Doble M4100 High Voltage Apparatus Tester

Trusted and deployed all across the globe, the Doble M4100 set standard for power apparatus testing. The M4100’s unique combination of test capabilities and artificial intelligence software makes it the power industry’s most trusted Power Factor/Tan Delta instrument. Testing with the M4100 is simple and accurate thanks to the Doble Test Assistant (DTA) software. Once installed the user can analyze test results with the help of FRANK™, the First Response Analytics Knowledgebase, which provides clear recommendations and explanations.


  • Power Factor/Tan Delta testing to confirm insulation integrity and quality
  • Capacitance testing to measure physical changes that may have occured to the apparatus
  • Turns ratio testing to detect shorted turns or winding damage
  • Leakage reactance/short circuit impedance testing to evaluate winding deformation
  • Single phase excitation current testing to evaluate the transformer magnetizing circuit
  • Capacitor bank testing to detect deteriorating or failed capacitors within a bank
  • Easy and accurate testing with Doble Test Assistant (DTA) software


  • Safety is our priority with safety switches, power strobes and ground earth relay interlocks
  • Eliminates the effect of varying electrostatic interference with patented Line Frequency Modulation, which makes measurements at a frequency above and below the system frequency
  • Reliability & Accuracy – generates its own clean test signal using an internal waveform generator for reliable results and stable readings
  • Software firmware system senses abnormal current, temperature and voltage operation even before a user would notice
  • Instantly analyze your test results, providing clear recommendations and explanations with FRANK™, the First Response Analytics Knowledgebase


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