Vanguard EZCT-S2A - Manual (Page 6)

EZCT S2A USER’S MANUAL REV 1
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1.0 INTRODUCTION
1.1 General Description and Features
The EZCT S2A is Vanguard’s third-generation, microprocessor-based, current transformer test
set. The EZCT S2A can perform the current transformer (CT) excitation, CT current-ratio, and
winding polarity tests automatically. The EZCT S2A automatically raises and lowers the
excitation test voltage without any operator intervention. With up to 1500 Vac excitation test
voltage available, the EZCT S2A can easily perform excitation tests on very large CT’s.
Excitation Test
The CT excitation test is performed using the ANSI/IEEE C57.13.1, IEC 60044-1 test method. The
test voltage range for the CT excitation test (50 Vac, 250 Vac, 500 Vac, or 1500 Vac) can be
selected, and then the test voltage is raised and lowered automatically by the EZCT S2A. The
test voltage and current data are collected and stored in the unit’s internal memory. Up to 10
CT excitation and current-ratio tests can be stored in one test record. IEEE-30, IEEE-45, ANSI/IEC
60044-1 (10/50) knee point voltages are also calculated and printed on the test report. Once
the test is completed, test results can be printed and excitation curves can be plotted on the
built-in 4.5-inch wide thermal printer.
CT Ratio and Polarity Tests
The EZCT S2A determines the CT current-ratio using the ANSI/IEEE C57.12.90 measurement
method. A test voltage is applied to the CT’s secondary terminals and the induced voltage is
measured through the CT’s H1 and H2 terminals. The CT current-ratio and polarity are displayed
on the screen and stored in memory. The current-ratio measuring range is 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.
User Interface and Display
The EZCT S2A features a back-lit LCD screen (240 x 128 dot graphic) that is viewable in both
bright sunlight and low-light levels. A rugged, alpha-numeric, membrane keypad is used to
control the unit.
Built-in Thermal Printer
A built-in 4.5-inch wide thermal printer can print the current transformer test report and plot
the excitation curves.