Two-point controller
Switching controller with
two
switching statuses:
1.
Heating
switched
on;
r
output
Y1 = 1
2.
Heating
switched
off;
r
output
Y1 = 0
E.g. for temperature control with electrical heating (inverse operation)
or
cooling (direct operation)
Adjust cycle time Tp1 as follows:
Tp
Tu
1
0 25
<=
·
,
With higher Tp1, oscillations must be expected. Tp1 corresponds to the minimum cycle time (time in seconds) at 50 %
duty cycle.
Output Y1 (heating)
PD action
(
Tn
= 0
=
switched off Tn =
Î
)
The working point is in the middle of proportional band
X
p1
at 50 % duty cycle. In order to keep the control variable con-
stant, a defined quantity of energy dependent of set-point is required. This energy causes a permanent control devia-
tion, which increases with growing
X
p1
.
DPID action
By means of the I action, line-out is without permanent control deviation.
The static characteristic of a two-point controller is identical to the one of a continuous controller, with the difference
that a duty cycle instead of a linearly variable current signal is output (relay contact, logic signal 0/20mA or control out-
put 0/24V).
Working point Y
0
and cycle time Tp1 at 50% are adjustable.
The shortest switch-on or switch-off time is 100ms.
9499 040 50611
Controller
169
Controller behaviour
process value
Set-point
Xn100
Xn0
W0
Y0
Weff
W100
100%
0%
Y1
Â
Xeff
Xp1
Static
operating principle of a
two-point controller
Summary of Contents for KS 98
Page 8: ...Description 9499 040 50611 Construction 8...
Page 10: ...Important technical data 9499 040 50611 Further external in and outputs 10...
Page 12: ...Versions 9499 040 50611 I O modules for units with modular option c basic card 12...
Page 14: ...Front view 9499 040 50611 14...
Page 16: ...Mounting 9499 040 50611 16...
Page 26: ...Maintenance 9499 040 50611 Further information 26...
Page 36: ...Scaling and calculating functions 9499 040 50611 LG10 10s logarithm 36...
Page 74: ...Signal converters 9499 040 50611 MEAN mean value formation 74...
Page 128: ...KS98 I O extensions with CANopen 9499 040 50611 RM_DMS strain gauge module 128...
Page 132: ...CSEND Send mod blockno s 21 23 25 27 No 57 132...
Page 140: ...Description of KS98 CAN bus extension 9499 040 50611 140...
Page 202: ...Controller 9499 040 50611 Process value calculation 202...