Instructions for Use
– SCHMIDT
®
Flow Sensor SS 20.700
Page 27
Pulse outputs
The pulse outputs represent the flow velocity w
N
as an alternative to the
analog output.
The basic version of the
SS 20.700
maps the flow velocity w
N
propor-
tional to a frequency range [0
… f
max
] with selectable maximum fre-
quency f
max
(see Figure 5-4).
Figure 5-4 Example for f
max
= 100 Hz
𝑓
𝑚𝑎𝑥
= 10 … 100 𝐻𝑧
max
,
max
N
w
f
f
N
w
max
,
max
N
V
f
f
N
V
N
V
: Standard volume flow
The volume flow
𝑉̇
𝑁
and the pulse valence V
N,Imp
(= volume per pulse)
can be determined on base of the actual output frequency, the meas-
uring range w
N,max
of the sensor and the inner pipe diameter D:
𝑉̇
𝑁
= 𝑤
𝑁
∙ 𝑃𝐹 ∙ 𝐴
𝐷
= 𝑤
𝑁
∙ 𝑃𝐹 ∙
𝜋
4
∙ 𝐷
2
;
𝑉
𝑁,𝐼𝑚𝑝
=
𝑉̇
𝑁,𝑚𝑎𝑥
𝑓
𝑚𝑎𝑥
Exceeding the measuring range is also output linearly up to 110 % of
the measuring range. Higher values of flow velocity or volume flow are
limited to 110 % of the measuring range.
Optional the sensor can be configured by ordering to supply pulses
with a predefined pulse valency (e.g. 1 m³/pulse).
For this, the inner pipe diameter must be specified when ordering (at
minimum DN40).
If an error occurs, f = 0 Hz resp. no pulses will be output. The current signal
level remains unchanged.
Note:
The relay can be used as a S0-Interface
25
according EN 62053-31.
25
Former standard: DIN 43 864
f
Out
[Hz]
0
110
w
N
[%]
100
0
20
110
40
80
60
100
40
20
60
80
