Static Control System
an automatic control system in which the error in the steady state is usually not equal to zero and depends on the load on the controlled system.
Figure 1 shows a block diagram of a single-loop static control system consisting of a controlled system and a control unit. The latter consists of a measuring transducer, automatic controller, and actuating mechanism. The control action x2 (t) and external disturbances f(t) act on the controlled system. The controlled variable x(t) of the controlled system is converted by the measuring transducer into the signal x*(t); the signal is fed to the automatic controller, where it is compared with the given value of the control action g(t) to form the error signal μ(t) = g(t)−x*(t). Subsequently, the dependence of μ(t) on the control variable x1(t) of the automatic controller is obtained to form the control curve. For a proportional position action controller, x1 = kt, μ where kt is the coefficient of transmission (amplification) of the automatic controller.
As a rule, static controllers are relatively simple and economical and have quick response times. These characteristics make them suitable for use in automatic control systems for industrial installations. Figure 2 shows a very simple static control system for regulating the level of a liquid in a vessel. If there is an increase in the loss of liquid, the liquid level in the vessel is reduced, the position of the float is altered, and the gate in the valve rises, increasing the inflow of liquid. The steady state is achieved when the loss of liquid is equal to the inflow, which corresponds to some level different from the original level.
REFERENCES
See references under AUTOMATIC CONTROL.A. V. KOCHEROV