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

Application Examples

8.13 Closed Loop Drive System

A closed loop drive system usually consists of the
following:
•
Motor
•
Add
(Gearbox)
(Mechanical Brake)
•
FC 302
•
Encoder as feed-back system
•
Brake resistor for dynamic braking
•
Transmission
•
Load
Applications demanding mechanical brake control typically
needs a brake resistor.
8 8
Encoder
Illustration 8.7 Basic Set-Up for FC 302 Closed Loop Speed
Control

8.14 Stop and Torque Limit

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
these frequency converter connections. The external brake
can be connected to relay 1 or 2 (See 3.9 Mechanical Brake
Control). 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.
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.
224
®
VLT
Brake resistor
Transmission
Motor Gearbox
Mech. brake Load
AutomationDrive FC 300 Design Guide 90-1200 kW
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, for example due to excessive overload.
To program the stop and torque limit, connect to the
following terminals:
•
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]
12 13
External
24 VDC
Illustration 8.8 Stop and Torque Limit Terminal Connections
MG34S202 - Rev. 2013-08-19
18 19 27 29 32 33 20 37
Start
I max 0.1 Amp
-
+
P 5-40 [0] [32]
Mechanical Brake
Connection