BM11D/21 Front Cover 1/6/00 10:58 am Page 1

5kV Digital Insulation Testers

MEGGER

®

BM11D

MEGGER

®

BM21

MEGGER ®

User Guide

Guide de l’utilisateur

Gebrauchsanleitung

Guía del usuario

BM11D/21 Contents 1/6/00 11:00 am Page 1

Contents

Safety Warnings

General Description

Features and Controls

Operation

Instrument Controls

Features

Testing Procedures

Battery

Guard Terminal

Condition and Warning Indicators

Application Notes

Preventive Maintenance

Insulation Testing Techniques

Short Time or Spot Test

Polarization Index (PI) Test

Stress Conditions

Specification

13

14

15

15

16

17 -19

7 - 8

8

9

9 - 10

3

4

Accessories

Repair and Warranty

5 - 6 Guide Utilisateur

Betriebsanleitung

Guîa del Usuario

10 -11

11 -12

Symbols used on the instrument are:

Caution: Refer to accompanying notes.

20

21

22 - 37

38 - 53

54 - 69

Risk of electric shock.

Equipment protected throughout by Double

Insulation (Class II ).

Equipment complies with EU Directives

2

BM11D/21 Safety Warning 1/6/00 11:04 am Page 1

3

SAFETY WARNINGS

• The circuit under test must be switched off, de-energised and isolated before insulation test connections are made.

• Circuit connections must not be touched during an insulation test.

• After insulation tests, capacitive circuits must be discharged before disconnecting the test leads.

• Turning the instrument off, and manually discharging of circuits on completion of tests is recommended as standard procedure, before touching any connections.

• In certain circumstances, break-down of the circuit under test may cause the instrument to terminate the test in an uncontrolled manner, possibly causing a loss of display while the circuit remains energised. In this event, it is even more important that the ‘ON/OFF’ key is pressed, and the circuit manually discharged

before touching any connections.

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

• Replacement fuses must be of the correct type and rating.

• The instrument should not be used if any part of it is damaged.

• If water is present in the charger recess, the instrument must not be used. It is recommended that the instrument is not used in wet weather conditions.

• See Battery Charging Power Cord on page 4.

NOTE

T

HE INSTRUMENT MUST ONLY BE USED BY SUITABLY TRAINED AND COMPETENT PERSONS

.

BM11D/21 General Description 1/6/00 11:02 am Page 1

General Description

The BM11D and BM21 are compact, battery powered, high voltage d.c. insulation testers with resistance measurement capabilities to around 1 T

Ω

. The BM11D has a digital full scale of 500 G

Ω whilst the BM21 can measure up to 5 T

Ω

. The

BM21 can be set to display leakage current instead of resistance and this mode of operation also allows higher resistances to be measured, possibly up to 500 T

Ω

.

The instruments are microprocessor controlled and feature a large, clear LCD combining digital and analogue readings of insulation resistance.

To recharge the batteries requires an input voltage within the range 95-265 V a.c., 50-60 Hz. The power input and fuses are located in a splashproof recess on the front panel.

Battery Charging Power cord:

If the power cord plug is not suitable for your type of socket outlets (receptacles), do not use an adaptor. You should use a suitable alternative power cord, or if necessary change the plug by cutting the cord and fitting a suitable plug. The colour code of the cord is:

Both instruments have test voltage positions of 500 V, 1000 V,

2500 V and 5000 V. The BM21 has an additional range with a variable output voltage of 25 V to 5000 V in 25 V steps.

An integral timer is started automatically on commencement of the test, and displays elapsed minutes and seconds since the start of the test. The BM21 timer can be used to set the duration of test, and will automatically stop the output voltage when the time has expired.

At the end of a test, capacitive loads are discharged automatically and the decaying voltage is displayed as the value returns to zero. The test leads should not be disconnected until the item has been discharged fully. Similarly, during a test the test leads should not be removed, and the item under test should not be touched. A flashing LED, and flashing high voltage symbols on the LCD remind the user that hazardous voltage is present.

