Version 2.02 15.05.2007 Function of VS 3000
36
With HP combined control the available number of fans as a function of expansion stage is accordingly one less
than with step control. The reason for this is that the fan output following the last definable fan output
(No.Cond.Stages XX, Menu 3-1) is used for toggling to fixed-speed operation.
L1 L2 L3 L4 Ln Ln+1
0-10V
VS 3000
Speed
adjuster
Power supply
ZNR. 51203 74 430 E0
Enabling
Operation
by power supply
Control signal
With a positive control error, the speed adjuster is enabled through the first capacity stage of the VS 3000. De-
pending on the control error, a speed setpoint is calculated by a PI control algorithm and supplied to the speed
adjuster through an analog output (0 - 10 V). At maximum speed, the next capacity stage is loaded with a set
delay.
The control signal for the first fan stage is reduced to minimum speed. Fans that have been shut down by the
motor overload cutout are not considered for control. Fixed-speed mode is activated with the stage
No.Cond.Stages + 1 when pressure reaches a defined limit. The speed adjuster is disabled in fixed-speed
mode. Then the first fan is disconnected from the speed adjuster and connected to fixed-speed power sup-
ply.The run-up speed curve for a system equipped with five fans is illustrated in the following diagram:
t
Speed [%]
100%
Speed
minimum
Start delay
Fan stage
Operation by
power supply
stage 6
Fan 5
Fan4
Fan 3
Fan 2
Enabling Speed
adjuster stage 1
ZNR. 51203 74 630 E0
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