Patent ID: 6023222
Filing Date: 2000-02-08
Classification: G05B,G05D

Abstract:
A method for monitoring a plurality of control loops, with each control loop comprising a control sensor, a controller, and a controlled system, and with all loops having identical setpoint values of the controlled quantity; said method comprising the following steps:a) during an initial phasea1) the actual value of the controlled quantity in each controlled system is measured by an adjustment sensor and is controlled by said controller to said common setpoint;a2) a first mean value is derived from the values of the controlled quantity as measured by said adjustment sensor at the various controlled systems, and this first mean value is for each control point compared with the controlled quantity as measured there by said adjustment sensor;a3) the therewith determined errors of the actual value at the individual control points are compared with a predetermined limit;a4) during the subsequent calculation of an improved second mean value, those control points with a control error exceeding said limit remain unused;a5) the actual value of the controlled quantity in each of the control systems is controlled to said common setpoint by adding a correction value to the actual value as measured by said control sensor;a6) after reaching a stationary operating condition, a regulation ratio of each controller is determined in the form of the ratio of the actual value of the controlled quantity divided by a predetermined maximum value of said controlled quantity; anda7) for each control loop said regulation ratio is stored in a memory;b) for additionally monitoring the operation of said control loops during a subsequent operating phaseb1) for each control loop the actual regulation ratio is compared with the value of said stored regulation ratio; andb2) an alarm signal is generated if an actual regulation ratio deviates from said stored value by more than a predetermined amount.