FC 300 Design GuideHow to Install" Control of Mechanical BrakeControl an electromechanical brake in hoisting/lowering applications.ï Control the brake using any relay output or digital output (terminal 27 or 29).ï Keep the output closed (voltage-free) as long as the adjustable frequency drive is unable to"support" the motor, for example due to the load being too heavy.ï Select Mechanical brake control [32] in par. 5-4* for applications with an electromechanical brake.ï The brake is released when the motor current exceeds the preset value in par. 2-20.ï The brake is engaged when the output frequency is less than the frequency set in par. 2-21 or2-22, and only if the adjustable frequency drive carries out a stop command.If the adjustable frequency drive is in alarm mode or in an overvoltage situation, themechanical brake immediately cuts in." Parallel Connection of MotorsThe adjustable frequency drive can controlseveral motors connected in parallel. The totalcurrent consumption of the motors must notexceed the rated output current I INV for theadjustable frequency drive.This is only recommended when VVC plus isselected in par. 1-01.Problems may arise at start and at low RPM values if motor sizes are widely different because small motorsírelatively high ohmic resistance in the stator requires a higher voltage at start and to operate at low RPM values.The electronic thermal relay (ETR) of the adjustable frequency drive cannot be used as motor protection forthe individual motor of systems with parallel-connected motors. Provide further motor protection by e.g.thermistors in each motor or individual thermal relays. (Circuit breakers are not suitable as protection).NOTEWhen motors are connected in parallel, par. 1-02 Automatic motor adaptation (AMA) cannot beused, and par. 1-01 Torque characteristics must be set to Special motor characteristics.103MG.33.B3.22 - VLT is a registered Danfoss trademark
