Sontex Supercal 531 - 3.6 Energy metering

Manual Integrator Supercal 531 06-06-2011 16
high measuring resolution and high measuring reliability. To improve the measuring reliability, a
coherence test (check of the logical sequences of the values) has been implemented.
The mains-supplied integrator Supercal 531 measures the „temperature high“ and „temperature
low“ every 3 seconds.
The battery-supplied (battery type C or D) integrator measures the temperatures every 30 sec-
onds.
3.5.2 Tolerated errors and limit values
For firmly connected temperature sensors, the maximum tolerated error (in %) is calculated acc. to
the following formula:
E
t
= ± ( 0.5 + 3 ∆
min
/ ∆ )
∆
min
= admissible minimum temperature difference = 3 K
(Acc. to MID EC type examination certificate)
The screws of the terminals of firmly connected sensors are secured with adhesive seals. A sub-
sequent exchange of the temperature sensors is not possible without damaging the seals.
The integrator software checks if the measured temperatures are within the admissible measuring
range.
If the limits of the measuring range are exceeded the integrator indicates a measuring error.
3.6 Energy metering
3.6.1 Error limits
A heat flux can be calculated on the basis of its mass, its specific heat capacity and the tempera-
ture difference.
The difference of the enthalpy between „temperature high“ and „temperature low “during a set time
t is integrated. The equation to calculate the heat energy acc. to EN 1434-1, point 8, is applied in
this case.
The admissible error is calculated as follows:
Ec = ± ( 0.5 + ∆
min
/ ∆ )
The minimum temperature difference ∆min depends on the assembly of the components. If the
integrator and the temperature sensors are checked as one unit, the min. temperature difference is
2 K acc. to the PTB-approval and 3 K acc. to the MID-approval.
To receive the EC-prototype test certificate, at least 3 K has to be reached.
3.6.2 Cooling energy
If an energy meter is installed in the return pipe to measure the cooling energy, the „temperature
sensor low“ is installed in the supply and the „temperature sensor high“ in the return pipe.
By default, the integrator Supercal 531 is checked acc. to the metrological measuring points of
EN1434 (2006) for cooling and heating energy before leaving the factory.