Qualitrol 509ITM Series, Manual

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The relay delay timer may require a value that would be derived through experience with the
transformer because:
• the direct winding measurement will react at a faster rate than the calculated winding
temperature, and
• the calculated value is based on data from the original heat run and is heavily
dependent upon the accuracy of this data.
In the above example, relay will actuate if:
• the Direct Measurement minus the Calculated Value exceeds 10 degrees, or
• the Direct Measurement minus the Calculate Value falls below -5 degrees.
Important:
Because of the variance in the temperature throughout the windings depends
on the location of the probe, measuring the winding temperature is unlikely to
perfectly match the calculated winding temperature. But the two values should
track relative to each other with time and conditions. Therefore, when
commissioning the 509 DW, taking some time to monitor the different winding
measurements is recommended to set the tracking window for the relay
matrix. This data can also be used to improve the winding temperature model.