MULTICAL® 801
Kamstrup A/S · Technical Description · 5512-571_R1_GB _11.2016
77
8.2
Cable influence and compensation
8.2.1
Two-wire sensor pair
MULTICAL
801 is in standard version fitted with 4-wire sensor inputs for all three inputs, T1-T2-T3. Mostly only
relatively short temperature sensor lengths are needed for small and medium-size heat meters, which means that
2-wire sensor sets can be used with advantage.
Figure 15
Connection of 2-wire sensors by means
of jumpers (type: 66-99-209)
Cable lengths and cross sections of the two sensors, which are used as temperature sensor pair for a heat meter,
must always be identical, and cable sensors must neither be shortened nor extended.
The limitations connected to the use of 2-wire sensor sets according to EN 1434-2 appear from the table below.
Kamstrup supply Pt500 sensor sets with up to 10 m cable (2 x 0.25 mm
2
)
Cable cross
section
[
mm
2
]
Pt100 sensors
Pt500 sensors
Max. cable length
[
m
]
Temperature
increase
[
K/m
]
Copper @ 20
°
C
Max. cable length
[
m
]
Temperature
increase
[
K/m
]
Copper @ 20
°
C
0.25
2.5
0.450
12.5
0.090
0.50
5.0
0.200
25.0
0.040
0.75
7.5
0.133
37.5
0.027
1.50
15.0
0.067
75.0
0.013
Table 6
8.2.2
4-wire sensor pair
For installations, requiring longer cables than listed in the table above, we recommend the use of 4-wire sensor
sets.
MULTICAL
801 has a ”real” 4-wire construction, which uses two conductors for measuring current and the two
conductors for measuring signal, which means that the construction is in theory uninfluenced by long sensor
cables. In practice, cables ought not to be longer than 100 m and we recommend the use of 4 x 0.25 mm
2
.
