Danfoss VLT Decentral Drive FCD 302 Design Manual

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Danfoss VLT Decentral Drive FCD 302 Design Manual Manual pdf 67 page image

4.8 Mechanical BrakeFor hoisting applications, it is necessary to be able tocontrol an electro-magnetic brake. For controlling thebrake, a relay output (relay1 or relay2) or a programmeddigital output (terminal 27 or 29) is required. Normally, thisoutput must be closed for as long as the frequencyconverter is unable to ’hold’ the motor, for example,because of excess load. For applications with an electro-magnetic brake, select [32] mechanical brake control in oneof the following parameters:5-40 Function Relay (Array parameter),5-30 Terminal 27 Digital Output, or5-31 Terminal 29 Digital OutputWhen [32] mechanical brake control is selected, themechanical brake relay stays closed during start until theoutput current is above a preset level. Select the presetlevel in 2-20 Release Brake Current. During stop, themechanical brake closes when the speed is below the levelselected in 2-21 Activate Brake Speed [RPM]. When thefrequency converter is brought into an alarm condition(that is, an over-voltage situation), or during safe stop, themechanical brake immediately cuts in.Illustration 4.22 Mechanical Brake Control for Hoisting ApplicationsIn hoisting/lowering applications, it must be possible tocontrol an electromechanical brake.Step-by-step Description• To control the mechanical brake, use any relayoutput, digital output (terminal 27 or 29) or solid-state brake voltage output (terminals 122 - 123).Use a suitable contactor when required.• Ensure that the output is switched off as long asthe frequency converter is unable to drive themotor. For example, due to the load being tooheavy, or when the motor is not yet mounted.• Select [32] mechanical brake control in parametergroup5-4* (or in parameter group 5-3*) beforeconnecting the mechanical brake.• The brake is released when the motor currentexceeds the preset value in 2-20 Release BrakeCurrent.• The brake is engaged when the output frequencyis lower than a preset limit. Set the limit in2-21 Activate Brake Speed [RPM] or 2-22 ActivateBrake Speed [Hz] and only if the frequencyconverter carries out a stop command.Application Examples VLT® Decentral Drive FCD 30266 MG04H102 - VLT® is a registered Danfoss trademark44