Vanguard EZCT-2000B - Manual (Page 6)

EZCT-2000B USER’S MANUAL REV 1
2
1.0 INTRODUCTION
1.1 General Description and Features
The EZCT-2000B is Vanguard’s third-generation microprocessor-based current transformer test
set. Designed specifically for CT testing, the EZCT-2000B has the following outstanding features
that can greatly increase productivity and save time during the commissioning stage:
• Performs CT excitation, current-ratio, polarity, and phase angle tests
• Measures insulation resistance and winding resistance of the CT secondary windings
• Measures the CT’s secondary burden
The EZCT-2000B’s test leads can be connected to all the CT output terminals, and the complete
CT test can be performed automatically without any operator intervention.
Saturation Test
The CT saturation test is performed in compliance with the ANSI/IEEE C57.13.1 and IEC 60044
standards. Test voltage ranges from 50, 300, 500,1200 and 2000 Vac can be selected for the
saturation test. The test voltage is raised and lowered automatically by the EZCT-2000B. The
saturation test voltage and current data is collected and stored in the EZCT-2000B’s internal
memory. Knee point voltages (ANSI 10/50, IEC 10/50, IEEE-30, IEEE-45) are calculated and
printed on the test report.
All of the EZCT-2000B’s test leads can be connected to the CT output terminals (X1, X2, X3, X4
and X5), and there is no lead switching required during testing. This convenient arrangement
allows for testing any of the 10 possible combinations of X1 to X5. Up to 10 saturation tests can
be stored in one record. Once the test is completed, the test report and CT excitation curves
can be printed on the built-in thermal printer.
CT Ratio and Polarity Test
The CT current-ratio is determined using the ANSI/IEEE C57.12.90 measurement method. A test
voltage is applied on any two terminals (X1 to X5) of the CT, and the induced voltage is
measured through the H1 and H2 terminals of the CT. The CT current-ratio is displayed and also
stored in memory. The current-ratio is measured from 0.8 to 5,000. The CT winding polarity is
displayed as a “+” sign (in-phase) or a “-” sign (out-of-phase) and is annotated with the phase
angle in degrees. The CT current-ratio error and phase displacement is also calculated based on
the CT burden (or rated power) and rated current.
CT Winding Resistance Test
The EZCT-2000B can measure the DC resistance of the CT winding under test. The DC winding
resistance reading range is from 100 micro-ohms to 10 Ohms. Equivalent winding resistance
values at different temperatures are also provided in the report.
CT Winding Insulation Resistance Test
The EZCT-2000B can also measure the insulation resistance of the CT’s secondary winding using
a test voltage up to 1000 Vdc. The DC winding resistance reading range is from 2 to 500 Mega-
ohms. The insulation resistance test results are displayed and printed on the report.