volume should be at
90
%
level
,
these are
9538
litres with a standard
vessel
(
according to bearing chart
).
T
he min
.
level should be adjusted
to
5
%
,
this corresponds to
181
litres
.
T
he volume should be displayed
in litres
.
C
arry out the adjustment in the signal conditioning instrument as
described in chapter
"
S
etup steps
"
.
N
o additional adjustment must
hence be carried out on the sensors
.
F
or the max
.
adjustment
,
fi
ll the
vessel up to the requested max
.
level and accept the actually
measured value
.
I
f this is not possible
,
the respective current value can
be entered alternatively
.
F
or the min
.
adjustment
,
empty the vessel up
to the min
.
level or enter the respective current value
.
T
o display the percentage level correctly
,
select under
"
M
easurement
loop
-
L
inearization curve
"
the entry
"
C
ylindrical tank
"
.
T
he display the volume in litres
,
you have to enter under
"
M
easure
-
ment loop
-
S
caling
"
as unit
"
V
olume
"
in litres
.
F
inally
,
the allocation is
carried out
,
in this example
100
%
≙
10000
litres and
0
%
≙
0
litres
.
P
ercent is selected as reference value for the relays
.
T
he mode of
relay
1
is set to over
fi
ll protection
,
relay
2
gets mode dry run protection
.
T
o ensure that the pump switches o
ff
in case of failure
,
the reaction in
case of failure should be adjusted to switching status
OFF
.
T
he
switching points are adjusted as follows
:
l
R
elay
1
:
S
witch
-
o
ff
point
90
%
,
switch
-
on point
85
%
l
R
elay
2
:
S
witch
-
o
ff
point
5
%
,
switch
-
on point
10
%
I
nformation
:
T
he switch on and o
ff
point of the relays must not be adjusted to the
same switching point because this would cause a permanent switchin
on and o
ff
when this threshold is reached
.
T
o avoid this e
ff
ect also with
fl
uctuating product surface
,
a di
ff
erence
(
hysteresis
)
of
5
%
is useful
between the switching points
.
8
.
2
W
eir control of a water power station
A
water power turbine must be protected against impurities in
fl
owing
water
.
T
hese impurities get stuck on the weir like on a screen
.
T
he
must be removed cyclacylly so that the max
.
fl
ow is ensured
.
I
f the
degree of impurity is too high
,
the water level in front of the system
raises because the total water volume can no longer
fl
ow through
.
T
he
di
ff
erence between level in front of and after the weir is hence a
measure of the degree of impurity and can be used to control the weir
cleaner
.
T
he water level in front of the weir
(
upstream water
)
and after the weir
(
downstream water
)
is measured each with a
VEGAWELL
72
HART
.
VEGAMET
625
generates the di
ff
erence
(
h
3
)
out of these two levels
(
measurement loop
3
).
I
f this di
ff
erence is too high
,
a signal will be
A
djustment
L
inearisation
S
caling
R
elay
F
unctional principle
E
xample
VEGAMET
625
•
D
ouble channel
HART
signal conditioning instrument
43
8
A
pplication examples
28970
-
EN
-
110801
