ABB ControlMaster CM30 User Manual

Also see for ControlMaster CM30: Communications supplement User guide User guide Manual Manual

Contents

ABB ControlMaster CM30 User Manual Manual pdf 66 page image

ControlMaster CM30, CM50 and CMF310Universal process controllers, 1/ 4, 1/ 2 DIN and fieldmount 7 Advanced Level64 IM/CM/ED–EN Rev. X7.6.4 Retort FunctionThe Retort function ensures safe operation of retort vessels under fault conditions. If the heat source failsduring a soak segment, the process variable will inevitably fall. When the process variable falls below theholdback hysteresis value the program is put on HOLD (as for normal operation). The set point then followsthe process variable as it continues to fall (Retort Hold). Set Point = Process Variable + Hysteresis valueUpon recovery of the heat source, the process is controlled at the new set point value. When the processvariable reaches the set point it is then ramped back to the initial soak value at the rate of the previous ramp(Retort Ramp). When the soak level is reached the program is released from its hold state and the segmentis either completed or repeated from the beginning, depending on the retort mode selected.The retort mode is selected in the Ramp / Soak Profile page.Note. For the retort function to operate, either LO or HI-LO hysteresis must be applied to the soaksegments.1 The program is put on HOLD when the process variable falls below the holdback hysteresis.2 The setpoint follows the process variable as it continues to fall. (SP = PV + hysteresis).The set point 'tracks the lowest value of the process variable.3 When the process variable reaches the set point, the set point is ramped back to thesoak level at the rate of the previous ramp.4 Upon reaching the soak level, 'HOLD' is released and the segment is completed or repeated.Fig. 7.4 Retort Function1 234Program on holdSeg. 1 Seg. 2Recovery of heat sourceFailure of heat sourceSet pointProcess variableHysteresis applied tosoak segment