| 摘要 |
A refrigeration and active damper control circuit uses a single-pole thermostatic switch to control the damper motor for the fresh food compartment of a refrigeration unit. When the thermostatic switch is closed, the control circuit connects current from the electrical power source directly to the damper motor through the thermostatic switch; when the thermostatic switch is open, the control circuit connects current from the electrical power source through the evaporator fan motor and then through the damper motor. The damper motor has an electrical resistance substantially larger than that of the evaporator fan motor, so that during the latter series connection of the evaporator fan motor and damper motor, a sufficient voltage drop develops across the damper motor so that the damper will be closed by the damper motor. Since the evaporator fan motor is used to connect current to the damper motor when the thermostatic switch is open, it is not necessary to use a dual-pole thermostatic switch to control the damper motor. Rather, only a single-pole thermostatic switch will suffice. This substantially reduces the cost of the control circuit, and may also improve reliability.
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