A three phase transformer winding resistance meter, the Vanguard TRM-403 Transformer Resistance Meter allows the user to connect all test cables to the transformer bushings. The unit will then measure the transformer resistance value for each of the phases without the need to disconnect and reconnect cables for each phase.
For a Delta transformer, the Vanguard TRM-403 can measure the phase resistance readings and provide the individual Delta winding resistance values. The Vanguard TRM-403 can also provide the individual winding resistance values for a Wye transformer without the neutral terminal.
If the transformer winding resistance temperature is available at the time of testing, the Vanguard TRM-403 can calculate the equivalent resistance value at any temperature value. This useful feature can be used to compare the field readings against the factory test resistance values.
The Vanguard TRM-403 can perform a special test to collect data automatically for up to 90 minutes (at 60-second sampling intervals) or 45 minutes (at 30 second sampling intervals). The test data is recorded with a time stamp.