NDB Technologies CTT Series User Manual page 41

9.6 Potential Transformer (PT, VT)
This section explains how to connect the CTTx5 or CTTx2 to test a potential
transformer (PT or VT).
The CTT is able to perform the following tests on a voltage transformer: Insulation
resistance, winding resistance, polarity, phase deviation and ratio. Since PTs are not
designed to handle saturation due to the lower voltage in comparison with the PT's
nominal voltage ratings, it is expected that the saturation curves will not display
any inflection or knee point.
To test a PT using the CTT, the operator of the instrument must remember one
important physical character of CTs vs PTs:
• CTs will step down currents from the primary to the secondary. Therefore CTs
will step up voltage from the primary to the secondary.
• PTs will step down voltage from the primary to the secondary. Therefore PTs
will step up current from the primary to the secondary.
H1
C T T S e r i e s
Refer to section 8.2 for automatic mode operation.
X1 clip
Make sure not to select the saturation test.
H1 & H2
clamps
H0
GND
X1 X2
Control Cabinet
- U s e r M a n u a l
X2 clip
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