3.5 Additional Connections
3.5.1 Parallel Connection of Motors
The frequency converter can control several parallel-connected motors. The
total current consumption of the motors must not exceed the rated output
current I
M,N
for the frequency converter.
NB!
Installations with cables connected in a common joint as in the illustration
below, is only recommended for short cable lengths.
NB!
When motors are connected in parallel, par. P-04 Auto Tune cannot be used.
NB!
The electronic thermal overload of the frequency converter cannot be used
as motor protection for the individual motor in systems with parallel-con-
nected motors. Provide further motor protection by e.g. thermistors in each
motor or individual thermal relays (circuit breakers are not suitable as pro-
tection).
Problems may arise at start and at low RPM values if motor sizes are widely different because small motors' relatively high ohmic resistance in the stator calls for
a higher voltage at start and at low RPM values.
3.5.2 Motor Thermal Protection
The electronic thermal overload in the frequency converter has received UL-approval for single motor protection, when par. F-10 Electronic Overload is set for
Elec. OL Trip and par. P-03 Motor Current is set to the rated motor current (see motor name plate).
AF-600 FP High Power Operating Instructions
36
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