In testing a three-phase delta-connected winding for an open circuit using a ohmmeter, what must be done?

Correct Answer: Option C — if possible, open the delta-connections to avoid shunting the phase being tested

When testing delta-connected windings with an ohmmeter, the windings form parallel paths. If the connections are not opened, the meter will measure the resistance of the path being tested in parallel with the other two phases, leading to inaccurate, lower-than-actual resistance readings that mask an open circuit in one phase.