Megger BMM2500 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 6172-484 Edition 3 – Printed in England – 01HH

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 de l’utilisateur
B e d i e n u n g s a n l e i t u n g

I N S U L ATION MULTIMETERS

MEGGER BMM2500

CONTENTS

2

Symbols used on the instrument are:

Risk of Electric Shock

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

Safety Warnings 3

General Description 4

Continuity Testing 9
Continuity Bleeper 10
Millivolt Tests 11
Capacitance Tests 12
Milliamps Tests 12
Storing Results 13
Datalogging 16
Setup Modes 18

Specification 20
Repair and Warranty 25

3

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-energized 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

T H E I N S T R U M E N T S M U S T O N LY B E U S E D B Y S U I TA B LY T R A I N E D A N D C O M P E T E N T P E R S O N S

. U S E R S O F T H I S E Q U I P M E N T

A N D

/O R T H E I R E M P L O Y E R S A R E R E M I N D E D T H AT HE A LT H A N D SA F E T Y LE G I S L AT I O N R E Q U I R E T H E M T O C A R R Y O U T VA L I D

R I S K A S S E S S M E N T S O F A L L E L E C T R I C A L W O R K S O A S T O I D E N T I F Y P O T E N T I A L S O U R C E S O F E L E C T R I C A L D A N G E R A N D R I S K

O F E L E C T R I C A L I N J U RY S U C H A S F R O M I N A D V E RT E N T S H O R T C I R C U I T S . W H E R E T H E A S S E S S M E N T S S H O W T H AT T H E R I S K I S
S I G N I F I C A N T T H E N T H E U S E O F F U S E D T E S T L E A D S C O N S T R U C T E D I N A C C O R D A N C E W I T H T H E HSE G U I D A N C E N O T E G S 3 8

‘ EL E C T R I C A L TE S T EQ U I P M E N T F O R U S E B Y EL E C T R I C I A N S ’ S H O U L D B E U S E D .

GENERAL DESCRIPTION

4

The MEGGER®BMM2500 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 BMM2500 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 M E G G E R®S P 1

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 IEEE 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 (BMM2580) is ideal for testing
telecommunications equipment which would be
damaged by higher voltages. The 50V range
(BMM2580) is useful for testing sensitive equip­ment, such as electronic components, and com­puter peripherals.

The BMM2500 series instruments have a current
facility which enables up to 500mA to be mea­sured, 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.

5

The BMM2500 series instruments have an
RS232 interface built in, and will allow the stor­age and download of results to a PC. The instru­ments come with all the necessary software to
download and tabulate the results. The down­load format is also AVO Powersuite compatible
enabling instruments to form part of an integrat­ed test and certification system. The BMM2500
series instruments also have the capability to
data-log results over an extended time period so
that long term measurements of systems can be
taken.

Designed to IEC1010-1 the BMM2500 Series are
p rotected 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

6

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/mV).

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 if a
test is attempted. On all other switch positions
except O F F / V / m V when more than 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 volt-

ages 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 (pre c e d e d
by a series of bleeps) operates after appro x .
1 0 minutes of instrument inactivity on insulation,
5 minutes on all other ranges. If the instrument is
switched on while holding the k e y, the Auto
s h u t - O f f time is extended to 60 minutes. To
re s t o r e operation after Auto-shut Off, select O F F
followed by the re q u i red 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.

∼

7

Insulation
Tests (MΩ)
(See fig.1)

The insulation tests
apply a known volt­age to the circ u i t
under test and
m e a s u re the re s u l t­ing leakage curre n t .
The circuit under
test must be com­pletely d e - e n e r-
g i s e d and i s o l a t e d
b e f o re test connec­tions are made.

Insulation tests are only initiated when the TEST but-
ton 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.
( P ress the TEST button if the l t b f e a t u re is

enabled). The last reading will hold on the display.

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 XXXXX 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 ‘1000 V’ 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 XXXXX key. To view insulation resis­tance press the XXXXX key again.

FIG.1

∼

8

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

Polarization Index (P I) is the term applied to the

Dielectric Absorption Ratio when resistance values

a r e measured after 1 minute and again after 10 min-

utes. 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.

M o re detailed information on P I 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
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

Continuity Testing (Ω) (See fig.2)

The continuity tests are activated when the probes
make contact of less than a few kΩ. 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 XXXXX 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 non-volatile memory and so will be
re m e m b e red 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
z e ro offset symbol

will appear.

4. To release the zero
offset press the test
button again.

The continuity range
f e a t u res a range lock
f a c i l i t y. 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.

