wtw CL 298, Руководство по эксплуатации, Страница: 41 / 76

pH 298, LF 298, Oxi 298, Cl 298
Outputs
41
ba77196e03 07/2018
Monitoring limiting
values using one
or two relays
figure 5-1 Switching points for relays with the function of a limit indicator
A switching delay (t) can be set up for each relay for switching processes. This
is the time period for which a limiting value must be exceeded before the relay
switches. This prevents frequent switching if the measured values are close to
the limiting value.
5.1.2 PID controller (relay and current output)
With the function, PID controller , a relay or output can be used as a regulator.
The regulator can be configured as a P roportional regulator with switchable I nte-
gral and D ifferential regulator parts ( PID Controller).
By activating or deactivating the I ntegral ( ti ) and D ifferential ( td) regulator part,
the following regulator types can be configured:
1 Upper limit value (relay 1) exceeded
2 Selected switching delay t1 for relay 1 expired
Relay 1 switches
3 Hysteresis for upper limiting value (relay 1) undercut
4 Selected switching delay t1 for relay 1 expired
Relay 1 switches back
5 Lower limit value (relay 2) undercut
Selected switching delay t2 for relay 2 expired
Relay 2 switches
Regulator type
td [s] (
reset
time)
ti [s] (
hold-
back time)
P controller
0 0
Time
Measured
value
UL
LL
Hysteresis UL
Hysteresis LL
3
5
Relay 1
Relay 2
4
1
2
t1
t1
6
t2 t2