Control of chokes

摘要

A well choke control apparatus comprising means for producing a first electrical signal indicative of a required position of the choke and means for deriving a second electrical signal indicative of the actual position of the choke. A comparator is arranged to be fed with the first and second electrical signals and to control actuation of the choke in the required direction to equalize said electrical signals. A number of override control arrangements may be provided to ensure that the choke is not opened or closed beyond predetermined safe limits and the main control comparator is self checking.