A battery symbol is displayed continuously showing the condition of the battery.

Power is obtained from internal mains rechargeable batteries.

Earth (Ground)

Neutral

Phase (Line)

Yellow/Green

Blue

Brown

If using a fused plug, a 3 Amp fuse to BS 1362 should be fitted.

Note: A plug severed from the power cord should be destroyed, as a plug with bare conductors is hazardous in a live socket outlet (receptacle).

4

BM11D/21 Features and Controls 1/6/00 11:01 am Page 1

Features and Controls

Sliding Cover (open)

Mains Socket

Fuse FS1

Warnings

Cursor

Timer

HV Warning LED

On / Off Button

BM11D

Front Panel Layout

5

12 V Charger Input

Fuse FS2

Terminal Voltage

Cursor

Battery Symbol

Selector Keys

Test Button

BM11D/21 Features and Controls 1/6/00 11:01 am Page 2

Sliding Cover (closed)

Warnings

Timer

HV Warning LED

Selector Keys

On / Off Button

BM21

Front Panel Layout

Terminal Voltage

Battery Symbol

Cursor

Range Keys

Test Button

6

BM11D/21 Operation 1/6/00 11:03 am Page 1

Operation

INSTRUMENT CONTROLS

On/Off Button.

Pressing the On/Off button starts the instrument and initiates a self check and calibration. All LCD segments appear for 5 seconds, then the word ‘CAL’ appears for about 5 seconds.

When the word ‘CAL’ disappears, the instrument is ready for use, and is in standby mode. To switch the instrument off, press the on/off button once. (Auto switch off will occur after 10 minutes of non-use).

Selector Keys

The test voltage is selected by moving the cursor. When the test button is pressed the instrument will operate at the voltage indicated.

BM21 : In addition to the fixed test voltages the cursor can be used to select the variable voltage and test duration positions.

Range Keys ( BM21 only)

The range keys have two purposes. The first purpose is to select the measuring range, whether insulation resistance, leakage current or burn mode. The second function is indicated by two arrows which appear above the keys when either the variable voltage or test duration positions are selected. Using the range keys in this mode will raise and lower the applicable parameter. The change in voltage is shown at the top of the display, and the change in test duration is indicated in the bottom left hand corner of the display.

Test Button

Pressing the large ‘TEST’ button for more than one second will initiate a test at the selected voltage, simultaneously starting the timer. Pressing the button again will terminate the test and connect the internal discharge resistors across the output.

If more than 50 V exists across the terminals, this will be indicated on the display. If the current flowing into the terminals exceeds 2 mA it will not be possible to start a test.

A test may be terminated if;

1) The test time is exceeded.

2) The insulation under test suffers a complete breakdown.

3) The battery becomes exhausted.

4) Excessive electrical interference (>2mA at 5 kV) ( BM21 only).

Battery Symbol

When the battery is fully charged, all segments of the battery symbol will be indicated. As the battery is used the segments will recede. The symbol flashes when the battery capacity is excessively low (See ‘Battery’).

Cursor

The cursors on either side of the display indicate the ranges selected.

Condition and Warning Indication

Factors which may affect or inhibit a test are indicated by a large flashing cursor next to the appropriate warning label.

(See ‘Condition and Warning Indicators‘).

FS1: Mains input fuse.

FS2: Guard fuse.

12 V Charger input

The rechargeable batteries within the instrument can be charged from a 12 V supply. Connection is made through this socket. – +

Mains socket

To recharge the internal batteries a mains input of 95-265 V a.c.

7

BM11D/21 Operation 1/6/00 11:03 am Page 2

(50/60Hz) is required. The socket accepts a “Euro” plug.

Sliding cover

The sliding cover ensures that the input and the output terminals cannot be accessed simultaneously.

