| 摘要 |
A thermally-responsive electrical control for an electric heater of a water boiling container includes a switch-on-dry protector switch unit electrically connected with the cold leads of the heater and having a thermally sensitive switch means effective, in use, to interrupt the electrical supply to the heater should the element overheat through being switched-on when the container is dry. A removable steam-sensitive unit is mounted on the protector switch unit and includes an overcenter spring mechanism and a thermally-responsive actuator for the mechanism. The actuator of the said steam sensitive unit is arranged to impinged by vapor or steam issuing from the outlet of a passage leading to the interior of the container, and the electrical parts of the control are shielded from such vapor or steam. A mechanical link is provided between the overcenter spring mechanism and the switch means of the protector switch unit so that tripping of the overcenter spring mechanism by the actuator serves to operate the switch means of the protector switch unit. The steam-sensitive unit is optional and may be deleted to allow the switch-on-dry unit alone to control the heater. |
