GE Intellix BMT 330 Installation Manual page 56

27. For each Bushing Adaptor input, measure the resistance across the pins of the terminals
as show in Figure D-16. Record this measurement as [R2] in the Results table. It should be
less than 2000 Ω and within 5 % of the input channel impedance in Calibration > PCB >
Phase Voltage > Input Impedance. Refer to the Intellix™ BMT 330 Service Manual.
Figure D-16: R2 resistance measurement
28. Reconnect all the coaxial cables.
29. Retest the resistance across the two screws of the connector as shown in Figure
D-15 for each Bushing Adaptor. Record this measurement as [R3] in the Results
table.
30. Ensure that the measurement of [R3] is within 5% of the total input resistance
[R ] calculated from [R1] and [R2] for each input.
input
Note:
31. Store a completed copy of the Results table with the transformer maintenance
documents.
32. Once the transformer is energised and the grounding switches are in the
operational position (not grounded), measure the voltage drop across the core and
the shield at the block terminals of the coaxial cables connected to the Bushing
Adaptors and record these voltages in the Results table. These voltages must be
within 0.9 to 1.4 Vrms.
Note:
MA-017 – BMT 330 Installation Manual – Rev 3.3
The total input resistance [R
This does not apply to the neutral inputs.
] is calculated as [R
input
]=1/(1/[R1] + 1/[R2])
input
4-Mar-22 Page 56 of 69