9.1.6 Closed-loop Drive SystemA drive system consist usually of more elements such as:• Motor• Add(Gearbox)(Mechanical Brake)• AutomationDrive FC 302 AutomationDrive• Encoder as feedback system• Brake resistor for dynamic braking• Transmission• LoadApplications demanding mechanical brake control will usually need abrake resistor.Figure 9.1: Basic Set-up for AutomationDrive FC 302Closed-loop Speed Control9.1.7 Programming of Torque Limit and StopIn applications with an external electro-mechanical brake, such as hoisting applications, it is possible to stop the adjustable frequency drive via a 'standard'stop command and simultaneously activate the external electro-mechanical brake.The example given below illustrates the programming of adjustable frequency drive connections.The external brake can be connected to relay 1 or 2, see paragraphControl of Mechanical Brake. Program terminal 27 to Coast, inverse [2] or Coast andReset, inverse [3], and program terminal 29 to Terminal mode 29 Output [1] and Torque limit & stop [27].Description:If a stop command is active via terminal 18 and the adjustable frequency drive is not at the torque limit, the motor ramps down to 0 Hz.If the adjustable frequency drive is at the torque limit and a stop command is activated, terminal 29 Output (programmed to Torque limit and stop [27])is activated. The signal to terminal 27 changes from 'logic 1' to 'logic 0', and the motor starts to coast, thereby ensuring that the hoist stops even if theadjustable frequency drive itself cannot handle the required torque (i.e., due to excessive overload).- Start/stop via terminal 18par. 5-10Terminal 18 Digital Input Start [8]- Quickstop via terminal 27par. 5-12Terminal 27 Digital Input Coasting Stop, Inverse [2]- Terminal 29 Outputpar. 5-02Terminal 29 Mode Terminal 29 Mode Output [1]par. 5-31Terminal 29 digital Output Torque Limit & Stop [27]- Relay output [0] (Relay 1)par. 5-40Function Relay Mechanical Brake Control [32]FC 300 Design Guide 9 Application ExamplesMG.33.BC.22 - VLT® is a registered Danfoss trademark 9-39
