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The Megger BM11D 5-kV Insulation Resistance Testers are portable, battery-powered, high-voltage
instruments that use the latest electronic design and technology. The instruments have user-friendly keypads
with push-buttons to select test voltages of 500, 1000, 2500, and 5000 V dc. In addition to the standard test
voltages, a variable voltage feature on the BM21 selects test voltages between 25 and 5000 V dc in 25-V steps.
An integral timer automatically controls the duration test and stops the output voltage when the preset time has
expired. Analog/digital displays offer practicality and precision. The analog/digital LCD on the BM11D displays from 100 kΩ to 1 TΩ in all test voltages. On the BM21, the analog/digital LCD displays readings of insulation resistance to 5 TΩ, leakage current to below 1 nA, and capacitance to 10 µF. The analog scale rapidly identifies insulation condition and monitors variable measurements. The digital display complements the analog scale by simultaneously displaying an easy-to-read, precise measurement. As a safety feature, these testers act as an ac/dc safety voltmeter, indicating the level of applied voltage before a test and monitoring discharge voltage after a test. For added safety, an alarm warns the operator if the circuit under test has not been de-energized. Both testers incorporate a guard terminal to eliminate the effects of surface leakage in the item under test, thus ensuring accurate measurements.
APPLICATIONS
The BM11D test the insulation resistance of:
■ High-voltage power cables
■ Large motor/generator windings
■ Line and substation transformers
■ High-voltage buses
Both instruments perform spot tests, step-voltage tests, and
dielectric absorption tests for the following applications:
■ Acceptance testing at installation to check conformance
to specifications.
■ Routine preventative/predictive maintenance testing after
installation.
■ Quality assurance testing as part of the manufacturing
process.
■ Diagnostic testing to isolate faulty components for
repair.
The BM11D and BM21 detect high- or low-resistance
grounds and short circuits in apparatus, cables, wiring,
caused by moisture, oil, dirt, corrosion, damage to
insulation or natural deterioration. The units determine the
presence of moisture, solvents and semi conducting foreign
materials in wires, cables and other conductors, and in
built-up insulation systems such as those found in motor
windings. |
