Version 2.02 15.05.2007
Function of VS 3000
9
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E 2007 - ECKELMANN AG | BERLINER STRASSE 161 | 65205 WIESBADEN | TELEFON +49(0)611 71 03-0 | FAX +49(0)611 71 03-133
Neutral zone (NZ)
t
0
t
0 Setp
- 1,0 NZ
t
0 Setp
- 1/2 NZ
t
0 Setp
+ 1/2 NZ
I action
increase
I action
hold
I action
decrease
I action
hold
t
0 Setp
t
0 Setp
+ 1,0 NZ
Suction pressure
Time
VS 3000 control algorithm LP combined controller
- part-load operation -
Neutral zone (NZ)
t
0
t
0 Setp
- 1,0 NZ
t
0 Setp
- 1/2 NZ
t
0 Setp
+ 1/2 NZ
I action
increase
I action
hold
I action
decrease
I action
hold
t
0 Setp
t
0 Setp
+ 1,0 NZ
Suction pressure
Time
- load operation -
ZNR. 51203 64 130 E0
The controller output for the speed adjuster is computed from the P and I actions:
Controller outout = Paction+ Iaction
If all compressor stages are off and the actual value is greater than the setpoint (positive c ontrol error), the first
compressor stage (C1: Enable frequency changer) will be loaded immediately. Speed control is not activated
however before a delay has expired (time = basic load time C1); see also (Menu 3-2-3-a and 3-2-4-a). While the
delay times out, the compressor is operated at a definable minimum speed.
3.3 Loading and unloading fixed-speed compressors
Fixed-speed compressors can be loaded or unloaded if the required capacity cannot be supplied by changing
compressor speed,. When the variable-speed compressor has attained maximum speed, the fixed -speed com-
pressor having the shortest run time is cut in.
The variable-speed compressor is unloaded to a level corresponding to capacity without the addition of the
fixed-speed compressor. Compressors that can be allocated to the speed adjuster by base load rotation are the
last to be cut in.
When the variable-speed compressor attains minimum speed, the fixed-speed compressor having the longest
rung time is cut out. The variable-speed compressor is loaded to a level corresponding to capacity with the addi-
tion of the fixed-speed compressor.
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