ELIS PLZEŇ a. s.
Project design, installation and service manual
Page 31 of 72
Electromagnetic flowmeter FLONET FH30xx
ELIS PLZE
Ň a. s., Luční 425/15, 301 00 Plzeň, Czech Republic, phone.: +420 377 517 711, fax: +420 377 517 722
Es 90678K
The output parameters of the frequency output are influenced by the capacity of the connected cable.
When transmitting a frequency output signal with a value reaching up to 10 kHz over long distances,
this negative effect on the quality of the transmitted signal at the evaluation point must be considered.
Multifunction outputs
– selectable functions
•
Pulses/frequency for Q+
•
Pulses/frequency for Q
–
•
Pulses/frequency for IQI
•
Q > Qmax
•
|Q| > Qmax
•
Output negation
Pulse number determination for the pulse output
Restrictive conditions in setting the pulse output parameters:
•
Maximum output frequency: f
max
= 100Hz
•
The middle period between pulses
M
shall be equal to or wider than the pulse width
P
.
Breaching this condition will result in an error message.
It holds:
M
P
P
M
T
In selecting the pulse number, the following requirement shall be met:
Q
max
≤ 3.6 × V × f
max
(m
3
/h, l/imp, imp/s)
where:
Q
… fluid flow rate
(m
3
/hod)
V
… volume per one pulse
(l)
P
… pulse length
(s)
f
… pulse output frequency
(Hz)
T
… cycle length
(s)
The flowmeter software permits setting the
V
values in steps shown in the table below:
V (l)
0.001 0.01 0.1 1 10 100 1000 10000
The pulse length in cases of electronic determination of the fluid volume passed through the
sensor is recommended to be set at P
min
= 5ms, which meets the condition for f
max
at the pulse
output equal to 100Hz. In cases of electro-mechanical counters, P
min
is usually set at 50ms,
corresponding to the maximum frequency at the pulse output of 10Hz.
Example:
Assume that a user specified for their flowmeter of DN100 the maximum operating flow rate:
Q
max
= 150 m
3
/h (Q
max
= 41.66 l/s
… v 5.3 m/s)
For the fluid volume corresponding to one pulse (of length 5ms, f
max
100Hz) it holds:
P + M = T
f =
1
T
