| 摘要 |
Various functions of a production oil well are monitored to cause a switch closure for each normal cycle of the pump. Alternatively, the level of the fluid within the well is monitored to cause the switch closure. The switch closure activates a first oscillator whose count is compared with a variable frequency oscillator over a given period of time to ascertain the percentage of time of normal operation. The integrated time is adjusted to shut down the system when the percentage of time drops to or below the preselected amount. In response to the integration timer signal, a shutdown timer is turned on which restarts the cycle after a preselected amount of time. When the system is restarted by the shutdown timer, a pump-up timer is turned on which is adjusted to allow for a desired pump-up time. As the pump-up timer is allowing the system to recycle, the integration timer is reset and the recycling is completed if the requirements of the integration timer are met. Otherwise, the unit is shut down again and the system recycled. A variable electronic scaler is connected to the output of the integration timer which monitors the output signals from the integrator timer. After the preset number of times the integration timer produces a signal, unless reset by a normal cycle, the scaler turns off the whole system. It can then be restarted manually.
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