ECKELMANN VS 300, Operating Instructions Manual

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Function of VS 300
25 Doku-Version 2.05 - Firmware 2.10 - 15. September 2017
4.3.5 Control algorithm with speed controller
Low pressure measured by an A/D converter is compared with the setpoint (see section 4.3.10 Determining the
Low-Pressure Setpoint). The following relationship applies:
Control error
When the control error is positive, a PI control algorithm calculates a speed setpoint that is transmitted to the
frequency changer through an analog output (0-10 V). The frequency changer controls compressor speed to the
defined setpoint.
The frequency changer/speed adjuster is enabled by means of the first capacity stage. When the frequency
changer/speed adjuster has been enabled, the compressor runs at minimum speed until the basic and variable
load times have expired, after which speed is determined by the PI control algorithm.
Following restart of the controller (after a power failure, etc.), the analog output is maintained at minimum speed
for 1 minute after the frequency changer/speed adjuster has been enabled.
T ime
VS 300 Compressor setup characteristic
Enab l ing
speed ad j uster
Minima l
speed
1 Minute
Basic + variab l e
l oad time
I nput signa l [ V ]
Contro l
Request
ZNR
.
51203
6
3
730
E0
When the control error is negative, the speed adjuster is disabled by means of the first capacity stage of the as­
signed VS 300 control loop as soon as speed drops to low level and the basic unload time and variable unload
time have elapsed.