9

FIG.2

10

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 5 Ω 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.

Display: Audible:

<5Ω continuous bleep
<3kΩ short bleep
>3kΩ no bleep

Resistance Tests (kΩ)

This is a low voltage (5 V) low current (25 µA) 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 kΩ range features a range lock facility. To

LOCK the kΩ range press the key, the LOCK
symbol will appear. To scroll through the available
ranges press the key. To de-select the L O C K
f e a t u re hold the key down.

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 30kΩ, and a reverse junc­tion much higher. These features together with the
small test current and wide measurement range

∼

11

(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.

To view the frequency of the a.c. V being measure d
p ress the k e y. The frequency will be displayed
in the range 16Hz-460Hz. To view a.c. V press the

key again.

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 a.c. or d.c. mV using the
key.

3. Connect the test leads.

4. After a short settling time, the reading will be

displayed automatically.

Note: Live circuit warning does not function on mV
range.

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.

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 but-

ton again.
To view the frequency of the a.c. mV being mea­sured press the key. The frequency will be
displayed in the range 16Hz-460Hz. To view a.c.

12

mV press the key again. For inputs less than
10mV frequency is not displayed.

Capacitance Tests (uF)
(BMM2580 only)

The measured capacitance is indicated on the display.

1. Set the selector switch to uF.

2. Connect the test leads to the circuit under test.

3. After a short settling time, the reading will be
displayed automatically.

Zeroing of uF

To zero the uF range, disconnect the leads, wait for

the reading to settle and then press the TEST but-
ton. Up to 10,0nF can be zeroed on the uF range.

The symbol will appear to indicate the zero
has been adjusted.

1. Select the uF range.

2. Disconnect the test leads from the circ u i t
under test.

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 range is suitable for the testing of discrete
components and short low interference level signal
lines. If electrolytic capacitors are being tested
then the red lead should be connected to +ve of
the capacitor. This range is not suitable for check­ing capacitance of signal lines which are subject to
high levels of a.c. interference.
When the test is started – – – will show on the dis­play, if there is excessive noise this symbol will
remain or flash indicating that there is too much
noise for a result to be reached.

Milliamps Tests (mA)

Because of the low source impedance associated
with current measuring this test has an added fea­ture ensuring that when the range is first entered
the default voltmeter is visible. Testing will be inhib­ited if more than 25V is present at the terminals. To
start testing the TEST button should be pressed
and held down for approx. 2 seconds to activate
the mA range. Once activated, the TEST button
no longer needs to be used and the measured
value will be displayed automatically. To switch the
display between a.c. and d.c. press the

∼

13

key.

1. Set the selector switch to mA.

2. Connect the test leads.

3. Select either a.c. or d.c. m A using the

k e y.

4. Press and hold down the TEST button for

approx. 2 seconds.

5. After a short settle time, the reading will be
displayed automatically.

To view the frequency of the a.c. mA being mea-

sured press the key. The frequency will be
displayed in the range 16Hz-460Hz. To view a.c.
mA press the key again. For inputs less than
10mA frequency is not displayed.

Storing Results on MΩ and Ω (RCL)

After an insulation test or continuity test the result
is displayed on the screen, this may be saved with
additional information. A circuit number (1-99) may
be assigned and circuits may be grouped using the
distribution board feature. In this way, when down­loading to AVO PowerSuite, the results can be eas­ily split into different test schedules. When the
results are displayed or printed, a change in the
distribution board is indicated.

Changing Distribution Boards (DB)

Before a test the distribution board number may be
changed as follows:-

1. Move the rotary selector switch to the RCL
position. The code rcl is displayed.

2. Press the key. The currently selected DB

code is displayed, e.g. d01.

3 . This number may be changed using the

and keys to display the re q u i red number.

4. The number can be accepted by pressing the

key, or aborted by pressing the EXIT button.

5. When the number is saved the code Std is

displayed (accompanied by a long bleep) to
confirm that the data has been saved.

∼

∼

14

Testing may now continue with all subsequent

results associated with the new distribution board

number.

Storing a result

On completion and display of the measurement:-

1. Press and hold the key. After about 1
second, a bleep will be heard. For both
Continuity and Insulation, a code, as given in
the following table is displayed. This code is
used to describe the circuit tested and can
accordingly be modified by the user.

2. The code may be changed by pressing the

and keys.

3. The code may be accepted by pressing the
key, or aborted by pressing the EXIT button.

4. The circuit number is then displayed as
2 digits e.g. c01.

Note:- Many different tests may be saved under

the same circuit number.

