NDB Technologies CTT Series User Manual page 6

C T T S e r i e s - U s e r M a n u a l
3. Introduction
The CTTx5 and CTTx2 are designed to efficiently perform current transformer testing.
The CTT design is focused on providing the results required for commissioning and
maintenance of protection class CT's.
Protection class CT's are designed to provide proportional current signal outputs
even when sensing large fault type currents. These proportional signals are what
the protection relays will require to ensure reliable operation. The CTT performs
the following tests: CT excitation voltages and knee points, turns ratio and error %,
polarity, phase angle, winding resistance, insulation resistance and also measure
the CT's load burden (Ohms/VA). The knee point voltages are calculated for ANSI
10/50, IEEE-30 and IEEE-45.
The CTTx5 differs from the CTTx2 in that it has X1, X2, X3, X4 and X5 test terminals
whereas the CTTx2 has X1 and X2 terminals. The CTTx5 provides convenient
arrangement for testing any of the 10 possible combinations of a multi ratio current
transformer X1 to X5. Up to 10 set of tests can be stored in one test file.
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