Terminals

The terminals marked ‘+’, ‘–’ and ‘G’ lock the test leads into the case to prevent accidental disconnection.

Terminal Voltage

At the end of a test, any voltage remaining on the terminals will be indicated until it has decayed to less than 50 V.

BM21 :Output terminal voltage is indicated during a test.

Timer

BM11D :The timer automatically starts when the test button is pressed. It indicates the time elapsed. Maximum test duration is

60 minutes, when the test will be stopped automatically.

BM21 : The test time can be set by the user. Selecting using the selector keys, and using the range keys to ramp the time up or down will set the duration of test. (Maximum 90 minutes). The timer will automatically start when the test button is pressed, and will stop when the test duration has elapsed

(unless stopped in one of the other ways). Setting the timer to zero minutes effectively disables the instrument. A test time of

10 minutes is useful for Polarisation Index (PI) testing.

For more information on PI testing, see ‘Application of Test

techniques’.

FEATURES

Automatic Discharge

Internal discharge resistors will be selected automatically

1) At the end of a test

2) If the instrument is switched off

3) If an internal error is detected

Variable Voltage ( BM21 only)

The variable voltage position provides the user with the option to select a non-standard voltage between 25 and 5000 V d.c.,or to continuously vary the voltage selected (in 25 V steps) during a test.

When operating on this range, the measurement range (either

‘R’, ‘I’ or ‘BURN’) cannot be changed. The measurement range must therefore be selected before the variable voltage position is chosen.

To select the test voltage required, move the cursor to the position and adjust the output terminal voltage using the Range keys. The terminal voltage is shown at the top of the display.

BURN Mode ( BM21 only)

Selecting ‘BURN’ mode will enable testing to continue after a breakdown, for fault location. Under some conditions, the breakdown will cause erratic display operation.The burn mode can only be selected before a test is started.

The detachable lid

Specially designed lid hinges enable the lid to be removed and replaced as required, and will protect the lid from strain or damage by unclipping itself if unintentionally opened past its full extent.

To replace the lid, hold it vertically and push the hinges back into their clips again while restraining the instrument. Then fold the lid shut.

8

BM11D/21 Operation 1/6/00 11:03 am Page 3

Operation

TESTING PROCEDURES

When not testing, i.e. when in standby mode, the instrument acts as a voltmeter.

1.

Select the required test voltage with the selector keys.

2.

To start a test, press the red test button for more than one second. The HV warning LED on the front of the instrument flashes, together with the display HV warning symbols.

When testing resistive or moderately capacitive loads (up to about 1 µF) the test voltage will appear within a few seconds.

On large capacitive items the voltage rise will be noticeably slower and on low resistance (less than 10 M

Ω

) the voltage may never rise to its nominal value.

Insulation resistance readings are updated once every second for readings up to about 100 M

Ω

. For readings between 1 G

Ω and infinity the sample rate will slow down to once every 20 seconds.

Changing the voltage during a test will upset the reading temporarily. The correct reading will appear when the new voltage has been stable over a full sample period.

3.

When the test is terminated the item under test will be automatically discharged. The test can be stopped manually by pressing the red test button. The test will be stopped automatically if the test duration is reached, the instrument is turned off, an internal error occurs, a fuse blows or if excessive noise is detected (except in Burn mode on the

BM21 ). When the test has stopped the final reading will be held on the digital display.

4.

( BM21 only) Pressing either of the selector keys will change the display to show the capacitance of the item under test.

N.B. The capacitance reading is only available if the test has

9 run for more than one minute, and provided the reading was not over-range.

Reading Limitations

The BM11/D can measure currents down to 10 nA. The highest digital readings obtainable are therefore 50 G

Ω at

500 V but rising to 500 G

Ω at 5000 V. The analogue display works at all voltages up to 1 T

Ω

.

The BM21 is considerably better at the high end of the scale.