5. The circuit number may be changed by
pressing the and keys to display
an appropriate number.

6. The number can be accepted and the
results saved by pressing the key, or the

procedure aborted by pressing the EXIT but­ton.

7. When the result is saved, the code Std is

displayed (accompanied by a long bleep) to
confirm that the data has been saved. The
display of FULL indicates that there is no more
test storage. Approx. 300 results can be stored
in memory.

Test to be Saved Display code Meaning

Continuity r1 Single CCT

r2 Single CCT
rr1 Ring CCT
rr2 Ring CCT
rrn Ring CCT
r12 R1+R2 ReturnCCT

Insulation n_e N-PE

L_n L-N
L_E L-PE
L_L L-L

∼

∼

15

Delete all data

1. Move the rotary selector switch to the RCL

position. The code rcl is displayed.

2. Press the and keys together. The

code dEL is displayed.

3. Confirm that the data is no longer required by
pressing the key or abort by pressing any

other key. The code rcl is displayed.

Print Results (see Setup Modes)

1. Connect printer and the instrument with a ser-

ial printer lead.

2. Move the rotary selector switch to the RCL
position. The code rcl is displayed.

3. Commence the printout by pressing the TEST
button. Abort at any time by pressing and hold­ing the k e y . The code rc l is displayed.

Retrieve Stored Results

It is possible to view previously stored test results
by switching the rotary switch to the RCL position.

1. Move the rotary selector switch to the RCL

position. The code rcl is displayed.

2. Select the re q u i red distribution board by

pressing the and keys.

The distribution board numbers are shown in
the order that the results were stored. A long
bleep is sounded when the end of the list is
reached.

3. Press the key to list the circuit numbers
used in the currently displayed distribution
board or press the EXIT button to return to the
RCL display.

4. Select the required circuit number by pressing
the and keys. The circuit numbers
are shown in the order that the results were
stored. A long bleep is sounded when the end
of the list is reached.

5. Press the EXIT button to return to the distribu­tion board selection screen, or press the

XXXXXkey to show the stored test codes. The

following codes are used to identify test
results:-

Code Meaning

Con Continuity Test
InS Insulation Test

6. Select the re q u i red test by pressing the

and keys. The tests are shown in

∼

∼

∼

∼

16

the above order. Hold a key down to auto­repeat. A long bleep is sounded when the end
of the list is reached.

7. Press the EXIT button to return to the circuit

number selection screen, or press the key
to scroll through the stored test results,
together with any additional connection
information.

Download to PC

The BMM series has been designed to be used

with AVO Powersuite for Windows which will
accept the test results and enable the production
of various certificates, including Periodic

Inspection and Completion. The CD supplied with

the instrument contains AVO Download Manager
Program. This enables stored and data-logged

results to be downloaded to a PC, the creation of

simple test report files which may be exported to
other applications and used to create data back­ups or reports/certificates. Download manager
also enables certain changes to be made to your
instrument setup such as changing the 2nd lan-

guage of the printouts. The CD contains a user

guide giving you full instructions on the use of
Download Manager.

Cable Configuration

Normally, a double-ended 9-way ‘D’ female socket
lead suitable for connecting PC to PC is required.
This lead should not exceed 3m in length. A lead is
available as an accessory, or one can be made up
as follows:–

Datalogging

Datalogging means the automatic recording of
measurements at regular intervals over an extend­ed period, for viewing at a later time. Results are
held in the internal memory of the tester, but can
only be extracted by means of a PC connected via
the RS232 port.

Signal Insulation Tester 9-way ‘D’ 25-way ‘D’

Rx 2 3 2
Tx 3 2 3
DSR 6 4 20
GND 5 5 7

17

Storage v. Datalogging Comparison.

By storage, we mean the saving to memory of
results one-by-one as tests are performed. Each
result has to be individually saved after associating
it with user-selectable connection data and circuit
number, along with a previously chosen distribu­tion board number. However, when data logging is
running, results are automatically and continuous­ly saved to memory and no other information is
recorded.

Storage and logging are mutually exclusive func­tions. The instrument cannot be set up to perform
both operations at any given time. If a result is
stored, then all logged data is erased, and vice
versa. Also, only one set of logged data can be
held in memory. A new logging session will erase
the previous data. This differs in behaviour from the
storage function, in which data from successive
tests accumulates in the memory until it is full.
Another difference between storage and logging is
that the former applies only to insulation and con­tinuity testing, whereas all types of measurement
can be logged (buzzer range excluded).

