QUALITROL AKM345 GEN3 OTIWTI
TM
Instruction Manual
40-08847-00-Rev001
www.qualitrolcorp.com
Page 25 of 34
7.
Winding Temperature Simulation
The AKM345 GEN3 contains a method to simulate the temperature of a winding by indirect measurement referred
to as thermal image. This is a frequently used simulation method that measures top oil temperature and biases
the winding temperature indicator reading proportional to transformer load to indicate winding temperature.
The AKM345 uses this method by utilizing the probe to measure top oil temperature, an internal heating element
to provide the winding temperature bias, a matching resistance to adjust the current supplied to the heating
element, and the current proportional to transformer load provided by the bushing current transformer (CT).
The matching resistance is used to adjust the current needed by the heating element to provide the required
winding temperature gradient delivering a parallel path to divert part of the total current. There are 3 internal
matching resistance models (TD50, TD76, and TD50/5) and 2 external matching resistance models (AKM 44674
and AKM 44678).
Internal Matching Resistance TD50, TD76, and TD50/5 Technical Data
AKM345 TD Adjusting Schematic
