Danfoss FC 300 Design Manual page 176

8 Electrical Installation
NB!
When motors are connected in parallel, par. 1-02
Motor Feedback Source
par. 1-01
motor characteristics (U/f)
8
Frame Size Power Size
A1, A2, A5 0.37-0.75 kW
A2, A5 1.1-1.5 kW
A2, A5 2.2-4 kW
A3, A5 5.5-7.5 kW
B1, B2, B3, B4, 11-75 kW
C1, C2, C3, C4
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.
The electronic thermal relay (ETR) of the frequency converter cannot be used as motor protection for the individual motor of systems with parallel-
connected motors. Provide further motor protection by e.g. thermistors in each motor or individual thermal relays. (Circuit breakers are not suitable as
protection).
176
cannot be used, and
Motor Control Principle
must be set to
.
Voltage [V]
400
500
400
500
400
500
400
500
400
500
MG.33.BC.02 - VLT
Flux
Special
1 cable [m] 2 cables [m]
150 45
150 7
150 45
150 45
150 45
150 45
150 45
150 45
150 75
150 75
® is a registered Danfoss trademark
FC 300 Design Guide
3 cables [m] 4 cables [m]
8 6
4 3
20 8
5 4
20 11
20 6
20 11
20 11
50 37
50 37