Current Transformer Test Set EZCT S2

The EZCT S2 is Amperis' second-generation, microprocessor-based, current transformer test set. The EZCT S2 can perform the current transformer (CT) excitation, CT current-ratio, and winding polarity tests automatically. The EZCT S2 automatically raises and lowers the excitation test voltage without any operator intervention. With up to 1500 Vac excitation test voltage available, the EZCT S2 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 S2. 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 builtin 4.5-inch wide thermal printer.

CT Ratio and Polarity Tests

The EZCT S2 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 currentratio 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 S2 features a back-lit LCD screen (4 lines by 20 characters) that is viewable in both bright sunlight and low-light levels. A rugged, alpha-numeric, membrane keypad is used to control the unit.

Thermal Printer

A built-in 4.5-inch wide thermal printer can print the current transformer test report and plot the excitation curves.

Test Record Header Information

The test record header information can include the company name, substation name, circuit ID, manufacturer, CT serial number, operator's name, and test record comments. In addition to the test record header, a 20-character test description for each test in the record can also be entered.

Internal Test Record Storage Capacity

The EZCT S2 can store up to 140 test records in Flash EEPROM. Each test record may contain up to 10 excitation curves, current-ratio readings, and winding polarity readings. Test records can be recalled and printed on the built-in thermal printer.

Internal Test Plan Storage Capacity

The EZCT S2 can store up to 128 CT test plans in Flash EEPROM. A test plan defines the excitation test voltage and current selection, CT nameplate ratio, and CT winding terminal connection instructions for each test. Up to 10 test definitions can be stored in each test plan. The use of a test plan greatly simplifies the CT testing process since it also provides instructions for making the proper CT cable connections. Test plans can be created on the EZCT S2 itself or created on a PC and downloaded to the EZCT S2 via the unit's built-in RS-232C or USB ports.

Computer Interface

The EZCT S2 can be used as a stand-alone unit or can be computercontrolled via the built-in RS-232C or USB interfaces.A Windows® XP/Vista-based CurrentTransformer Analysis software application isprovided with each EZCT S2. This software can be used to retrieve test records from the EZCT S2, create test plans, download test plans to the EZCT S2, and can also be used to run CT tests from the PC. Tabulated test records can be exported in Microsoft® Excel® format