B59052D1110A040 Replacement Epoxy Coated Ring Lug Terminal Disk PTC Temperature Sensor 110C

B59052D1110A040 Replacement Epoxy Coated Ring Lug Terminal Disk PTC Temperature Sensor 110°C

Application Of The PTC Temperature Sensor 110°C

Limit temperature:

Motor protection

Overtemperature protection

Selection Table Of The PTC Temperature Sensor 110°C

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PTC thermistors as limit temperature sensors 

With PTC thermistors as temperature sensors only the steep region of the R/T characteristic is used. The resistance of the PTC thermistor is to be regarded as a function of the ambient temperature [RPTC = f (TA)].

The precondition for this relationship between resistance and ambient temperature is that selfheating and/or the varistor effect are excluded. This means that these PTC thermistors must be operated in the lowest possible field strengths. To enable a fast response, thermistor sensors have especially small dimensions. High control accuracy is achieved by using materials with an extra steep resistance/temperature characteristic.

Limit temperature measurement for industrial applications

A PTC thermistor can be used effectively to detect whether a temperature limit in industrial equipment, liquids, etc. is exceeded. The PTC thermistor is mounted in thermal contact with the medium that has to be protected from overheating. When the rated temperature limit of the medium is reached, the resistance of the PTC thermistor increases abruptly. In connection with a control unit, this signal can be used to automatically switch off the power supply of a load. AMPFORT offers leaded disks, metal tags, screw-type metal cases as well as surface-mounted devices.

Limit temperature sensor for power semiconductors

Power semiconductors, for example in DC/DC converters or in dimmers for lighting, produce a lot of heat in relation to their (small) dimensions. If heat transfer is restricted or impeded, for instance by fan failure or excessive ambient temperature, this can quickly lead to damage or destruction of the semiconductor or surrounding components. A PTC thermistor sensor makes it possible to intervene in operation of the power stage directly and with a measured response in the event of excess temperature. When the temperature exceeds the temperature limit of the semiconductor (e. g. a power transistor or thyristor), the resistance of the thermistor increases, resulting in a reduction of the power applied to the semiconductor. This prevents the semiconductor from overheating.

The thermistor must be thermally coupled to the semiconductor and placed in its current control circuit. For this purpose EPCOS offers SMD PTC thermistor versions.

Figure 15 Principle circuit diagram for the protection of power semiconductors by a PTC thermistor limit temperature sensor

PTC sensors for motor and machine protection

PTC thermistors are widely employed as temperature sensors in electrical machines to monitor winding temperature. In this case, the PTC thermistor is wound directly into the winding so that direct thermal contact is produced. AMPFORT offers special types that conform to DIN 44081 and DIN 44082 and that can be designed in with Siemens tripping units. The abrupt increase in the resistance of the thermistor at high temperatures can be used as a control signal for the tripping unit. To detect the temperature at several phases, thermistors should be connected in series. AMPFORT offers standard single and triple sensor versions as well as custom assemblies. Available sensing temperatures range from 60 to 180 °C.

Figure 14 Schematic circuit diagram of the protection of a three-phase electric motor with a triple PTC thermistor sensor assembly