Danfoss VLT 2010 Manual

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Danfoss VLT 2010 Manual Manual pdf 41 page image

42Appendix; PI RegulationParameter 120:Controls the bandwidth of the output from PID controller.Set at 100%.Parameter 121:Controls the gain of the system. For most fan and pumpsystems it should not be higher than 0.9. If set to highervalues the system may become unstable.• Centrifugal fans - between 0.1 - 0.6• Centrifugal pumps - between 0.3 - 0.8Parameter 122:Improves the final accuracy by integrating out the error.• Centrifugal fans - between 10-12 seconds• Centrifugal pumps - between 3-8 secondsParameter 123:Differential time is not used in pump and fan systems.Set to Off.Parameter 124:If the feedback signal is fluctuating it can be dampenedwith a time constant. This can occur on pump systemswhere the pipe can be shut off quickly and cause astanding wave of water.Set initially to 0 seconds.Parameter 125:Leave at the default value of 100% unless thefollowing conditions occur.• If the feedback signal does not match the standardanalog signal choices in parameter 412 & 413 a valuemust be programmed which scales the feedback signalto a standard analog value.• When using min. speed, parameter 201, it must beensured that the min. speed % value is not greater thanthe set-point % value, otherwise the min. speed willover-ride the set-point.(See example on page 43.)The following instructions will enable quick and easy set-up of the PI regulation and associated parametersettings. Detailed information about each parameter canbe found in the parameter section of this manual.Parameter 100:Set the load type. There are several choices in eachgroup but variable torque medium or variable torquemedium with AEO will suit most pumps or fans.Parameter 101:Select closed loop operation.Parameter 114:Choose the type of feedback signal the transmitter isusing. The default value is current as it is the mostwidely used signal type.Parameter 115 & 116:Are used to scale a display read-out which is proportionalto the feedback transmitter signal. The value is displayedonly if feedback has been selected in display mode. Toget to display mode from any other mode press MENU &DATA keys simultaneously.If a transmitter has a range of 0-5 bar, 0 can be set inparameter 115 and 5 in parameter 116. In parameter 117the unit bar can be programmed.The default values are 0 & 100, to display 0-100%.Parameter 117:Choose the unit of measurement for scaling thefeedback signal of the transmitter set in parameter 115 &116. The default value is %.Parameter 119:The feed forward factor allows a part of the set-pointsignal to by-pass the PID regulator. This gives fasterresponse when starting up a system where theintegration time (parameter 122) is very long, and thesystem error is small.Set at 0%. Only add 5% at a time, and only if the systemtakes a long time to start up. The drawing shows theinfluence of the feed forward.FeedforwardProcessFBfactorPID Me+–+Feedback signalSetpointorReference(RampsP: 215, 216)(P: 119)Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com