13
Doc.-no.: DPC200-AC_01_EN
Issue: 07/2019
OPERATION
5.6 Threshold calculation
NOTICE
The device requires a minimum pressure to calculate a volume
flow.
Minimum pressure =
0.5 % of the product mesuring range
PRESSURE < 0.5 % measuring range =
Display shows
0 m
3
/h
Minimal flow:
V_min = √(0.005 x measuring range) x k
Maximal flow:
V_max = √(measuring range) x k
Exampel: Threshold calculation
The set limit value must be between minimum and maximum flow.
As reference device we choose DPC200-AC with a measuring range of 0...1000 Pa.
The limit value calculation formula:
V = √ΔP × k
Given values:
Measuring range =
0...1000 Pa
; k-factor (k) =
116
; Limit value (V) =
1,200 m
3
/h
It follows:
ΔP= (V / k)
2
= (1,200 / 116)
2
=
107 Pa > 5 Pa = 0.5 % of the measuring range
Minimal flow:
V_min = √(0.005 x 1000) x 116 =
259 m
3
/h
Maximal flow:
V_max = √(1000) x 116 =
3,668 m
3
/h
Result:
The limit value of
1,200 m
3
/h
is between V_min and V_max and adjustable by
our
DPC200-AC-R (0...1000 Pa)
.
5.7 Function alarm output
The DPC200-AC has an open collector alarm output; depending on the operating mode
the function is different. At the
alarm event
a contact between terminal no. 7 and no. 8
gets low-resistive and can be loaded with a maximum of 30 V DC/ 30 mA. When the alarm
is switched off the contact will be high-resistive.
During alarm state in the control mode / measuring mode an exclamation point (!)
is displayed (2nd line / 16th character).
Control mode:
In order to recognize the limits of control, the alarm output in the control
mode refers to the set maximum output voltage (MaxU
out
). MaxU
out
can be set in the menu
item „output voltage“.
In the default setting the value is set to 10 V DC.
Alarm ON: Output voltage for 12 seconds constantly greater than: 0.95 • MaxU
out
Alarm OFF: Output voltage for 12 seconds constantly less than:
0.9 • MaxU
out
Measuring mode:
For limit value monitoring a limit value can be entered. This value is
set in the menu item „limit switch“. The previously set parameters are taken into account
(unit, parameter, k-factor and the measuring range).
As default setting the limits are not active - Display - 2nd line: „OFF“
Alarm ON: Measurement for 12 seconds constantly greater than 1.0 • limit value
Alarm OFF: Measurement for 12 seconds constantly less than 0.95 • limit value
