Xylem WTW DIQ/S 281, Руководство по эксплуатации

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Outputs DIQ/S 281
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Monitoring limit-
ing values using
one or two relays
figure 6-1 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.
6.2.3 Proportional output
In the case of proportional output, a relay switches cyclically on and off in a
defined measured value range (proportional range). At the same time, the relay
switches with a:

duration of operation that corresponds to the measured value (pulse-width
output, see page 86) or
 switching frequency (frequency output, see page 86).
1 Upper limit value (relay 1) exceeded
2 Selected switching delay t1 for relay 1 1 expired
Relay 1 switches
3 Hysteresis for upper limiting value (relay 1) undercut
4 Selected switching delay t1 for relay 1 1 expired
Relay 1 switches back
5 Lower limit value (relay 2) undercut
Selected switching delay t2 for relay 1 1 expired
Relay 2 switches
Time
Measured
value
UL
LL
Hysteresis UL
Hysteresis LL
3
5
Relay 1
Relay 2
4
1
2
t1
t1
6
t2 t2