After a DC current test, such as a winding resistance measurement, the magnetic core of a power or instrument transformer may be magnetized (remanent magnetism). Also , when disconnecting a transformer from service, some amount of magnetic flux trapped in the core could be present. The remanent magnetism can cause various problems such as erroneous diagnostic , inaccurate measurements on a transformer, or an inrush current at a start-up of power transformer, or an incorrect operation of protective relays due to magnetized CT cores. To eliminate this source of potential problems, demagnetization should be performed. When suspecting remanent magnetism, or when various test results, like FRA or magnetization/excitation current, show possible remanency, a DEM60 C can be used to perform fully automatic demagnetization. Transformer magnetic core demagnetization requires alternating current applied with magnitude decreasing to zero. The DEM60C provides this alternating current by internally changing the polarity of a controlled DC current. During the demagnetization process the instrument supplies a current at decreasing magnitude for an each step, following a proprietary software solution.
DV Power Features:
- Fully automatic demagnetization
- Demagnetization currents 5 mA – 60 A DC
- Demagnetization progress graph
- Automatic discharging circuit
- Lightweight – 13,1 kg