Chapter 1 — Introduction
September 2004
Page 5
power transformers have an inductance over
1000 henrys
.
Therefore, minute changes in current will result in
undesirable voltage swings that can make it impossible to
measure the DC resistance of the transformer windings.
The ADWEL DWR-10 addresses this challenge in several
ways, so that the instrument can achieve stable resistance
readings on the largest transformers in record time.
•
The DWR-10 uses a powerful, highly regulated, and
filtered constant current source to drive current
through the windings.
•
It uses a 10 A (30 V) source, which is enough to
drive the core quickly into saturation where small
changes in current have no effect on the measured
resistance.
•
By connecting the primary and secondary windings
in series, the speed of saturation and stability of the
readings is increased because there are more amp-
turns contributing to the flux in the core. The
resistance measurement of both windings is made at
the same time on channels A and B.
The instrument works best when the transformer core has
been driven into saturation by the DC current. In this
condition, the readings stabilize quickly and are not
affected by small changes in current.
All manuals and user guides at all-guides.com