Megger TTR320 Series, Instruction Manual

Page: 24 / 68

M
AVTMTTR320-EN Rev A Oct 2008
16
and Y3) of the transformer under test. Refer to Table 4-2 for test lead
markings. With delta connected windings, X0 is not used. With wye
connected windings, a neutral connection for X0 is normally available.
5. On/OFF Switch. It is only after all of the above connections are safely
made and all safety precautions of sections 2 and 3 are satisfied, should the
On/OFF switch be turned to the ON position.
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.
F
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.
G CAUTION
Never use AUTO mode of operation when testing the
current transformers with the rated voltage below80 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 TTR320. For this case, use
the TTR100 or TTR25.
Unmounted CTs
1. With the ON/OFF Switch in the OFF position, make the circuit
connections as described in Section 3.2.
2. Connect the H and X test cables to the respective H and X receptacles of the
TTR320. Make sure that the connectors are securely fastened (using
clockwise rotation) to the receptacles.