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5.6.4 Switching modes for step control
There is a choice of three switching modes (menu 3-2-2-1-b) for the step control:
•
Direct
No star-delta switching
•
KKGG
The first half of the relay outputs actuates the star operation of the fan motors (K = low speed) while the
second half of the outputs actuates the delta operation (G = high speed). A maximum of 6 fans can be
controlled.
•
KKKG
The fan motors are loaded or unloaded with all except the last relay stage. With the last relay stage, all
fans are switched simultaneously from star operation (K = low speed) to delta operation (G = high
speed). A maximum of 11 fans can be controlled.
The following table shows the control of the fan outputs using the example of a system with two fans and four
fan stages using the KKGG operating mode:
Switching sequence KKGG
Fan stage:
L1
Stern
S1 L2
Stern
S2 L1
Δ
S3 L2
Δ
S4
Shifting up
Fan 1: OFF / Fan 2: OFF
F
Fan 1; low speed / Fan 2: OFF
F
F
Fan 1; low speed / Fan 2: low speed
F
F
F
Fan 1; high speed / Fan 2: low speed
F
F
F
F
Fan 1; high speed / Fan 2: high speed
Shifting down
F
F
Fan 1; high speed / Fan 2: OFF
F
F
F
Fan 1; high speed / Fan 2: low speed
Summary of Contents for VS 3015 C
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