Danfoss VT2800 Series Design Manual

Contents

VLT ® 2800 Series■ Load and Motor■ ConfigurationSelection of configuration and torque characteristicshas an effect on which parameters can be seen in thedisplay. If Open loop [0] is selected, all parametersrelating to PID regulation will be filtered out. Thismeans that the user only sees the parameters thatare relevant for a given application.100 Configuration(CONFIGURATION)Value:✭Speed control, open loop(SPEED OPEN LOOP) [0]Speed control, closed loop(SPEED CLOSED LOOP) [1]Process control, closed loop(PROCESS CLOSED LOOP) [3]Function:This parameter is used to select the configurationto which the frequency converter is to be adapted.This makes adaptation to a given applicationsimple, since the parameters not used in a givenconfiguration are hidden (not active).Description of choice:If Speed control, open loop [0] is selected, normalspeed control is obtained (without feedbacksignal) with automatic load and slip compensationto ensure a constant speed at varying loads.Compensations are active, but may be disabled inparameter 134 Load compensation and parameter136 Slip compensation as required.If Speed control, closed loop [1] is selected, betterspeed accuracy is obtained. A feedback signal mustbe added, and the PID regulator must be set inparameter group 400 Special functions.If Process control, closed loop [3] is selected, theinternal process regulator is activated to enable precisecontrol of a process in relation to a given processsignal. The process signal can be set to the relevantprocess unit or as a percentage. A feedback signalmust be added from the process and the processregulator must be set in parameter group 400 Specialfunctions. Process closed loop is not active if aDeviceNet card is mounted and Instance 20/70 or21/71 is chosen in parameter 904 Instance types.101 Torque characteristic(TORQUE CHARACT)Value:✭Constant torque(CONSTANT TORQUE) [1]Variable torque low(TORQUE: LOW) [2]Variable torque medium(TORQUE: MED) [3]Variable torque high(TORQUE: HIGH) [4]Variable torque low with CT start(VT LOW CT START) [5]Variable torque medium with CT start(VT MED CT START) [6]Variable torque high with CT start(VT HIGH CT START) [7]Special motor mode(SPECIAL MOTOR MODE) [8]CT = Constant torqueFunction:This parameter enables a choice of principlefor adaptation of the U/f ratio of the frequencyconverter to the torque characteristic of theload. See par. 135 U/f ratio.Description of choice:If Constant torque [1] is selected, a load-dependent U/fcharacteristic is obtained, in which output voltage andoutput frequency are increased at increasing loads inorder to maintain constant magnetization of the motor.Select Variable torque low [2], Variable torquemedium [3] or Variable torque high [4], if the loadis square (centrifugal pumps, fans).Variable torque - low with CT start [5], - medium withCT start [6] or high with CT start [7], are selected ifyou need a greater breakaway torque than can beachieved with the three first characteristics.NB!:Load and slip compensation are notactive if variable torque or special motormode have been selected.✭ = factory setting. () = display text [] = value for use in communication via serial communication portMG.28.E9.02 - VLT is a registered Danfoss trademark68