Starting a logging session

Once logging has been enabled and the interval
set up, a session of data-logging can begin. (see
Setup Modes)

1. Hold down the key and turn the rotary
switch to the desired function.

2. Release the key. The message log will
be seen. To confirm that logging is required,
p ress the display key and a confirming

message will be shown briefly.

3. Pressing EXIT will cancel logging and off will
be displayed.

If data-logging is turned on, it will commence as
soon as the test starts. That is, immediately on
volts, millivolts, ohms, kΩ and capacitance func­tions, or when the test button is pressed on insula­tion and milliamps ranges. On milliamps or milli­volts functions, press theXXXXXkey if required,
after logging has started.

Stopping a logging session

While a logging session is running, it can be
stopped at any time by turning the range switch.
Any data logged up to that point will be retained.

∼

18

Alternatively, logging can be left running and will
stop automatically a short while after the memory
becomes full.

The number of results which can be logged is
about 300, after which the message ‘full’ will be
flashed on the display for a few minutes. The
instrument will then shut down.

Other considerations

Note that the batteries may not last through the
whole logging session, depending on their condi­tion and on the log interval which has been set. If
the batteries should fail, any results already logged
will be retained. Note also, that if the TEST button
has been set for non-latching operation, this will be
temporarily overridden during logging of insulation
results, giving a press-to-start, pre s s - t o - s t o p
action. The TEST button’s mode of operation will
return to its original setting after the logging ses­sion has finished.

Viewing logged data.

Logged results can only be retrieved via the instru­ment’s RS232 port, using a PC connected via a

serial cable. The disk supplied with the instrument
carries a programme capable of handling the data.

The method is similar to that for ‘downloading’
stored results. For further information see the sec­tion entitled “Download to PC”. Note that on milli­volts d.c. and milliamps d.c. measurements, the
frequency result is always set to zero. On millivolts
a.c. and milliamps a.c. measurements, the fre­quency result is set to zero if the frequency could

not be measured.

Setup Modes

Serial Printer configuration

The printer should be set to 9600 baud, 8 bit data,
no parity and 1 stop bit. This instrument uses a
special isolated serial interface which is powered
from the PC or printer. In the unlikely event that
your PC or printer is not able to power the inter­face, it will be necessary to provide an additional
supply. Contact AVO Product Support for details.

Printer Setup Mode

The instrument cannot respond to a busy signal

∼

19

given by a printer, and therefore waits at the end of

each line. This time (“Printer delay time”) and the

printer report language can be changed.

1. Press and hold the key then turn the

rotary selector switch from the OFF position to
the RCL position. The code Pdt is displayed.

2. Release the key.

To change the Printer speed

1. Toggle the key to scroll through and

display the code Pdt

2. Press the key. The current setting is
displayed.

3. Toggle the and keys until the
required setting is displayed.

4. To save the new setting, press the key.

The bleeper sounds and std is displayed. To

abort the new setting, press the EXIT button.

To select the printer language

1 . P ress the key to scroll through and dis-

play the code l n g.

2 . P ress the key. The current printer re p o r t

language is displayed as 1 (English) or 2 (as
given on the type label on the User Guide cover).

Note: Language 2 can be changed – see below.

3. Press the key until the required language
setting is displayed

4. To save the new setting, press the key.

The bleeper sounds and is Std displayed. To
abort the new setting, press the EXIT button.

Changing the Second Printer Language

Language 2 can be changed using AVO Download
Manager Program supplied with your instrument. Full
instructions are contained in the User Guide with the CD.

Data-logging

Enabling/disabling data-logging:
The factory setting is that logging is disabled and
storage is enabled.

1. Turn the range knob to ‘RCL’ while holding
down the key. Pdt will be displayed.

2. Press the key until log is showing

3. Press the key to show the current status
of the logging function, i.e on or off.

4. Pressing the key toggles the setting
between on and off.

5. Press the key to accept the setup, or the

EXIT button to quit.

∼

20

Setting the data-logging interval.

1. While log is being displayed, press the

key. Int will appear on the display.

2. Press the key to see the value of the log­ging interval (in seconds)

3. Set the interval in 10 second steps with the
and keys (max. value 1990 sec-

onds, min. value 10 seconds)

4. Press the key to accept the new value,

or the EXIT button to quit.

5. Press the EXIT button again to escape from

the logging setup screens. The display will
s h o w rc l.

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 two­handed 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), IEC 1010-1 (1995), EN61010-1 (1995)
Category III* 300 V phase to earth and 500V phase
to phase. The probe is fitted with an internal, non­replaceable fuse, to protect the user should the
probe be used accidentally in conjunction with a
testlead 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.

