Pressure sensors
Pressure transmitters with casing (current output) CAU-T series
AS SEN PD 2009-08-03
Please read Cautions and warnings and Page 6 of 8
Important notes at the end of this document.
Symbols and terms
1)
Storage temperature range T
st
A storage of the pressure sensor within the temperature range T
st,min
up to T
st,max
and without applied pressure and supply voltage will not affect the performance of the pressure sensor.
2)
Operating temperature range T
a
An operation of the pressure sensor within the temperature range T
a,min
up to T
a,max
will not affect the performance of the pressure sensor.
3)
Compensated temperature range T
c
While operating the pressure sensor within the temperature range T
c,min
up to T
c,max
,
the deviation of the output signal from the values at 25 °C will not exceed the temperature coefficients.
Out of the compensated temperature range, the deviations may increase.
4)
Rated pressure p
r
Within the rated pressure range 0 up to p
r
(symmetrical output: –p
r
up to +p
r
) the signal output characteristic corresponds
to this specification.
5)
Overpressure p
OV
Pressure cycles within the pressure range 0 up to p
ov
will not affect the performance of the pressure sensor.
6)
Supply voltage V
CC
V
CC,max
is the maximum permissible supply voltage, which can be applied without damages.
V
CC,min
is the minimum required supply voltage, which has to be applied for normal operation.
7)
Working resistance R
L
Depending on V
S
, the maximum working resistance is R
L
≤ (V
S
– 10 V) / 0.02 A.
8)
DC break down voltage V
is
The pressure sensor withstands a high voltage between the stainless steel casing and the electrical connection
I+ and I– (short circuited) without damage.
9)
Offset I
CC0
The offset I
CC0
is the signal output I
CC
(p = 0) at zero pressure.
10)
Signal span (Full Scale)
Simple output: I
FS
= FS = I
CC
(p
r
) – I
CC0
Symmetrical output: I
FS
= FS = I
CC
(+p
r
) – I
CC
(–p
r
)
11)
Nonlinearity L (including pressure hysteresis)
The nonlinearity is the deviation of the real sensor characteristic I
cc
= f(p) from the ideal straight line.
It can be approximated by a polynomial of second order, with the maximum at p
x
= p
r
/ 2.
The equation to calculate the nonlinearity is:
r
x
0ccrcc
0ccxcc
p
p
I)p(I
I)p(I
L −
−
=
12)
Response time t
10-90
Delay between a pressure change (10 ... 90% p
r
) and the corresponding signal output change (10 ... 90% FS).
13)
Supply voltage rejection SVR
While varying the supply voltage within the range V
CC,min
up to V
CC,max
at constant pressure and temperature,
the signal output change will not exceed SVR
max
.
14)
Temperature hysteresis
The temperature hysteresis is the change of offset, starting from the value at 25 °C after a temperature change
and return to 25 °C. Determined during temperature cycles in operating temperature range (cycles with 1 K/min).
15)
Temperature coefficient of offset TCI
CC0
Offset at temperature T
x
: I
CC0
(T
x
) = I
CC0
(25 °C) + I
FS
(25 °C) · (T
x
– 25 °C) · TCI
CC0
Values are valid within the compensated temperature range T
c,min
up to T
c,max
Out of the compensated temperature range, the deviation may increase.
16)
Temperature coefficient of span TCI
FS
Span at temperature T
x
: I
FS
(T
x
) = I
FS
(25 °C) · [ 1 + (T
x
– 25 °C) · TCI
FS
]
Values are valid within the compensated temperature range T
c,min
up to T
c,max
Out of the compensated temperature range, the deviation may increase.
