Installation, operating and maintenance manual
UNIGAS 300
DDG6004MHGB/08-2017/Rev.A2 Software version from M 1.3.40 and D 2.3.37
52
13 Determination of volume difference when two im-
pulse inputs are used
UNIGAS 300 features an alarm function for the volume difference between counters 1 and 2. This refers to
counters connected to inputs 1 and 2 (non-converted values).
For that purpose an additional counter Vm2’, which increases simultaneously with counter Vm2, is connected
to input 2. This counter is not readable and it is only used to determine the volume difference.
Every 5-min interval the volume difference is determined according to the following formula:
Volume difference = |Vm2’ – Vm1|
If the volume difference exceeds the preset alarm value, UNIGAS 300 will carry out the following actions:
•
status register 2.12 (alarm_volume_difference) is activated
•
event is recorded in the status log book and in the interval logging of that moment
•
Vm2’ is set equal to Vm2, so the volume difference can again be determined in the next period.
The graph of the above function is shown below.
Vm2'
Vm2' = Vm2
Vm2
Vm1
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When the interval logger is read out afterwards, the logging statuses show whether a volume difference has
occurred. If so, the impulse input of the gas meter or the connection between the gas meter and UNIGAS 300
must be inspected.
The trigger value of the volume difference can be adjusted by means of UNITOOL using register C.92.9 (see
chapter 10). If a value “0” is programmed the function is switched off.
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