Product Description
The AVO Megger BM21 5kV Insulation Resistance Tester is a portable, battery powered, high voltage insulation tester. The instrument’s user friendly keypad with push buttons, allows the user to select test voltages of 500, 1000, 2500 and 5000 VDC. In addition to the standard test voltages, a variable voltage feature selects test voltages between 25 and 5000 VDC in 25V steps. An integral timer automatically controls the duration test and stops the output voltage when the preset time has expired. Analogue/Digital displays offer practicality and precision. The Analogue/Digital LCD shows readings of insulation resistance to 5TΩ, leakage current to below 1nA and capacitance to 10μF. The analogue scale rapidly identifies insulation condition and monitors variable measurements. The digital display compliments the analogue scale by simultaneously displaying an easy to read, precise measurement. As a safety feature, the BM21 acts 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 when the circuit under test has not been de-energized.
The BM21 incorporates a guard terminal to eliminate the effects of surface leakage in the item under test, thus ensuring accurate measurements..
The BM21 tests the insulation resistance of:
• High Voltage power cables
• Large motor/generator windings
• Line and substation transformers
• High Voltage buses
The instrument performs spot tests, step-voltage tests, and dielectric absorption tests for the following applications:
• Acceptance testing at installation to check conformance to specifications
• Routine preventive/predictive maintenance testing after installation
• Quality assurance testing as part of the manufacturing process
• Diagnostic testing to isolate faulty components for repair
The instrument detects high- or low-resistance grounds and short circuits in apparatus, cables and wiring, caused by moisture, oil, dirt, corrosion, damage to insulation or natural deterioration. The BM21 determines the presence of moisture, solvents and semiconducting foreign materials in wires, cables and other conductors, and in built-up insulation systems such as those found in motor windings. A series of measurements taken and recorded over time show the gradual decline in insulation integrity during its operational life. The maintenance engineer or technician uses this information to anticipate future performance and to plan for repairs. These recorded measurements also show improvements in the insulation of motor, transformer, and generator windings that result from drying-out procedures after exposure to excessive humidity or water.
The instrument features
• Simple, push button operation is user-friendly and easy to use.
• Analogue/digital LCD enables direct reading in all ranges.
• Lock down TEST button and integral timer are useful for extended tests such as polarization index.
• Rechargeable, battery-powered instrument is portable anywhere.
• Automatic discharge of capacitive test sample charge promotes user safety.
• Guard terminal eliminates surface leakage current from the measurement.
