User Guide - Eurotherm Ltda

nanodac RECORDER/CONTROLLER: USER GUIDEB2.5.2 Setpoint LimitsThe setpoint generator provides limits for each of the setpoint sources as well as an overall set of limits forthe loop. These are summarised in figure 2.5.2, below.MaxDispRangeHigh+SpanSPHigh LimitSP TrimHighRemoteSP1SP2TargetSPWorkingSPLoopAlmsetpointsSP TrimSPLow LimitSP TrimLowMinDispRangeLow-SpanFigure 2.5.2 Setpoint Limits‘Range High’ and ‘Range Low’ provide the range information for the control loop. They are used in controlcalculations to generate proportional bands. Span = Range High – Range Low.B2.5.3 Setpoint Rate LimitThis symmetrical rate limiter allows the rate of change of setpoint to be controlled, preventing step changesin the setpoint. The limit is applied to the working setpoint which includes setpoint trim.Rate limiting is enabled using the ‘Rate’ parameter. If this is set to ‘0’ then any change made to the setpointwill be effective immediately. If it is set to any other value, then a change in the setpoint will be have ratelimiting applied at the value set, in units per minute. Rate limit applies to SP1, SP2 and Remote SP.When rate limit is active ‘Rate Done’ displays ‘No’. When the setpoint has been reached the value changesto ‘Yes’.When ‘Rate’ is set to a value (other than ‘Off’) an additional parameter ‘SP Rate Disable’ is displayed whichallows the setpoint rate limit to be turned off and on without the need to adjust the ‘Rate’ parameter betweenOff and a working value.If the PV is in sensor break, the rate limit is suspended and the working setpoint takes the value of 0. Onsensor break being released the working setpoint goes from 0 to the selected setpoint value at the rate limit.Appendix BPage 318HA030554Issue 7 Nov 12