Atec BM User Manual

BM11, BM11D, BM21 and BM25

5 kV Analogue/Digital Insulation Testers

BM11, BM11D, BM21 and BM25

5 kV Analogue/Digital Insulation Testers

n Spot tests and diagnostic insulation tests

n Simplicity and Ease of Use

n User safety features

n Unique rugged casing

n Analogue and Analogue/Digital Displays

n Wide range of test voltages

DESCRIPTION

The Megger® BM11 series of 5 kV Insulation Testers
provides a choice of features to suit all applications and
budgets.

The traditional BM11 instrument became the industry-
standard 5 kV tester. It is battery-powered, housed in a
rugged case and has a large, simple white-on-black scale.

The series has been extended with three analogue/
digital instruments; the BM11D, BM21 and BM25. These
instruments show results and test options on a large, clear
analogue/digital scale for both practicality and precision. A
built-in timer makes both spot tests and PI testing easier to
carry out.

They are powered by a built-in rechargeable lead-acid
battery which can be charged directly from any supply from
95 V to 265 V. All testers incorporate a guard terminal to
allow surface leakage to be removed.

Pre-set standard test voltages at 500 V, 1000 V, 2500 V and
5000 V are supplemented on the BM21 and BM25 units
with a variable test voltage in 25 V steps. These top of the
range units also allow measurement of resistance to 5 TΩ,
leakage current to 0,01 nA and can display capacitance at
the end of a test to 10 µF.

The BM25 extends the diagnostic testing capability of the
range by performing automatic Polarisation Index, Step
Voltage and Dielectric Discharge tests as well as providing
an optically isolated RS232 port for downloading results
during a test.

APPLICATIONS

The BM11 series is designed for testing the insulation of
high voltage electrical equipment and the wide voltage
range also allows it to be applied to low voltage
equipment.

Generators, motors, transformers, cables and switchgear all
require effective maintenance and the test techniques on
the Megger range give valuable diagnostic information.

‘Spot’ Insulation tests that are the most widely used, check
on the general condition of electrical insulation, called up
in most standards covering equipment design, testing,
installation and maintenance.

Insulation suffers from gradual steady decline, as well as
occasional sudden damage; the effects of dirt, grease,
moisture, vibration and chemical attack can be tracked
through the recording of Polarisation Index tests which
remove the temperature dependence of raw Insulation
Resistance measurements.

For finding more localised insulation problems, the BM25
includes both Step Voltage and Dielectric Discharge tests.
Step Voltage identifies local weak spots because they
respond differently as the electrical stress is increased,
while the Dielectric Discharge test can show up a single
bad layer in multilayer insulation.

The key to Predictive Maintenance is the trending of
diagnostic tests and this is facilitated on the BM25 by the
ability to use a PC to store results over time for trend
analysis.

BM11, BM11D, BM21 and BM25

5 kV Analogue/Digital Insulation Testers

FEATURES AND BENEFITS

All BM11 Series

n Choice of test voltages

n Direct reading display

n Unique rugged case

n Guard terminal

n Designed for user safety

BM11D

n Large, custom Analogue/Digital LCD

n Built-in timer

n Locking test leads for safety

n Battery indicator

n Automatic discharge of capacitance

n Voltage measurement and warning

n Tests to 500 GΩ

n Weather proof to IP54

BM11 BM11D

Features

n Large direct reading analogue scale n Large Analogue/digital display

n Guard terminal n Built-in timer
n Rugged case design n Locking test leads for safety
n 123 mm scale length n Battery indicator
n Weatherproof to IP54
Note: Not for sale in E.U. n Voltage measurement and warning

Test voltages (d.c.) 500, 1000, 2500, 5000 V 500, 1000, 2500, 5000 V

Accuracy (20°C) ±5% on open circuit ±5% on 100 MΩ load

Insulation 100 kΩ to 100 GΩ; at all test voltages Digital 10 kΩ to 50 GΩ @ 500 V
Resistance 10 kΩ to 100 GΩ @ 1000 V
Range 10 kΩ to 250 GΩ @ 2500 V
10 kΩ to 500 GΩ @ 5 kV
Analogue 100 kΩ to 1 TΩ @ all voltages

Basic Accuracy ±1,5% of arc length ±5% of reading 10 MΩ to 100 GΩ @ 5 kV

Short Circuit
Current 1 mA nominal, 2 mA max. 1,8 mA nominal, 2 mA max.

Voltage Range 50 to 1000 V d.c. or a.c. 50 to 1000 V d.c. or a.c.