The highest digital readings obtainable are 500 G

Ω at 500 V and 5 T

Ω at 5000 V. It is possible to read even higher resistances by switching from ‘R’ to ‘I’ mode (using the right

Range keys). The digital display then shows leakage current, resolving to 0.01 nA. Using this method it is theoretically possible to measure resistance up to 500 T

Ω at 5000 V but it will be necessary to perform an open circuit calibration test to establish measurement circuit offset current and test lead leakage. (This is ±0,2 nA at normal temperatures with new, clean test leads). Note that if the variable voltage has been selected, the decision to read ‘R’ or ‘I’’ must be made before the test is started.

BATTERY

The instrument is powered by two rechargeable, sealed, leadacid batteries. The state of charge is indicated by the battery symbol on the display. It is not possible to over charge or over discharge the batteries. When the last battery segment flashes there is very little energy left, probably less than 1 hour of testing. Turning the instrument off completely between tests will conserve the remaining battery energy. When batteries are completely exhausted the battery symbol will flash and the instrument will switch off. For maximum reliability, try to keep the batteries in a fully charged state and do not charge at extreme ambient temperatures. The batteries normally last

BM11D/21 Operation 1/6/00 11:03 am Page 4 about 5 years; less if subjected to high temperatures for much of the working day. To reduce the chances of sudden failure, two batteries are used, operating in parallel. If either battery fails, the instrument will continue to operate on the good battery but the ‘FS2’ indication will flash constantly. (See ‘Condition

and Warning Indicators’).

Charging the batteries should be done in a dry environment

(the instrument is not waterproof with the charging cover open).

Unplug the test leads and slide the charging cover open. (This operation renders the test lead sockets inaccessible and therefore prevents any danger of having the test leads connected to dangerous voltages). Connecting a.c. (50/60 Hz) voltages (95 V to 265 V) to the IEC socket will commence charging, which is indicated by the red lamp. An overnight charge will normally be sufficient. Turning the instrument on will show the state of charge.

It is possible to charge the batteries from a 12 to 15 V d.c.

supply using the round socket. However, this is slow and unlikely to provide a full charge. Applying more than 15 V is likely to overcharge the batteries.

Battery Charging Notes

1) Do not leave batteries in a totally discharged state

2) If instrument is not used, recharge the batteries for at least

24 hours every 6 months. (More frequently if the storage temperature is >40 °C).

3) 16 hours charging (from a fully discharged state) will achieve at least 90% of a full charge. It is beneficial to continue charging for several days and no harm will be done if the charger is left on indefinitely.

4) The battery should only be charged at temperatures in the range 0 °C to 40°C.

GUARD TERMINAL

The guard terminal is at the same voltage as the negative terminal. A fuse (FS2) protects the low impedance guard circuit from the application of external voltage. Guard fuse failure will be indicated on the display only when the guard circuit is in use. To check whether the fuse has blown, connect the positive terminal to the guard terminal and start a 500 V test. If the display flag flashes by ‘FS2’ the fuse has blown (see

‘Condition and Warning Indicators‘). FS2 is located in the charger recess.

Using The Guard Terminal

For basic insulation tests the guard terminal will not be used.

Most insulation tests can be performed by connecting the specimen between the ‘+’ and ‘–’ terminals. These tests will show up any deficiencies in the insulation, whether they are caused by leakage through the insulator body or across its surface.

To distinguish between body leakage and surface leakage the guard terminal ‘G’ may be used. In this way surface leakage current is removed before it enters the measurement circuit via the ‘–’ terminal.

Outer Sheath

Leakage path

Cable Core

Covering to ‘-’ terminal to ‘G’ terminal to ‘+’ terminal

10

BM11D/21 Operation 1/6/00 11:03 am Page 5

Operation

In cable testing, there may be a path of leakage across the insulation between the bared cable and the external sheathing, perhaps due to the presence of moisture or dirt. Where it is required to remove the effect of this leakage, particularly at high testing voltages, a bare wire may be bound tightly around the insulation and connected via the third test lead to the guard terminal ‘G’.

