Holding Temp vs Functioning Temp in Thermal Cutoffs

Thermal cutoffs and thermal protectors are used in many consumer products and bear various marks, certifications, and approvals. These are meant to be the last resort of protection since these do not reset once tripped. Common applications include hair dryers, irons, heaters, electric motors, microwave ovens, refrigerators, hot coffee makers, dishwashers, and battery chargers to name a few.

When you are looking at Thermal Cutoffs you will typically see 2 ratings displayed, holding temperature and rated functioning temperature.

The Holding Temperature is the safe temperature range for the using the cutoff. The ambient temperature should not rise over the holding temp rating during normal use.

The Rated Functioning Temperature is the temperature at which the thermal element in the cutoff will melt and open the circuit permanently.

  • Note: This is an ambient temperature rating.

Here is a picture from Cantherm that shows how the internal circuit operates.
image

Many of these thermal cutoffs also have a Maximum Temperature Limit. If this limit is exceeded there could be damage to the thermal cutoff that may cause damage and potentially undesired operation.

imageimageimage

Applicable Part numbers

P10917-ND P10912-ND 317-1135-ND 317-1129-ND 317-1133-ND 317-1130-ND 317-1142-ND 317-1128-ND 317-1134-ND 317-1554-ND 317-1560-ND P10907-ND P10925-ND P10921-ND P10920-ND 317-1138-ND 317-1125-ND 317-1136-ND 317-1126-ND 317-1127-ND 317-1132-ND 317-1139-ND 317-1124-ND 317-1564-ND 317-1562-ND 749-1130-2-ND 749-1130-1-ND 749-1129-2-ND 749-1129-1-ND 317-1568-ND 317-1569-ND 317-1556-ND 317-1567-ND 317-1563-ND 317-1561-ND 317-1555-ND 317-1557-ND 317-1558-ND 317-1566-ND 317-1565-ND 317-1559-ND 285-1901-ND EYP-2BH145-ND EYP-05BE134-ND EYP-2BN099-ND EYP-05BE101-ND 317-1123-ND 317-1131-ND 317-1137-ND 317-1140-ND 317-1141-ND MTR1R95-ND MTR1R105-ND MTS1S95-ND MTS1S105-ND MTS1S125-ND MTS1S138-ND MWS1S95H-ND MWS1S105H-ND MWS1S125H-ND MWS1S138H-ND RTP200HR010SA-ND MWS2S95-ND MWS2S105-ND L50NG913-240-ND L50NG913-240-600MM-ND TJD-ND P10906-ND P10908-ND P10909-ND P10910-ND P10911-ND P10913-ND P10914-ND P10915-ND P10916-ND P10918-ND P10919-ND P10922-ND P10923-ND P10924-ND P10926-ND P10927-ND P10928-ND P10929-ND P10930-ND P10931-ND P10932-ND P10933-ND P10934-ND P10935-ND P10936-ND 317-1143-ND MTR1R125-ND MTR1R138-ND MTR1R145-ND MWS2S125-ND MWS2S138-ND RTP200R060SA-2TR-ND RTP200R060SA-2CT-ND RTP200R060SA-2DKR-ND
EYP-2BN082 EYP-1BF115 SDF DF144S SDF DF100S SDF DF128S SDF DF104S SDF DF240S SDF DF098S SDF DF141S L5018424DELB0XE L5012824DELB0XE EYP-05BE115 EYP-2BN143 EYP-2BN110 EYP-2BN109 SDF DF184S SDF DF077S SDF DF152S SDF DF084S SDF DF091S SDF DF119S SDF DF192S SDF DF072S L5010024DELB0XE L5011024DELB0XE HCTF235L150000BR00 HCTF235L150000BR00 HCTF235L055000BR00 HCTF235L055000BR00 L5007724DELB0XE L5007224DELB0XE L5016724DELB0XE L5008424DELB0XE L5010424DELB0XE L5011924DELB0XE L5017024DELB0XE L5015224DELB0XE L5014424DELB0XE L5009124DELB0XE L5009824DELB0XE L5014124DELB0XE DFP10112 EYP-2BH145 EYP-05BE134 EYP-2BN099 EYP-05BE101 SDF DF066S SDF DF110S SDF DF170S SDF DF216S SDF DF228S MTR1 R95 MTR1 R105 MTS1 S95 MTS1 S105 MTS1 S125 MTS1 S138 MWS1 S95H MWS1 S105H MWS1 S125H MWS1 S138H RTP200HR010SA MWS2 S95 MWS2 S105 L50NG913-240 L50NG913-240-600MM TJD EYP-05BE102 EYP-05BE130 EYP-05BE133 EYP-05BE139 EYP-1BF102 EYP-1BF130 EYP-1BF133 EYP-1BF139 EYP-1BF168 EYP-2BN088 EYP-2BN098 EYP-2BN124 EYP-2BN126 EYP-2BN135 EYP-2BN163 EYP-2BN183 EYP-2MT092 EYP-2MT092A EYP-2MT092B EYP-2MT098 EYP-2MT098A EYP-2MT098B EYP-2MT102 EYP-2MT102A EYP-2MT102B SDF DF220S MTR1 R125 MTR1 R138 MTR1 R145 MWS2 S125 MWS2 S138 RTP200R060SA-2 RTP200R060SA-2 RTP200R060SA-2