Brodersen UDC-35 Bedienungsanleitung Seite 31

6. PID REGULATOR.
When selecting the regulator mode the 3
outputs can be defined as:
Relay 1: Energized below setpoint (Heating).
Relay 2: Energized above setpoint (Cooling).
Relay 3: Energized outside a band symme-
trical around the setpoint (Alarm).
If unnecessary output activity and pendling
should be avoided a dead band can be defi-
ned thus suspending the outputs 1 and 2.
Dead band (db)
Output
1
2
3
Sp
Alarm
In applications where only 1 or 2 outputs
are required, the outputs 2 and 3 can be
disabled, see section 3.3.
SIMPLIFIED BLOCK DIAGRAM.
Process
1
P = x e (t)
Pb
1 x ∫ e(t) dt
Pv I =
i
Sp e
de(t)
D = x
d
dt
t puls
B =
t puls + tpaus
P: Proportional element. I: Integral element. D:
Derivative element. B: Bias element (keep func-
tion). K: Constant (multiplum of gain inside and
outside the regulator). Sp: Set-point. Pv: Process
value. e: Error. PW:Pulse width control.
UDC-35 Digital Panel Controller - 31
Proportional Element (P).
The proportional element ensures that the
output is regulated proportionally to the
error in a band around the setpoint referred
to as proportional band (Pb). Outside Pb
the output will be constantly either ON or
OFF.
Integral Element (I).
The purpose of the integral element is to
correct for the stationary error introduced
by the load and definite gain of system.
Derivative Element (D).
The derivative element prevents over/
undershoot by predicting the future process
value from the actual rate of change.
Pv
Bias Element (B)/Keep Function.
The bias element is introduced to compen-
sate for the undesired dead band caused
by the non continuity of the A to D conver-
ter:
e = 0 for Pv = Sp ± 1 LSB
The bias function is only active inside the
K
defined dead band.
The bias function can be assigned to output
relay 1 or 2, or switched off, and the pulse
and pause time are individually adjustable.
+
PW
Pv
Sp
Out-
put
Dead band (db)
T
Pulse
t
T
Pause