GB1109464A - Improvements in or relating to overheating protection circuits - Google Patents
Improvements in or relating to overheating protection circuitsInfo
- Publication number
- GB1109464A GB1109464A GB3781064A GB3781064A GB1109464A GB 1109464 A GB1109464 A GB 1109464A GB 3781064 A GB3781064 A GB 3781064A GB 3781064 A GB3781064 A GB 3781064A GB 1109464 A GB1109464 A GB 1109464A
- Authority
- GB
- United Kingdom
- Prior art keywords
- thermistor
- resistance
- supply
- transistor
- conducting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
- H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
- H02H7/0852—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load directly responsive to abnormal temperature by using a temperature sensor
Landscapes
- Thermistors And Varistors (AREA)
- Protection Of Generators And Motors (AREA)
Abstract
1,109,464. Protective arrangements. STANDARD TELEPHONES & CABLES Ltd. 10 Sept., 1965 [16 Sept., 1964], No. 37810/64. Heading H2K. In a protective arrangement for an electrical machine comprising a positive temperature coefficient thermistor PTC in thermal contact with the machine and a semi-conductor device which, on increase of the resistance of the thermistor, changes its state to control means for interrupting the supply to the machine, a latching circuit is connected to the semiconductor device to prevent its automatic return to its original state when the resistance of the thermistor falls, but which after the interruption and on resumption of the supply permits the semi-conductor device to assume the state appropriate to the resistance of thermistor. In Fig. 2 the semi-conductor device is a transistor T 1 which is normally non-conducting, but conducts when the resistance of the thermistor PTC increases and causes a further transistor T 2 to stop conducting. A relay A is de-energized and opens its contacts to interrupt the supply to the protected machine and at contacts A 3 removes a short-circut from a capacitor C 1 . The capacitor C 1 becomes charged and the potential across it is sufficient to latch the transistor T 1 in the conducting state. When the supply is interrupted the capacitor discharges and on resumption of the supply the resistance of the thermistor determines which transistor conducts. In the arrangement of Fig. 3 (not shown) both transistors are normally conducting and control the firing of a silicon controlled rectifier in series with the coil of a contactor. The latching circuit includes a third transistor.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3781064A GB1109464A (en) | 1964-09-16 | 1964-09-16 | Improvements in or relating to overheating protection circuits |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3781064A GB1109464A (en) | 1964-09-16 | 1964-09-16 | Improvements in or relating to overheating protection circuits |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1109464A true GB1109464A (en) | 1968-04-10 |
Family
ID=10399166
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB3781064A Expired GB1109464A (en) | 1964-09-16 | 1964-09-16 | Improvements in or relating to overheating protection circuits |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB1109464A (en) |
-
1964
- 1964-09-16 GB GB3781064A patent/GB1109464A/en not_active Expired
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