High temperature motors, (HT- prefix) are provided with class H insulation systems. This insulation begins to melt at 180 degrees Centigrade. The heat generated by the motor must be subtracted away from the melting point of the insulation to obtain the maximum allowable ambient temperature. The ability of the motor to dissipate heat into the environment will also affect the maximum allowable ambient temperature. In typical stepper motor applications these motors will operate successfully up to +155 degrees C (refer to FAQ regarding heat losses). Provided the change in temperature does not exceed 10 degrees C. per minute, these motors can be used in a very wide range of temperatures. The HT series products without modifications are useful from 0 to about +155 (see heat loss details). For temperatures from 0 to -20 C most of the HT products can be used, but different lubrications are required. From -20 to -40 C some select products are suitable. Consult the factory before ordering. For temperatures lower than -40 C refer to Cryogenic products.