INSTA Thermistors are manufactured in accordance with DIN 44081 and 44082. Due to their small thermal mass, they have favorable temperature sensitivity.
INSTA Thermistors should be placed as near as possible to the hot spot: In three phase motors, one Thermistor should be embedded in each phase. Good thermal coupling between Thermistor and winding is essential. The PTC Thermistors should be inserted parallel to the winding. The resistance increases sharply in the region of the nominal response temperature.
In this way the mechanical stresses on the PTC Thermistors during forming the end turns of overhang winding can be minimized. Shrink cap is especially well suited for this because of its mechanical stability. Response times ≤ 5 sec. are achieved with INSTA Thermistor.
PTC thermistors are temperature dependent resistors manufactured from barium titanate and should be chosen when a drastic change in resistance is required at a specific temperature or current level. PTCs can operate in the following modes:
- Temperature sensing, switching at temperatures ranging from 60°C to 180°C, e.g. protection of windings in electric motors and transformers.
- Solid state fuse to protect against excess current levels, ranging from several mA to several A (25°C ambient) and continuous voltages up to 600V and higher, e.g. power supplies for a wide range of electrical equipment.
- Liquid level sensor.
The unique patented design Composite Thermistor contains 2 NTC and 1 PTC thermistors and has a resistance temperature characteristic similar to a single NTC but with a region of constant resistance.
