| 摘要 |
A condition responsive switching apparatus with an alarm feature for use in refrigeration appliances, such as freezers or the like. The switching apparatus includes a contact operator which moves between first, second, and third positions in response to the pressure changes of a bellows. The bellows pressure increases and decreases in response to changes in temperature sensed at the appliance. The apparatus includes a first set of control contacts to provide energization of a compressor and a second set of alarm contacts to provide energization of an alarm circuit. The contact operator has a first dog which opens and closes the control set of contacts as the operator moves through a snap action increment of travel between the first and second positions. An alarm spring opposes the travel of a second dog of the contact operator beyond the second position with a preload force until the excess of the snap action energy of the operator is dissipated. The alarm spring, thereafter, opposes the contact operator with a spring gradient until the operator reaches the third position and closes the alarm contacts. The closure of the alarm contacts causes the energization of an alarm circuit which signals that the appliance temperature is in excess of the cycling temperature and that the failure of a system component is likely to have occurred.
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