Since the leakage resistance is effectively in parallel with the resistance to be measured, the use of the guard causes the current flowing through the surface leakage to be diverted from the measuring circuit. The tester, therefore, gives more nearly the true insulation resistance.

CONDITION AND WARNING INDICATORS

FS2

A failed guard fuse will not be detected unless the guard terminal is in use. If the FS2 indicator flashes when the guard lead is in use it is likely that the guard fuse (FS2) has ruptured.

If the FS2 indicator flashes when the guard lead is not connected, it indicates failure of one of the batteries or a battery fuse (which is not accessible externally). The instrument will operate normally in this condition, although the operating time between charges will be reduced, no capacitance readings will be provided and no warning will be given if the guard fuse blows.

BREAKDOWN

The BM21 has a breakdown detector which terminates the test if a breakdown of the circuit occurs. The ‘BREAKDOWN’ indicator cursor will then flash to identify the cause of the test termination. Selecting the ’BURN’ mode prior to the test disables the ‘BREAKDOWN’ indicator.

The BM11D does not have a breakdown detector and is therefore effectively in permanent ‘BURN’ mode. When using the BM11D (or BM21 in ‘BURN’ mode) testing will continue if a breakdown occurs in the circuit under test. In very dry conditions, a high frequency arc can be generated. This may cause a disturbance to, and possibly a complete loss of the instrument display. In these circumstances it is important to remember that the circuit may still be energised.

If in any doubt, switch the instrument to ‘OFF’ and manually discharge the circuit before touching any connections.

EXT VOLTS

Display of the ‘EXT VOLTS’ cursor, indicates that the voltmeter is reading a voltage which originates from an external source.

The voltmeter will show d.c. voltage of either polarity or a.c.

voltage.

NOISE ( BM21 only)

If an external interference (normally 50 Hz or 60 Hz hum current) is excessive (>2 mA at 5 kV), testing will terminate, and the noise indicator will flash.

(Note: trips at approx. 1,5 mA at <2 kV).

Error Numbers

Internal faults and errors will cause the display to show ‘E’ followed by a number. These error numbers can be invoked by extreme cases of electromagnetic interference or by internal faults, in which case the number is of little significance. The only meaningful error numbers are E5 and E11 which indicate that a negative current has been measured.

Calibration Errors

At switch-on there is a calibration check which automatically

11

BM11D/21 Operation 1/6/00 11:03 am Page 6 adjusts the measurement system against an internal voltage and resistor. The calibration sequence will not finish unless the measurement system is giving consistent results within preset limits.

If the startup screen does not progress beyond the segment check or stops with ‘CAL’ displayed, calibration has failed.

12

BM11D/21 Application Notes 1/6/00 10:59 am Page 1

Application Notes

Preventive Maintenance

The proverb ‘A stitch in time saves nine’ inspired the title of an

AVO International booklet on insulation testing, as it neatly sums up the benefits of preventative maintenance. The savings come in financial terms from costly repairs, lost production, lost profits and in human terms, from lives saved in the event of dangerous electrical faults.

Regular insulation testing of electrical equipment can help to detect deteriorating insulation. The effects which cause insulation to deteriorate include mechanical damage, vibration, excessive heat or cold, dirt, oil, moisture and localized voltage stresses - all of which can arise on most industrial or utility equipment.

Insulation tests are sometimes used in isolation as absolute measures of the quality of the insulation. This is most appropriate when equipment is being installed and checked for compliance with a specified ‘Pass’ level. For operational equipment the key factors are trends in the insulation readings.

It is therefore important that records of insulation readings are kept, relating to each piece of equipment or ‘Asset’ in your testing regime. AVO supplies test record cards to assist with such record keeping.

There are also a number of influences on the insulation readings - temperature, humidity and surface leakage for example and a range of test techniques have been developed to help with the interpretation of your insulation tests.