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 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

21

fitted with the correct polarity in accordance with
the label in the battery holder. Reconnect the bat­tery holder to the battery leads. Replace and re­secure the battery compartment cover. Remove
the cells if the instrument is not going to be used
for an extended period of time.

Fuse Checking and Replacement

To check the instrument fuse, switch to an insula­tion range and press the TEST button. The symbol

XXXX 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.

Specification

22

(All quoted accuracies are at +20ºC.)

INSULATION RANGES

Nominal Test 250V,500V,1000V (BMM2500)

Voltage (d.c.): 50V,100V,250V,500V,1000V (BMM2580)

Test voltage accuracy: +15% maximum on open circ u i t
Short circuit curre n t : < 2 mA

Test Current on load: 1mA at min. pass value of insulation

specified in BS7671, HD384 and
IEC 364, 2mA max.

Accuracy:

(BMM2500)

Range Full Scale Accuracy

1000V 20GΩ ± 2% ± 2 digits ± 0,2% per GΩ
500V 10GΩ ± 2% ± 2 digits ± 0,4% per GΩ

250V 5GΩ ± 2% ± 2 digits ± 0,8% per GΩ

(BMM2580)

Range Full Scale Accuracy

1000V 200GΩ ± 2% ± 2 digits ± 0,2% per GΩ
500V 100GΩ ± 2% ± 2 digits ± 0,4% per GΩ

250V 50GΩ ± 2% ± 2 digits ± 0,8% per GΩ

100V 20GΩ ± 2% ± 2 digits ± 2,0% per GΩ
50V 10GΩ ± 2% ± 2 digits ± 4,0% per GΩ

Note: Above specifications only apply when high quality

silicone leads are being used.

Measuring Range:

0,01MΩ to 200GΩ (0-100GΩ on analogue scale).
EN61557 Operating range: 0,10MΩ to 1,00GΩ

Leakage Current: 10% ±3digits

CONTINUITY

Measuring Range: 0,01Ω to 99,9Ω (0 to 10Ω on

analogue scale)

EN61557 Operating range: 0,10Ω to 99,9Ω
Accuracy: ±2% ±2 digits
Open circuit voltage: 5V ±1V
Test current: 210mA ±10mA (0-2Ω)
Zero offset at probes: 0,10Ω typical

Lead resistance zeroing: Up to 9,99Ω
Noise rejection: 1V rms 50/60Hz
Buzzer: Operates at less than 5Ω

(approx).

RESISTANCE

Measuring Range: 0,01kΩ to 9,99MΩ (0 to

100MΩ on analogue scale)

Accuracy: ±3% ±2 digits
Open circuit voltage: 5V ±1V
Short circuit current: 25µA ±5 µA

23

VOLTAGE

Measuring Range: ±1V to ±500V (0 to 1000V

on analogue scale)

Accuracy: 0-500V d.c. ±2% ±3 digit

0-500V a.c (50/60Hz) ±2% ±3 digits
0-500V 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. (16-460Hz) ±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

CAPACITANCE

Measuring Range: 0,1nF to 9,99uF
Accuracy: ±3% ±2 digits ±0,2nF
uF zeroing: Up to 10nF

MILLI-AMPS

Measuring Range: 0,1mA to 500mA (0 to 1000mA on

analogue scale)

Accuracy:

0,1mA to 10mA d.c. or a.c. (50/60 Hz) ±2% ±5 digits
10mA to 500mA d.c. or a.c. (50/60 Hz) ±2% ±3 digits
0,1mA to 10mA a.c. (16-460 Hz) ±5% ±7 digits
10mA to 500mA a.c. (16-460 Hz) ±5% ±5 digits

FREQUENCY

Measuring range: 16Hz to 460Hz
Accuracy: ±1% ±1digit

24

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 volt-

age, 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 0,10Ω measured with the continuity range may give
a display in the range 0,07Ω to 0,13Ω which is a maximum
error of 30%. Therefore the measurement range measur­ing low resistance is 0,10Ω to 99,9Ω. When checking that

a measurement does not exceed a limit, the service error
needs to be taken into account and these tables enable
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. Indicated Reading Limit Min. Indicated 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 10,00 10,8
0,60 0,66 20,00 21,2
0,70 0,77 30,00 31,6
0,80 0,87 40,00 42,0
0,90 0,98 50,00 52,4
1,00 1,08 100,00 94,0

Continuity Resistance – Ω

Limit Max. Indicated Reading Limit Max. Indicated 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