Accuracy (20°C) ±5% ±10 V ±2% ±1 V

Display Analogue Analogue/digital (3 digits)

Interference
Rejection 2 mA a.c. (50/60 Hz) on 5 kV range 1 mA r.m.s. per kV to a maximum 2 mA

Capacitor
Discharge Time <1 s per µF to discharge from 5000 V to 50 V <2 s per µF to discharge from 5000 V to 50 V

Leakage current
measurement None None

Capacitance
measurement None None

Timer None Automatic; 0 to 60 minutes

Temperature Operating -15 to +55°C (5 to +131°F) Operating -20to +50°C (-4 to 122°F)
Range Storage -40 to +65 °C (-40 to +149°F) Storage -25 to +65 °C (-13 to +149°F)

Temperature
Coefficient < 0,04% of arc length per °C (0.2%/°F) (Applies over range 0 to 30°C) (32 to 86°F)
0,2% per °C (0.1%/°F) for test currents >100 nA 0,1% per °C to test voltage (0.05% per °F)

Humidity Range 90% RH @ 40°C max. (104°F) 90% RH @ 40°C max. (104°F)

Safety IEC348 IEC1010-1 (1995), EN61010 (1995) to installation
category III, 300 V, phase to earth, 500 V phase to phase

BM11, BM11D, BM21 and BM25

5 kV Analogue/Digital Insulation Testers

BM21: as BM11D plus;

n Variable test voltage in 25 V steps

n Breakdown or ‘Burn’ modes allow choice of diagnostic

approach

n Shows capacitance at end of test

n Timer sets test duration for easier test control

n Tests to 5,000 GΩ

n Leakage current mode

BM25: as BM21 plus;

n Automated testing for increased productivity

n Polarisation Index and Step Voltage tests

n Dielectric Discharge test for multilayer insulation

n Optically isolated RS232 port for real-time download

BM21 BM25

All BM11D features plus: All BM21 features plus:

n Variable test duration controlled by timer n RS232 real time download
n Variable test voltage in 25 V steps to 5000 V n Dielectric Discharge Test
n Leakage current and capacitance measurement n Automatic Polarisation Index Tests
n Breakdown or Burn modes n Automatic Step Voltage Tests
n Tests to 5,000 G

Test voltages (d.c.) 500, 1000, 2500, 5000 V; plus 25 to 5000 V in 25 V steps

Accuracy (20°C) ±5% on 100 MΩ load ±25V for test voltages <500 V

Insulation Digital 10 kΩ to 500 GΩ @ 500 V
Resistance 10 kΩ to 1 TΩ @ 1000 V
Range 10 kΩ to 2,5 TΩ @ 2500 V
10 kΩ to 5 TΩ @ 5 kV
Analogue 100 kΩ to 1TΩ @ all voltages

Basic Accuracy ±5% of reading 1 MΩ to 1 TΩ @ 5 kV (0 to 30°C) (32 to 86°F)

Short Circuit
Current 1.8 mA nominal, 2 mA max.

Voltage Range 50 to 1000 V d.c. or a.c. (0 to 5000 V d.c. when testing)

Accuracy (20°C) ±2% ±1 V

Display Analogue/digital (3 digits)

Interference
Rejection 1 mA r.m.s. per kV to a maximum 2 mA

Capacitor
Discharge Time <2 s per µF to discharge from 5000 V to 50 V

Leakage current
measurement 0,01 nA to 999 µA Accuracy ±5% ±0,2 nA

Capacitance
measurement 0,01 - 10,0 µF (displayed at end of test) Accuracy ±15% ±0,03 µF

Timer User selectable 0 to 90 minutes. Test is terminated at end of preset time

Temperature Operating -20 to +50 °C (-4 to 122 °F)
Range Storage -25 to +65 °C (-13 to +149 °F)

Temperature
Coefficient (Applies over range 0 to 30 °C) (32 to 86 °F)
0,2% per °C for test currents >100 nA

Humidity Range 90% RH @ 40°C max. (104°F)

Safety IEC1010-1 (1995), EN61010 (1995) to installation
category III, 300 V, phase to earth, 500 V phase to phase

BM11, BM11D, BM21 and BM25

5 kV Analogue/Digital Insulation Testers

SPECIFICATIONS

See Specifications Table.

BM11

Power Supply

NiCd battery pack of 2 Ah
capacity. Battery life: typi­cally 8 hrs continuous (varying
between 2 h and 20 h depending
upon load conditions). Battery
charging: built-in-charging
unit, operating from 100 V to
250 V a.c. supply, 50 Hz or
60 Hz, charging time: 16 hrs.

