Closed Loop Drive System; Programming Of Torque Limit And Stop - Danfoss VLT AutomationDrive FC 300 Design Manual

Application Examples

8.1.1 Closed Loop Drive System

A drive system consist usually of more elements such as:
•
Motor
•
Add
(Gearbox)
(Mechanical Brake)
•
FC 302
•
Encoder as feed-back system
•
Brake resistor for dynamic braking
•
Transmission
•
Load
Applications demanding mechanical brake control will
usually need a brake resistor.
8 8
Encoder Mech. brake
Illustration 8.5 Basic Set-up for FC 302 Closed Loop Speed
Control
8.1.2 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.
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VLT
Brake resistor
Transmission
Motor
Gearbox
MG33BE02 - VLT
®
AutomationDrive FC 300 Design Guide, 0.25-75 kW
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
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 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 Start [8]
•
Quickstop via terminal 27
5-12 Terminal 27 Digital Input Coasting Stop,
Inverse [2]
•
Terminal 29 Output
5-02 Terminal 29 Mode Terminal 29 Mode Output
[1]
5-31 Terminal 29 Digital Output Torque Limit &
Stop [27]
•
Relay output [0] (Relay 1)
5-40 Function Relay Mechanical Brake Control [32]
Load
®
is a registered Danfoss trademark