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Application Examples
17.13 Closed-loop Drive System
A closed-loop drive system usually consists of the
following:
•
Motor
•
Frequency converter
•
Encoder as feedback system
•
Mechanical brake
•
Brake resistor for dynamic braking
•
Transmission
•
Gear box
•
Load
Applications demanding mechanical brake control typically
needs a brake resistor.
Encoder
Illustration 17.7 Basic Set-up for FC 302 Closed-loop Speed
Control
17.14 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.
Illustration 17.8 shows the programming of these frequency
converter connections.
If a stop command is active via terminal 18 and the
17
17
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, the system activates terminal 29
Output (programmed to [27] Torque limit & stop). The signal
to terminal 27 changes from logic 1 to logic 0 and the
motor starts to coast, ensuring that the hoist stops even if
the frequency converter itself cannot handle the required
torque, for example due to excessive overload.
158
®
VLT
Brake resistor
Transmission
Motor
Gearbox
Mech. brake
Load
Danfoss A/S © 6/2016 All rights reserved.
Parallel Drive Modules
To program the stop and torque limit, connect to the
following terminals:
•
Start/stop via terminal 18
parameter 5-10 Terminal 18 Digital Input [8] Start
•
Quick stop via terminal 27
parameter 5-12 Terminal 27 Digital Input [2]
Coasting Stop, Inverse
•
Terminal 29 Output
parameter 5-02 Terminal 29 Mode [1] Terminal 29
Mode Output
parameter 5-31 Terminal 29 Digital Output [27]
Torque limit & stop
•
Relay output [0] (Relay 1)
parameter 5-40 Function Relay [32] Mechanical
Brake Control
12
13
External
24 V DC
Illustration 17.8 Stop and Torque Limit Terminal Connections
18
19
27
29
32
33
20
37
Start
I
0.1 Amp
-
max
+
P 5-40 [0] [32]
Mechanical brake
connection
MG37N102
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