| 摘要 |
1279649 Automatic temperature control systems ROBERTSHAW CONTROLS CO 29 Sept 1969 [30 Sept 1968] 47838/69 Heading G3R A temperature control system employing sequential energization of a series of heaters 11, 13 &c. comprises a thermostat 187 which when closed below a determined temperature energizes a thermal switch 31 which completes a circuit to heater 11 also a second thermal switch 33, which after a period of time completes the circuit to second heater 13 and third thermal switch 35 et seq. On opening of thermostat 187 the thermal switches are de-energized in the same sequence. A current through any line 105, 115 &c. induces a voltage through a core 213 in a winding 211 which provides a firing potential to a thyristor 201 operating a relay 191, 205 controlling a fan 207 which blows air over elements 11, 13 &c. A thermal delay switch 61 allows a relay 91 to rapidly open its contacts on the power failure and to reclose only after a time delay on reinstatement of supply. Bucking strips 112, 116, &c. are provided to give a snap open action to the thermal switches. The system may be employed for water heating, in which case an over temperature switch 97 may be provided. An A.C. supply (not shown) is connectible to lines 55, 57. |