13

Test Record Example

BM11D/21 Application Notes 1/6/00 10:59 am Page 2

Insulation Testing Concepts

Insulation resistance can be considered by applying Ohm’s Law.

The measured resistance is determined from the applied voltage divided by the resultant current, R = V

I

There are two further important factors to be considered.

These are (i) the nature of the current through and/or over the insulation, and (ii) the length of time for which the test voltage is applied. These two factors are linked. The total current that flows is made up of three separate currents:-

1.

Capacitance charging current. This current is initially high and drops as the insulation becomes charged up to the applied voltage.

Components of insulation test current

3.

Conduction or Leakage current.This is a small steady current that can be sub-divided into two:-

(a) A current flowing along conduction paths through the insulation material.

(b) A current flowing along conduction paths over the surface of the insulation material.

As the total current depends upon the time for which the voltage is applied, Ohm’s Law theoretically applies at infinite time.

The charging current falls relatively rapidly as the equipment under test becomes charged up. The actual length of time depends upon the size and capacitance of the item under test.

Larger items with more capacitance will take longer e.g. long supply cables. The absorption current decreases relatively slowly compared with the charging current. In essence it depends upon the nature of the insulation material.

The conduction or Leakage current builds up quickly to a steady value and then remains constant for a particular applied voltage under stable conditions. It is this current that is affected by moisture, dirt etc. and the degree to which it flows bears a direct relation to the quality of the insulation, and consequently to the value of the insulation resistance measured. An increase in the leakage current is a pointer to possible future problems.

2.

Absorption current. This current is also initially high but drops at a much slower rate than the charging current.

14

BM11D/21 Application Notes 1/6/00 10:59 am Page 3

Application Notes

Short time or Spot Test

This is the simplest insulation test, giving a reading of insulation resistance in M

Ω

. The test is applied for a short but specific period of time, immediately after which a reading is taken. The time is typically 30 or 60 seconds and the BM21 will allow you to set this time and the test will finish automatically. The reading will not necessarily be the maximum value but if the same time is used each test, then the same point on the curve of increasing apparent resistance is being compared. On installation these readings will be compared to the required minimum specification. Further readings taken for maintenance purposes must be monitored for any trend that they show. The readings are subject to variation from temperature and humidity and these factors may require the insulation reading to be corrected. Information on temperature correction is given in the

AVO publication ‘A Stitch in Time’. Alternatively, a Polarization

Index (PI) test may be used.

Polarization Index (PI) Test

This test method is a particular example of the time resistance method. Time resistance tests take successive readings at specified times and are independent of temperature.

They can often help in the situation where past test record frequency are limited.

Good insulation generally shows an increase in resistance over a 10 minute period.

MΩ

0 Time 10 Minutes

With contaminated insulation, absorption effects are masked by high leakage currents and the readings are therefore fairly flat.

The PI test takes the ratio of the values at 10 and 1 minutes this is the Polarization Index. The PI test also has the advantage of not requiring temperature correction. The value of

PI can give a rough guide to condition of insulation, although the figures should always be interpreted in the context of the equipment history and your experience.

PI TEST RESULT

<1,0

1,0 to 2,0

2,0 to 4,0

>4,0

INSULATION CONDITION

Unsatisfactory

Dubious

Good

Very Good

There are two specific conditions to be aware of when interpreting PI tests results, particularly if a history of the equipment is unavailable.

1) Dry, brittle insulation (e.g. on windings) on can give a high

PI but fail under shock conditions.

2) If multi-layered insulation fails in one of the layers while the others retain high resistances, the effect on the test current will tend to increase the PI value, masking possible problems from surface leakage caused by dirt and contamination.

15

BM11D/21 Application Notes 1/6/00 10:59 am Page 4

Stress Considerations

Measurement above 100 GΩ

Figure 1. shows the stresses and subsequent leakages which will occur between the test leads if neither is connected to earth (ground). These leakages have significant effect and occur through the air itself.

