Operating instructions
cod. 1592001300
1592001300 XC440C gb r1.0 07.06.2004.doc
rel. 1.0
Page
18 / 28
13. Type of regulation
13.1 Dead band – Only for compressors
This kind of regulation is available only for compressors. The neutral zone (Pbd) is symmetrical
compared to the target set point, with extremes: set+Pbd/2 ... set-Pbd/2. If the pressure
(temperature) is inside this zone the controller maintains the same number of loads switched on
and off, without changing anything.
When the pressure (temperature) go out from the zone, regulation starts. If the pressure is
greater than SET+Pbd/2, the loads are switching on with timing given by parameters: don and
doF.
A load is turned on only if the his safety times onon, oFon, donF are over.
Regulation stops when the pressure (temperature) come back into the neutral zone.
In the following a simplify exemplum that explains the regulation in neutral zone for compressor
homogeneous with 1 step for each compressors. The safety times onon, oFon and donF are
not considered. In the real regulation the a load is entered or turned off only if these times are
over.
Ex. Dead band control, compressors with same capacities, 1 step for each compressor.
In this example:
oA1 = cPr; oA2 = cPr; oA3 = cPr; oA4 =nu; number of compressors
CtyP = SPo homogeneous
compressors;
rty = db dead band regulation
Sty = yES rotation
FdLy = no “don” delay not enabled at first calling after an equilibrium condition.
dLF = no “doF” delay not enabled at first calling after an equilibrium condition.
S e t
&
Com pressor
Status
7LPH
Pressure
2Q
& 2Q
& 2Q
Compressor inserction area
neutral zone
don
doF
don
doF
GR)
GRQ
Delay
functioning
7LPH
7LPH
S e t + (P b d/2 )
S e t - (P b d /2 )
Compressor disconnection area
