Pneumatic controller with auto and manual facility - uses third line in automatic mode controlling switch in regulator connected to feedback element

摘要

The modified pneumatic controller with automatic and manual operation has less switching elements and connecting lines than previous types. One line connects the desired value adjustment (Pw) in the control unit with the comparator in the regulator (V). A second line (L2) connects the manipulated variable via a switch (HRS) to one of two indicators of a gauge (M) in either the automatic or manual positions. In the automatic position of the switch, a third line (L3) controls a switch in the regulator (S5) so that the output of the control amplifier (RV) is connected to the controller output and to the feedback element (RF). In the manual position, the amplifier is isolated, the feedback element shunted and the manual control variable switched to the comparator position.