An NTC thermistor is always connected in series with the load to be protected. If the inrush current cannot be handled by one thermistor alone, two or more thermistor elements can be connected in series. (EPCOS AG)

Typical power converters made by other manufactures require the user to add external inrush current limiting components such as an NTC thermistor. In contrast, all BEAR converters have active inrush current limiting circuitry built into the module. (Bear Power Supplies)

The trips are caused by the initial start up current - or inrush current - which can be several times greater than their operating or steady-state current. In a three-phase motor, for example, inrush current generally lasts between 75-150 milliseconds with a current spike between 500% and 1200%. (Fluke Corporation)