SETUP AND CONNECTIONS
AVTMTTR310 Rev 8 May 2016
25
Current Transformers (CTs)
Connections to CTs are made backwards compared to power or potential
transformers. The H terminals on the test set must be connected to the X
terminals on the CT; and the X terminals on the test set must be connected to
the H terminals on the CT.
NOTE: Dots on the housing of the transformer are commonly used to identify
terminals of the same polarity.
WARNING
Failure to observe proper connections will result in a safety
hazard and may result in damage to the test set or CT. Failure to
observe voltage rating of low-current X winding may result in
damage to the CT.
CAUTION
Never use AUTO mode of operation when testing the current
transformers with the rated voltage below 80 V ac.
Most of the CTs are tested at 8 V ac excitation voltage.
NOTE: Most of the current transformers are tested at 8 V ac excitation
voltage. Some current transformers with turn ratio of 100:5 and less get
saturated at 8V ac. They require lower excitation voltage for testing and
therefore can not be tested with the Cat. No TTR310. Use the TTR100 or
TTR25.
Unmounted CTs
1. Connect the wing-nut ground terminal of the test set to a low-impedance
earth ground using the 15-ft (4.6 m) ground cable supplied.
2. Use the TTR310 H and X test leads and connect as follows and as shown in
Figure 5-5.
3. Connect the heavy-duty clips marked H1 and H2 of the test lead to the
respective X1 and X2 terminals of the CT.
4. Connect the heavy-duty clips marked X1 and X2 of the test lead to the
respective H1 and H2 terminals of the CT. Ensure correct polarity.
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