Danfoss VLT AQUA Drive FC 202 Design Manual

Also see for VLT AQUA Drive FC 202: Service guide Installation guide Installation guide Operating guide Installation guide

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Danfoss VLT AQUA Drive FC 202 Design Manual Manual pdf 31 page image

5.5.1.1 Pump Staging with Lead PumpAlternationWith lead pump alternation enabled, a maximum of 2pumps are controlled. At an alternation command, the PIDstops, the lead pump ramps to minimum frequency (fmin)and, after a delay, it ramps to maximum frequency (fmax).When the speed of the lead pump reaches the destagingfrequency, the fixed-speed pump is cut out (destaged). Thelead pump continues to ramp up and then ramps down toa stop and the 2 relays are cut out.TimeTimeAC line operationDestaging freq.Alternationcommand/PID stopsStaging freq. AC line operationPID contr.starts130BA364.105sf maxf maxf minFigure 5.11 Lead Pump AlternationAfter a time delay, the relay for the fixed-speed pump cutsin (staged) and this pump becomes the new lead pump.The new lead pump ramps up to maximum speed andthen down to minimum speed. When ramping down andreaching the staging frequency, the old lead pump is nowcut in (staged) on the mains as the new fixed-speed pump.If the lead pump has been running at minimum frequency(fmin) for a programmed amount of time, with a fixed-speed pump running, the lead pump contributes little tothe system. When the programmed value of the timerexpires, the lead pump is removed, avoiding water heatingproblems.5.5.1.2 System Status and OperationIf the lead pump goes into sleep mode, the function isshown on the LCP. It is possible to alternate the lead pumpon a sleep mode condition.When the cascade controller is enabled, the LCP shows theoperation status for each pump and the cascade controller.Information shown includes:• Pump status is a readout of the status for therelays assigned to each pump. The display showspumps that are disabled, off, running on thedrive, or running on the mains/motor starter.• Cascade status is a readout of the status for thecascade controller. The display shows thefollowing:- Cascade controller is disabled.- All pumps are off.- An emergency has stopped all pumps.- All pumps are running.- Fixed-speed pumps are being staged/destaged.- Lead pump alternation is occurring.• Destage at no-flow ensures that all fixed-speedpumps are stopped individually until the no-flowstatus disappears.5.6 Deragging OverviewThe purpose of the deragging feature is to free the pumpblade of debris in waste-water applications so that thepump operates normally.A deragging event is defined as the time when the drivestarts to derag to when the deragging finishes. When aderag is started, the drive ramps first to a stop and thenan off delay expires before the first cycle begins.0 Hz / RPMDerag Off Delay:Par. 29 -15+/- DeragSpeed:Par.: 29 -13Par.: 29 -14Deragging Run Time : Par . 29-12SpeedDeragfunctionactivated1 CycleNumber of Cycles : Par . 29 -10130BC369.10Figure 5.12 Derag FunctionProduct Features Design GuideMG22B222 Danfoss A/S © 01/2018 All rights reserved. 295 5