Danfoss VLT Series Operating Instructions Manual

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Danfoss VLT Series Operating Instructions Manual Manual pdf 21 page image

1.5.5 Staging / De-staging of fixed speed pumps based on Pressure FeedbackFixed speed pumps are staged based on a drop in system pressure. And are de-staged based on an increases in system pressure.Since it is undesirable to have pumps turning on and off rapidly, an acceptable range of system pressure needs to be defined along with a period of timethe pressure is allowed to be outside of this band before staging or de-staging occurs. These values are set through parameters 27-20 “Normal OperatingRange” 27-23 “Staging Delay” and 27-24 “De-staging Delay”.These parameters are installation dependent and should be set to meet the requirements of the system.Automatic stage / de-stage thresholdThe speed of the variable speed pump at the point of staging or de-staging is defined by stage threshold or a de-stage threshold. These settings areusable in order to secure as minimum over or undershoot in the pressure at staging or de-staging.Compared to the basic cascade built in the drive, these settings can be auto tuned in extended and advanced cascade options MCO101 and MCO102.If enabled the auto tune of staging and de-staging threshold will monitor the feedback in the point of staging or de-staging and fine adjust the settingsevery time a staging takes place in order to keep the system optimized over time taking into account wear and tear of the pumps.New parameter descriptions:Number Display name Range Default27-30 Auto Tune Staging Speeds {Disabled [0], Enabled [1]} Enabled [1]27-40 Auto Tune Staging Settings {Disabled [0], Enabled [1]} Enabled [1]1.6 ControlOnce the Cascade controller has been configured it can be enabled or disabled through parameter 27-10 “Cascade Controller”. To start the cascadecontroller the Master Drive needs to be started as a normal Drive through the LCP or through field buss communications. It will then attempt to controlthe system pressure by varying the speed of the FC and by staging on and off pumps as needed.Two stop functions are provided by the cascade controller. One function quickly stops the system. The other stages off pumps in a sequence, allowingfor a pressure controlled stop. For the VLT AQUA Drive equipped with Safe Stop, Terminal 37 will turn off all relays and coast the Master drive. If any ofthe digital inputs are set to [8] “Start” and the corresponding terminal is used to control the starting and stopping of the drive then setting the terminalto 0 volts will turn off all relays and coast the Master drive. Pressing the OFF button on the LCP will cause a sequenced de-staging of all of the runningpumps.1.7 Cascade Controller Features1.7.1 Pump Status and ControlThe 27-0* group of parameters provides a convenient place to check on the status of the Cascade Controller and to control individual pumps. In thisparameter group it is possible to select a specific pump to view the current status, the current running hours, and the total lifetime hours. From the samelocation an individual pump can be manually controlled for maintenance purposes.The parameter group is organized as follows:Parameter Pump 1 Pump 2 Pump 3 Pump …27-01 Status On Drive Ready Offline-off27-02 Control No Operation No Operation No Operation27-03 Current Hrs 650 667 40027-04 Lifetime Hrs. 52673 29345 30102Navigate to the 27-0* group on the LCP.Use right and left arrows on the LCP to select the pump. Use up and down arrows on the LCP to select the parameter.VLT® Operating Instructions1 Extended and Advanced Cascade ControllerOptionMI.38.C3.02 - VLT® is a registered Danfoss trademark 211