| 摘要 |
A pump for spraying an anti-freezing liquid on a conveyor belt exposed to freezing temperatures is controlled by an electric circuit containing a timer, a relay provided with a normally open switch, and a normally open thermostat that closes to start the timer when the ambient temperature falls below a given low temperature. The relay is connected in series with the timer switch and the thermostat to close the relay switch when both the timer switch and the thermostat are closed, whereby the pump will be operated until the timer times out or the thermostat reopens. If desired, the relay can be omitted.
|
