ABB C1900 Series Operating Manual

Also see for C1900 Series: Installation guide User guide Installation guide Operating instructions Operating guide

ABB C1900 Series Operating Manual Manual pdf 35 page image

33MrESEtOFFPAGEContrLc 50.0dErIVAPPbCrSOUrt–bANdt–bANdOFFHYSc 100.0c 0.00.1OFF3.00.1100.00.0100.00.025.00.0999.050.01.010.025.0IntegralOffDerivativeOff5 CONTROL OPERATION…5.10.1 Control Page (Heat/Cool Control)Manual Reset (cool output)Set the required proportional band offset, between 0.0 and 100.0% of theengineering range span in 0.1% increments.Derivative Action TimeSet the required time between 0.1 and 999.9 in 0.1 second increments (999.9seconds = 16.67 minutes). 'OFF' is selected below 0.1.Approach BandSet the required value between 0.1 and 3.0 in 0.1 increments. (Set 1.0 initially).Crossover Output ValueSet the required value between 0.0 and 100.0% of the PID output, in 0.1%increments – see Section 5.10.2.Transition BandwidthSet the required value between 0.0 and 100.0% of the PID output, in 0.1%increments – see Section 5.10.3.Output Off Hysteresis BandSet the required value which prevents oscillation of control changes, between 0.0 and25.0% of the PID output, in 0.1% increments.5.10.2 Calculating the Crossover Value – Fig. 5.18The crossover value is calculated from the expression:100Gh/Gc + 1Crossover Value =Where Gh/Gc is the ratio of the two output driver gains.The most common method for determining the Gh/Gc term is byusing 'nameplate' values from the heat/cool device(s).If a heat/cool application can produce a maximum of 1.5kW andabsorb 0.75kW:1.50.75Output Gain Ratio = = 21002 + 1Crossover Value = = 33.3%5.10.3 Calculating the TransitionBandwidth Value – Fig 5.18The Transition Bandwidth is the percentage difference of theproportional band settings.Example – if the proportional band settings for the heat output is20% and for the cool output is 25%:25 – 2025 x 100Transition Bandwidth (%) =Transition Bandwidth = 20%If the proportional band settings for both outputs are equal, thebandwidth is 0%. As a general rule, the Transition Bandwidthshould not exceed 30%.