Voltech AT3600 User Manual page 334

T T
RANSFORMER ESTS
1.32. STRW – S
W
The Stress Wattage test tests the transformer for breakdown of insulation by
measurement of the energising power of a winding, usually the primary, with the
remaining windings open circuit. This test applies the voltage, usually twice the
normal operating voltage, and continually measures the power to determine any
breakdown by changes in the measurement.
This test is suitable for sub-miniature line frequency, large line frequency bobbin
wound and some HF transformers. It checks the integrity of interturn insulation, the
magnetic material and joints.
M
A constant voltage source is applied to the winding under test. Both the rms voltage
and the power are measured. If necessary, the voltage can is trimmed to the user
specified value, and the measurement repeated. The measurement is repeated many
times until the dwell time has elapsed. The result given is the measured power.
Usually, the energization is at twice the working voltage and frequency, and has the
purpose of trying to create an inter-turn breakdown at a point of potential weakness in
the wire enamel. This breakdown is detected by an increase in the measured power.
P 7.1.54.
AGE
U
HERE SED
EASUREMENT
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TRESS ATTS
C
ONDITIONS
VPN 98 - 024
V AT3600 U
OLTECH SER
T T C
ESTS AND EST ONDITIONS
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ANUAL