Low battery voltage indication:
small oscillations of the
pointer occur with an approx.
80% exhausted battery, large
pointer oscillations occur when
the battery must be recharged.

Dimensions

344 mm x 245 mm x 158 mm

1

⁄2 in x 95⁄8 in approx.)

(13

Weight

4,8 kg (10

1

⁄2 lb approx.)

BM11D, BM21 &
BM25

Power Supply

Rechargeable sealed lead-acid
batteries (12 V, 4 Ah).
Battery life typically 8 hrs
continuous testing.
Built in charger operates from
95 V to 265 V a.c.,
recharge time: 8 hrs to 90%,
16 hrs to 100%
d.c. emergency charge socket
from 12 V d.c.
Comprehensive battery state
indicator on display.

EMC

In accordance with IEC61326
including amendment No.1

Altitude to 2000 m to retain
full accuracy

CB101 CALIBRATION
BOX

Nominal resistance
values:

10 MΩ, 100 MΩ, 1 GΩ and
10 GΩ.

High quality resistors, rated
to high voltage, suitable for
calibration checks on insulation
testers up to 5 kV d.c. Voltage
coefficient is less than 1 part
per million per volt.

A calibration certificate is
provided with each CB101
showing the actual value of
each resistance check-point.

CB101
SPECIFICATION

Calibration accuracy
1%
Voltage coefficient
1 ppm/V
Calibration temperature
20 °C
Temperature coefficient
250 ppm/°C (139 ppm/°F)
Shelf stability, typically
0,5% per year

Environmental specifica­tion

Operating temperature
+5 to +40 °C (41 to 104 °F)
Storage temperature

-20 °C to +60 °C (-4 °F to
140 °F)
Operating humidity
60% RH max.

ORDERING INFORMATION

Item (Qty) Order No.

Analogue Insulation Tester BM11
Analogue/Digital Insulation Tester BM11D
Analogue/Digital Insulation Tester BM21
Automated 5 kV Insulation Tester BM25

Included Accessories BM11

3 x 3m HV leads 6220-317
Mains Supply lead for charging 25424-860
Accessory pouch, leather 6430-193
User Guide 6172-922

Included Accessories BM11D/BM21/BM25

High Voltage test lead, 3 m long (set of 3) 6121-291
Mains supply lead for charging 25424-860
Accessory pouch 6420-096
PC connector lead, 1,8 m long (BM25 only)
(9 way D female to 9 way D female) 25955-025
BM25 Download 31⁄2” disk (BM25 only) 6139-085
Test Record Cards (5) 6172-112
User Guide

Optional Accessories BM11

High Voltage test lead, 8 m long 6220-318

Optional Accessories BM11D/21/25

3 x 8m HV leads 8101-182
3 x 15m HV leads 8101-183
Shielded test leads 15 m long TBA
Charging lead, 12 V d.c. with automotive
cigarette lighter plug 3 m long 6231-584
CB101 Calibration Box 6311-077
Test Record Cards (pack of 20) 6111-217

Publications

‘A Stitch in Time” AVTM21-P8B
‘The Lowdown on High Voltage d.c. Testing’ AVTM22P-1

Optional Accessories

Test leads with fused prods, FPK4 —
unsuitable for continuity measurements: comply
with Health and Safety Executive Guidance Note
GS 38 (1 set) 6111-287

Typical Terminal Voltage
Characteristics

Dimensions

344 mm x 245 mm x 158 mm

1

⁄2 in x 95⁄8 in approx.)

(13

Weight

5,6 kg (12

UK

Archcliffe Road Dover
CT17 9EN England
T [phone]
F [phone]

1

⁄2 lb approx.)

Safety

Meets the requirements of
EC1010-1 (1992), EN61010
(1993) to installation category
III, 300 V, phase to phase

EMC

In accordance with IEC61326
including Amendment No. 1.

UNITED STATES

4271 Bronze Way
Dallas TX 75237-1088 USA
T 800 723 2861 (USA only)
T [phone]
F [phone]

OTHER TECHNICAL SALES OFFICES

Norristown USA, Toronto CANADA,
Mumbai INDIA, Trappes FRANCE,
Sydney AUSTRALIA, Madrid SPAIN
and the Kingdom of BAHRAIN.

Registered to ISO 9001:2000 Reg no. Q 09290

Registered to ISO 14001 Reg no. EMS 61597

BM11_11D_BM21_25_DS_en_V13

www.megger.com
Megger is a registered trademark