Figure 3. shows a problem which can occur. If one end of the sample is grounded and this is required to be connected to the positive terminal, then the negative (measurement) lead is surrounded by a 5 kV field. This is likely to cause at least 1 nA of unwanted leakage current, representing a 5 T

Ω resistance in parallel with the sample under test.

Figure 1.

Figure 2. shows the effect of connecting the guard lead to the ground. This reduces the stray leakage into the negative

(measurement input) terminal considerably, but this technique is only permissible if the item under test is isolated from the ground. (‘Isolated’ means insulated by a resistance of at least 5 M

Ω for the positive terminal or 10 k

Ω for the negative terminal).

Figure 3.

When taking measurements above 100 G

Ω therefore, the user should where possible ground the Guard Lead as shown in figure 2, otherwise parallel leakage paths may occur.

Figure 2.

16

BM11D/21 Specification 1/6/00 11:05 am Page 1

Specification

Test Voltages (d.c.):

Accuracy (0 °C to + 30 °C):

Insulation Range:

Accuracy (0 °C to + 30 °C):

500 V, 1000 V, 2500 V & 5000 V

BM21 only ; 50 to 5000 V variable in 25 V steps

±5% of nominal test voltages (load resistance >100 M

Ω

)

100 k

Ω to 1 T

Ω analogue

BM11D : 10 k

Ω to 500 G

Ω digital

BM21 : 10 to 5 T

Ω digital

BM11D : ±5% 1 M

Ω to 100 G

Ω

±5% 1 M

Ω to 10 G

Ω

±20% outside these limits (above 100 k

Ω

)

BM21 : ±5% 1 M

Ω to 1T

Ω

±5% 1 M

Ω to 100 G

Ω

±5% 1 M

Ω to 10 G

Ω

±20% outside these limits (above 100 k

Ω

) at 5 kV at 500 V at 5 kV at 500 V at 50 V

For extended temperature range -20°C to + 50°C the percentage error doubles

Short Circuit Current: mA nominal

2

Resistance under test (Ω)

17

BM11D/21 Specification 1/6/00 11:05 am Page 2

Typical Terminal Voltage Characteristics

18

BM11D/21 Specification 1/6/00 11:05 am Page 3

Specification

Timer:

Hum Rejection:

Voltage range:

Accuracy (0 °C to +30 °C):

Guard Terminal:

Capacitor charging time:

Capacitor discharging time:

Maximum continuous overload:

Temperature coefficient:

Temperature range:

Power supply:

Environmental protection:

Altitude:

Fuses:

Safety:

E.M.C:

19

BM11D : 0 to 60 minutes

BM21 : 0 to 90 minutes: User selects test duration

1 mA rms per kV test voltage

2 mA rms maximum

BM11D : 50 to 1000 V a.c. or d.c.

BM21 : 50 to1000 V a.c. or d.c.

(N.B. Display does not distinguish between V a.c. and V d.c.)

±2% ±1 V

Will guard out parallel resistances to a minimum of 250 k

Ω

.

When measuring 100 M

Ω under these conditions, the additional error will be less than 5%.

5s per µF to charge to 5 kV

2s per µF to discharge to <50 V

1 kV rms

0,2% per °C (test current >100 nA)

0,1% per °C for test voltage

Operating: -20 °C to +50 °C (Errors double outside range 0 to 30 °C)

Storage: -25 °C to +65 °C

Two 12 V, 2 Ah Lead-acid rechargeable batteries. Recharge time: 16 hours

Battery life: typically 8 hours continuous testing

IP54 (with the charging recess cover securely closed)

2000 m max. to operate within specification

FS1: 100 mA (T), 250 V IEC 127/1

FS2: 100 mA (F), 250 V IEC 127/1

Mains Power cord fused plug (when applicable): 3 A fuse to BS 1362

The instruments meet the requirements for double insulation to IEC 1010-1 (1995) EN

