Relay Output; Parallel Connection Of Motors - Danfoss FC 300 Design Manual

FC 300 Design Guide

Relay Output

Relay 1
• Terminal 01: common
• Terminal 02: normal open 240 V AC
• Terminal 03: normal closed 240 V AC
Relay 2 (Not FC 301 ≤7.5
• Terminal 04: common
• Terminal 05: normal open 400 V AC
• Terminal 06: normal closed 240 V AC
Relay 1 and relay 2 are programmed in par. 5-40,
5-41, and 5-42.
Additional relay outputs by using option module
MCB 105.

Parallel Connection of Motors

The frequency converter can control several par-
allel-connected motors. The total current con-
sumption of the motors must not exceed the rated
output current I for the frequency converter.
INV
This is only recommended when U/f is selected in
par. 1-01.
NB!
Installations with cables connected in
a common joint as in illustration 1 is
only recommended for short cable
lengths.
NB!
When motors are connected in paral-
lel, par. 1-02 Automatic Motor Adap-
tation (AMA) cannot be used, and par.
1-01 Motor Control Principle must be
set to Special motor characteristics
(U/f).
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).
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How to Install
kW)
MG.33.B7.02 - VLT is a registered Danfoss trademark