MULTICAL® 803
116
Kamstrup A/S · Technical description · 5512-2360_A1_
GB
_02.2019
4-wire sensor pair
For installations requiring longer cables than listed in the table above, it is recommended to use 4-wire sensor pairs.
By default, MULTICAL
803 is prepared for 4-wire connection on all temperature sensor inputs.
MULTICAL® 803 has a “real” 4-wire measurement, which uses two conductors for measuring current and two
conductors for measuring signal, which means that the measurement is in theory uninfluenced by long sensor
cables. In practice, cables ought not to be longer than 100 m and it is recommended to use 4 x 0.25 mm
2
.
As the 4-wire signal inputs have a very high impedance, a disconnected wire could lead to an arbitrary temperature
and the information code “Above the measuring range” (sensor disconnected) or “Below the measuring range”
(sensor short-circuited) would be displayed
The connection cable ought to have an outer diameter of 5-6 mm in order to obtain optimum tightness of both
MULTICAL
803 and the screw joint for the 4-wire sensor. The isolation material/cover of the cable ought to be
selected on the basis of the maximum temperature in the installation. PVC cables are normally used up to 80
°
C and
for higher temperatures, silicone cables are often used.
Note: When presetting temperatures of 4-wire connections, it is important to insert jumpers in the connection
terminals of the 4-wire sensor inputs that have preset (e.g. jumper between connection terminals 4-8 and jumper
between connection terminals 7-3 at preset of t2) as described in the paragraph above about 2-wire sensors.
7.7
Auto Detect Pt100/Pt500
MULTICAL® 803 can be delivered with the possibility of automatic detection of the connected Pt sensor type, either
Pt100 or Pt500. However, it is possible to lock the temperature sensor type on the MULTICAL® 803 country code so
that the type is locked to either Pt100 or Pt500. For MULTICAL® 803, with the possibility of Auto Detect Pt
(Pt100/Pt500), it is also possible to choose via METERTOOL HCW whether the calculator must be set to Pt100, Pt500
or Auto Detect Pt. See the technical description of METERTOOL HCW (5512-2097).
With active Auto Detect Pt in MULTICAL® 803, the registration of the connected Pt sensors takes place when the
calculator top and bottom are assembled after separation as is the case of Auto Detect UF (ULTRAFLOW® X4), see
paragraph 8.1.1.
Any conversion from one Pt sensor type to another can only be carried out if it is ensured that MULTICAL® 803 has
measured absolutely correctly for one of the Pt sensor types and that a clear error has been measured for the other
Pt sensor type, see criteria for conversion in the table below.
Auto Detect Pt criteria for change
Pt100
Pt500
Result
t1
t2
t3
t4
t1
t2
t3
t4
MULTICAL® 803 configuration
OK
OK
OK
OK
Error
Error
Error
Error MULTICAL® 803 is set to Pt100.
Error
Error
Error
Error
OK
OK
OK
OK
MULTICAL® 803 is set to Pt500.
Note: Inputs without connected Pt sensors are not included in the Pt type control.