MEWOI MEWOI1500D, Manual

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-17-
【
Err
】
:
It indicates that the tester can’t identify
phase-angle difference and polarity properly, because
the principal machine may not receive the signal from
HV or LV terminals, or be interfered by the channel
signal, or the signal amplitude may be much weak.
The 1st current can remain being displayed on the
R-phase.
【
Ratio
】
:the ratio between the 1st and 2nd measured
current ;
【
Transformation
】
: It is first to calculate the multiple
between the measured secondary current and its
default value of 5A, based on the benchmark of
secondary current, and then transform the primary
current to a value according to the multiple; the
transformed value is as same as the measured
value. It is available to set the benchmark of
secondary current in the range from 0.00A to 99.99A.
【
CT ratio of transformation based on benchmark
of 10kV-YY
】
: the HV detector collects the secondary
current from the busbar (380V) of transformer;
transform the primary current (10kV) of transformer
based on the benchmark of 10kV/380V, and then
calculate the ratio between the primary current and
secondary current.
1) TEST OF CT RATIO, PHASE-ANGLE DIFFERENCE, AND
POLARITY
As above described, the tester enters into the CT ratio
measurement mode after starting, vise the primary and secondary
circuit of CT with HV detector and three-channel LV current clamp
respectively, and the principal machine displays the four current
values in same screen simultaneously, and detects the
phase-angle differences and polarity.
For example: The pretest current transformer is a LV terminal CT
of 10kV/380V transformer, which primary circuit current is 151.5A,