Danfoss VLT AutomationDrive FC 302 Installation Manual

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Danfoss VLT AutomationDrive FC 302 Installation Manual Manual pdf 49 page image

4.9 Additional Connections4.9.1 Serial CommunicationRS-485 is a 2-wire bus interface compatible with multi-dropnetwork topology, i.e., nodes can be connected as a bus,or via drop cables from a common trunk line. A total of 32nodes can be connected to one network segment.Repeaters divide networkNOTICE!Each repeater functions as a node within the segment inwhich it is installed. Each node connected within a givennetwork must have a unique node address across allsegments.Terminate each segment at both ends using either thetermination switch (S801) of the adjustable frequencydrives or a biased termination resistor network. Always useshielded twisted pair (STP) cable for bus cabling, andalways follow good common installation practice.Low-impedance ground connection of the shield at everynode is important, including at high frequencies. Thus,connect a large surface of the shield to ground, forexample, with a cable clamp or a conductive cableconnector. It may be necessary to apply potential-equalizing cables to maintain the same ground potentialthroughout the network - particularly in installations withlong cables.To prevent impedance mismatch, always use the sametype of cable throughout the entire network. Whenconnecting a motor to the adjustable frequency drives,always use shielded motor cable.Cable Shielded twisted pair (STP)Impedance 120 ΩCable length Max. 4000 ft [1200 m] (including drop lines)Max. 1,650 ft [500 m] station-to-stationTable 4.10 Cable Recommendations4.9.2 Mechanical Brake ControlIn hoisting/lowering applications, it is necessary to beable to control an electro-mechanical brake:• Control the brake using any relay output ordigital output (terminal 27 or 29).• Keep the output closed (voltage-free) as long asthe adjustable frequency drive is unable to‘support’ the motor, e.g., due to the load beingtoo heavy.• Select [32] Mechanical brake control in parametergroup 5-4* Relays for applications with an electro-mechanical brake.• The brake is released when the motor currentexceeds the preset value inparameter 2-20 Release Brake Current.• The brake engages when the output frequency isless than the frequency set inparameter 2-21 Activate Brake Speed [RPM] orparameter 2-22 Activate Brake Speed [Hz], only ifthe adjustable frequency drive completes a stopcommand.If the adjustable frequency drive is in alarm mode or in anovervoltage situation, the mechanical brake immediatelycuts in.4.9.3 Parallel Connection of MotorsThe adjustable frequency drive can control several motorsconnected in parallel. The total current consumption of themotors must not exceed the rated output current IM,N forthe adjustable frequency drive.Electrical Installation Installation ManualMG37A322 Danfoss A/S © Rev. 04/2015 All rights reserved. 474 4