Closed Loop Drive System; Programming Of Torque Limit And Stop - Danfoss VLT AutomationDrive FC 301 Design Manual

Application Examples

10.1.1 Closed Loop Drive System

A frequency converter system consist usually of more
elements such as
•
Motor
•
Gearbox
•
Mechanical Brake
•
Frequency converter
•
Encoder as feed-back system
•
Brake resistor for dynamic braking
•
Transmission
•
Load
Applications demanding mechanical brake control usually
need a brake resistor.
Motor
Encoder Mech. brake
Illustration 10.5 Example of FC 302 Closed Loop Speed Control
®
VLT AutomationDrive FC 301/FC 302 Design Guide, 0.25-75 kW
Brake resistor
Transmission
Gearbox
Load
MG33BF02 - Rev. 2013-12-20
10.1.2 Programming of Torque Limit and
Stop
In applications with an external electro-mechanical brake,
such as hoisting applications, it is possible to stop the
frequency converter via a 'standard' stop command and
simultaneously activate the external electro-mechanical
brake.
The example given below illustrates the programming of
frequency converter connections.
The external brake can be connected to relay 1 or 2.
Program terminal 27 to [2] Coast, inverse or [3] Coast and
Reset, inverse, and program terminal 29 to [1] Terminal
mode 29 Output and [27] Torque limit & stop.
Description
If a stop command is active via terminal 18 and the
frequency converter is not at the torque limit, the motor
ramps down to 0 Hz.
If the frequency converter is at the torque limit and a stop
command is activated, terminal 29 Output (programmed to
[27] Torque limit and stop) 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 the frequency converter itself cannot handle the
required torque (i.e. due to excessive overload).
•
Start/stop via terminal 18
5-10 Terminal 18 Digital Input, [8] Start
•
Quickstop via terminal 27
5-12 Terminal 27 Digital Input, [2] Coasting Stop,
Inverse
•
Terminal 29 Output
5-02 Terminal 29 Mode, [1] Terminal 29 Mode
Output
5-31 Terminal 29 Digital Output, [27] Torque Limit &
Stop
•
Relay output [0] (Relay 1)
5-40 Function Relay, [32] Mechanical Brake Control
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