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MULTICAL® 801
44
Kamstrup A/S · Technical Description · 5512-571_R1_GB_11_2016
6.8
Temperature measurement
MULTICAL
801 is fitted with a high-resolution analog/digital converter, which measures the temperatures T1, T2
and T3 with a resolution of 0.01
°
C. The same measuring circuit is used for all three temperature inputs in order to
obtain the lowest possible measuring error of the temperature difference. Prior to each temperature measurement,
the internal measuring circuit is automatically adjusted based on built-in reference resistors at 0
°
C and 100
°
C
respectively. Very accurate measurements and an almost immeasurable long-term stability is hereby obtained.
Current T1
MULTICAL
801 measures all temperatures every 10 seconds if supply voltage is connected. If the supply voltage
is disconnected and the meter is driven by the backup battery, temperature measurements are carried out with
every integration (energy calculation), not at shorter intervals than 10 s however.
The temperature range of the measuring circuit is 0.00
°
C…185.00
°
C. For disconnected temperature sensor,
200.00
°
C is shown and for short-circuited temperature sensor 0.00
°
C is displayed. In both cases the info code for
sensor error will appear.
In order to reduce the influence of hum, which can e.g. be picked up in long sensor cables, double measurements
with a timing difference of half a period of time are carried out, and the average of the two measurements is the
temperature measurement used for calculation and the one displayed. The hum suppression is optimized to either
50 Hz or 60 Hz depending on the selected country code.
6.8.1
Measuring current and power
Measuring current is only sent through the temperature sensors during the short duration of the temperature
measurement. The effective power which is deposited in the sensor elements is thus very small, and its influence
on the self-heating of the temperature sensors is typically less than 1/1000 K.
Pt100
Pt500
Measuring current
<
3 mA
<
0.5 mA
Peak power
<
1.5 mW
<
0.2 mW
RMS influence
<
10
µ
W
<
1
µ
W