T100 is a platinum thermal resistance, its resistance to temperature change is proportional to the. The relationship between the resistance and temperature change for PT100 PT100: when the temperature is 0 degrees centigrade its resistance is 100 ohms, at 100 DEG C when its resistance of about 138.5 ohms. Industrial it principle: when the PT100 in his 0 degrees Celsius when resistance is 100 ohms, its resistance will rise with temperature and uniform growth.