Vanguard EZCT-2000A - Manual (Page 6)

EZCT-2000A USER’S MANUAL REV 1
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1.0 INTRODUCTION
1.1 General Description and Features
The EZCT-2000A is Vanguard’s third-generation microprocessor-based current transformer test
set. The EZCT-2000A can perform the current transformer (CT) excitation test, measure the CT
winding resistance and CT current-ratio automatically. All of the EZCT-2000A’s test leads can be
connected to the CT output terminals (X1, X2, X3, X4 and X5), eliminating the need for lead
switching during testing. Test voltage output is automatically raised and lowered by the EZCT-
2000A without any operator intervention. With up to 2000 Vac excitation test voltage available,
the EZCT-2000A 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, 300 Vac, 500 Vac, 1200 Vac or 2000 Vac)
can be selected, and then the test voltage is raised and lowered automatically by the EZCT-
2000A. The excitation test voltage and current data is collected and stored in the unit’s internal
memory. Any of the 10 possible combinations of X1 to X5 can be tested since all of the unit’s
test leads can be connected to all of the CT output terminals at the same time. Up to 10
excitation tests can be stored in one record. 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 Test
The EZCT-2000A determines the CT current-ratio using the ANSI/IEEE C57.12.90 measurement
method. A test voltage is applied on any two terminals of the CT (X1 to X5), and the induced
voltage is measured through the CT’s H1 and H2 terminals. The CT current-ratio is displayed on
the screen and stored in memory. The current-ratio measuring range is from 0.8 to 5,000 to 1.
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.
CT Winding Resistance Test
The EZCT-2000A can also measure the DC resistance of the CT winding under test. The DC
winding resistance measuring range is from 100 micro-ohms to 10 ohms.
User Interface and Display
The EZCT-2000A 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.