61010-1 (1995) to installation Category III* , 300 Volts phase to earth (ground) and 500

Volts phase to phase

The instruments meet EN 50081-1 and EN 50082-1 (1992)

BM11D/21 Specification 1/6/00 11:05 am Page 4

Supplied with the instrument

User Guide

HV lead set, 3 m long

Set of 3 High voltage test leads, 3 m long

Part Number

6172-033

6121-403

Accessory Pouch

Mains (line) power cord

6420-096

Available as an optional extra

HV lead set, 8 m long (x3) 6121-451

6121-452 HV lead set, 15 m long (x3)

12V d.c.charging lead with automotive cigarette lighter plug, 3 m long. 6231-584

5 kV Shielded Lead set

5 kV Calibration Box - CB101

Carrying case

Publications

‘A Stitch in Time’

6311-080

6311-077

AVTM21-P8B

Cat. Number (US only)

(210968)

(218748)

20

BM11D/21 Rep & Warranty 1/6/00 11:03 am Page 1

Repair and Warranty

The instrument circuit contains static sensitive devices, and care must be taken in handling the printed circuit board. If the protection of an instrument has been impaired it should not be used, and be sent for repair by suitably trained and qualified personnel. The protection is likely to be impaired if, for example, the instrument shows visible damage, fails to perform the intended measurements, has been subjected to prolonged storage under unfavourable conditions, or has been exposed to severe transport stresses.

New Instruments are Guaranteed for 1 Year from the Date of Purchase by the User.

Note: Any unauthorized prior repair or adjustment will automatically invalidate the Warranty.

Approved Repair Companies

A number of independent instrument repair companies have been approved for repair work on most M E G G E R ® instruments, using genuine MEGGER® spare parts. Consult the Appointed Distributor / Agent regarding spare parts, repair facilities and advice on the best course of action to take.

Returning an Instrument for Repair

If returning an instrument to the manufacturer for repair, it should be sent freight pre -paid to the appropriate address. A copy of the Invoice and of the packing note should be sent simultaneously by airmail to expedite clearance through

Customs. A repair estimate showing freight return and other charges will be submitted to the sender, if required, before work on the instrument commences.

Instrument Repair and Spare Parts

For service requirements for MEGGER ® Instruments contact:-

AVO INTERNATIONAL or

Archcliffe Road

Dover

Kent, CT17 9EN.

England.

AVO INTERNATIONAL

Valley Forge Corporate Centre

2621 Van Buren Avenue

Norristown PA 19403

U.S.A.

Tel: +44 (0) 1304 502243

Fax: +44 (0) 1304 207342 or an approved repair company.

Tel: +1 (610) 676-8579

Fax: +1 (610) 676-8625

21

BM11D/21 Back Cover 1/6/00 11:00 am Page 1

Archcliffe Road

Dover

Kent, CT17 9EN.

England.

Tel: +44 (0) 1304 502100

Fax: +44 (0) 1304 207342

AVO

INTERNATIONAL

P.O. Box 9007

Valley Forge

PA 19484-9007

U.S.A.

Tel: +1 (610) 676-8500

Fax: +1 (610) 676-8610

4651 S. Westmoreland Road

Dallas

TX 75237-1017

U.S.A.

Tel: +1 (800) 723-2861 (U.S.A. only)

Tel: +1 (214) 330-3203 (International)

Fax: +1 (214) 337-3038

Megger SA

29 Allée de Villemomble

93340 Le Raincy

Paris, France

Tel: +33 (1) 43.02.37.54

Fax: +33 (1) 43.02.16.24

This instrument is manufactured in the United Kingdom.

The company reserves the right to change the specification or design without prior notice.

MEGGER is a registered Trade Mark of AVO INTERNATIONAL LIMITED.

Copyright © AVO INTERNATIONAL LIMITED.

Part No. 6172-033 - Edition 8 - Printed in England - 6EE

LEET