The Megger SP1 is an accessory for
designated Megger installation test instruments.
When fitted in the specially designed connector,
in place of the existing ‘Low’lead, the SP1 acts
as a remote test button to operate the instrument
and as a ‘Low’probe. This simplifies instrument
control and two-handed probing. The SP1 is
suitable for use with MEGGER insulation test
instruments up to 1kV output test voltage.
Safety: Meets the safety requirements for double
insulation to IEC1010-2-031 (1995), EN61010-2-
031 (1995), IEC1010-1 (1995), EN61010-1
(1995) Category III*, 300V phase to earth. The
probe is fitted with an internal, non-replaceable
fuse, to protect the user should the probe be
used accidentally in conjunction with a test lead
in the low terminal.
* Relates to transient overvoltage likely to be
found in fixed installation wiring.
Do not use the probe if any part of it is
damaged.
11

Specification
(All quoted accuracies are at +20°C.)
Insulation Ranges
Nominal Test Voltage (d.c.): 250V, 500V, 1000V
Test voltage accuracy: +15% maximum on open circuit
Short circuit current: < 2 mA
Test Current on load: 1mA at min. pass value of insulation specified in BS7671, HD384
and IEC364, 2mA max.
Accuracy Range Full Scale Accuracy
1000V 10GΩ±2% ±2digits ±0,2% per GΩ
500V 5GΩ±2% ±2 digits ±0,4% per GΩ
250V 2GΩ±2% ±2 digits ±0,8% per GΩ
Note: Above specifications only apply when high quality silicone leads are being used.
Measuring Range: 0,01MΩto 10GΩ
(0-100GΩon analogue scale).
EN61557 Operating range: 0,10MΩto 1GΩ
12

Specification
Continuity
Measuring Range: 0,01Ωto 99,9Ω
(0-10Ωon analogue scale)
EN61557 Operating range: 0,10Ωto 99,9Ω
Accuracy: ±2% ±2 digits
Open circuit voltage: 5V ±1V
Test current: 210mA ±10mA (0-2Ω)
Zero offset at probe tips: 0,10Ωtypical
Lead resistance zeroing: Up to 9,99Ω
Noise rejection: 1V rms 50/60Hz
Buzzer: Selectable: operates at less than 2Ω, 5Ω, 20Ω, 50Ω, 200Ω, 500Ω,
3kΩapprox.
Resistance
Measuring Range: 0,01kΩto 9,99MΩ
(0 to 100MΩon analogue scale)
Accuracy: ±3% ± 2digits
Open circuit voltage: 5V ±1V
Short circuit current: 25µA ±5µA
13

Specification
Voltage
Measuring Range: ±1V to ±600V
(0 to 1000V on analogue scale)
Accuracy: 0-600V d.c. ±2% ±3 digit
0-600V a.c (50/60Hz) ±2% ±3 digits
0-600V 400Hz a.c. ±5% ±3 digits
Input resistance: approx 200kΩ.
Detector Threshold: 1V
Millivolts
Measuring Range: ±0,1mV to ±1999mV
(0 to 1000mV on analogue scale)
Accuracy:
0,1mV to 10mV d.c. or a.c. (50/60Hz) ±2% ±5 digits
10mV to 1999mV d.c. or a.c. (50/60Hz) ±2% ±3 digits
0,1mV to 10mV a.c. (16-460 Hz) ±5% ±7 digits
10mV to 1999mV a.c. (16-460 Hz) ±5% ±5 digits
d.c. milliVolts zeroing: Up to 9,9mV
Input resistance: >3MΩ
14

Specification
Basic and service errors for Insulation and
Resistance ranges
The basic error is the maximum inaccuracy of
the instrument under ideal conditions, whereas
the service error is the maximum inaccuracy
taking into effect of battery voltage, temperature,
interference, and system voltage and frequency,
where applicable. After determining the service
error, we can then calculate the measurement
range. This is the range of measurement over
which the error in service is less than 30% of the
reading. Digital instruments are affected by the
number of digits error –for example a value
0,10Ωmeasured with the continuity range may
give a display in the range 0,07Ωto 0,13Ωwhich
is a maximum error of 30%. Therefore the
measurement range measuring low resistance is
0,10Ωto 99,9Ω. When checking that a
measurement does not exceed a limit, the
service error needs to be taken into account and
these tables enables this to be done quickly and
easily. These will guarantee that the value being
measured is greater than or less than the limit
value specified as appropriate.
Insulation Resistance –MΩ
Limit Min. Limit Min.
Indicated Indicated
Reading Reading
0,10 0,14 2,00 2,12
0,20 0,25 3,00 3,16
0,30 0,35 4,00 4,20
0,40 0,46 5,00 5,24
0,50 0,56
0,60 0,66
0,70 0,77
0,80 0,87
0,90 0,98
1,00 1,08
15

Specification
Continuity Resistance –Ω
Limit Min. Limit Min.
Indicated Indicated
Reading Reading
0,10 0,06 2,00 1,88
0,20 0,15 3,00 2,84
0,30 0,25 4,00 3,80
0,40 0,34 5,00 4,76
0,50 0,44 10,00 9,56
0,60 0,54 20,00 18,8
0,70 0,63 30,00 28,4
0,80 0,73 40,00 38,0
0,90 0,82 50,00 47,6
1,00 0,92 100,00 92,0
SAFETY
The instruments meet the requirements for
double insulation to IEC 1010-1 (1995), EN
61010-1 (1995) to Category III*, 300V phase to
earth (ground) without the need for separately
fused test leads. If required, fused test leads are
available as an optional accessory.
* Relates to the transient overvoltages likely to
be met in fixed wiring installations.
Complies with the following parts of EN61557,
Electrical safety in low voltage systems up to
1000V a.c. and 1500V d.c. –Equipment for
testing, measuring or monitoring of protective
measures:-
Part 1 –General requirements
Part 2 –Insulation resistance
Part 4 –Resistance of earth
connection and equi-
potential bonding
FUSE
500mA (F) 600V, 32x 6mm Ceramic HBC 10kA
minimum.
E.M.C.
The instruments meet EN 61326-1.
16

Specification
POWER SUPPLY
Battery Type: 6x1,5V Alkaline
cells IEC LR6 type
or 1.2V NiCd or
NiMH
re-chargeable
cells.
Battery Life (typical): 2100 5-sec 1kV
insulation tests
3200 5-sec 500V
insulation tests
4000 5-sec 250V
insulation tests
2700 5-sec
continuity tests
4700 5-sec kΩ
tests
ENVIRONMENTAL CONDITIONS
Operating range: -10 to +50°C
Operating humidity: 90% RH at 40°C
max.
Storage temperature
range: -30 to +70°C
Calibration Temperature: +20ºC
Maximum altitude: 2000 m
Dust and water protection: IP54
Temperature coefficient: <0,1% per °C
WEIGHT: 742g
DIMENSIONS: 110mm x 220mm
x 45mm
CLEANING: Wipe with a clean
cloth dampened
with soapy water
or Isopropyl
Alcohol(IPA)
17