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•
Problems can occur at start and at low RPM if motor sizes are widely different because the relatively high ohmic
resistance in the stator of a small motor demands a higher voltage at start and at low RPM.
•
The electronic thermal relay (ETR) of the frequency converter cannot be used as motor protection. Provide further
motor protection by including thermistors in each motor winding or individual thermal relays.
•
When motors are connected in parallel,
parameter 1-02 Flux Motor Feedback Source
cannot be used, and
parameter 1-01 Motor Control Principle
must be set to [0]
U/f
.
130BB838.12
a
b
c
d
e
f
A
Installations with cables connected in a common joint as shown in A and B are only recommended for short cable lengths.
B
Be aware of the maximum motor cable length specified in
chapter 6.10 Cable Specifications
C
The total motor cable length specified in
chapter 6.10 Cable Specifications
is valid as long as the parallel cables are kept short less
than 10 m (32 ft) each. See example 1.
D
Consider voltage drop across the motor cables. See example 1.
E
Consider voltage drop across the motor cables. See example 2.
F
The total motor cable length specified in
chapter 6.10 Cable Specifications
is valid as long as the parallel cables are kept less than 10
m (32 ft) each. See example 2.
Illustration 10.12 Different Parallel Connections of Motors
Motor
VLT
®
Parallel Drive Modules
114
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MG37N102
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Summary of Contents for VLT 380-500 V
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