PTZ-BOX 5.0 User manual, document edition: 13
8
Function principle
1.2.1
General characteristics
•
The measurement is based on counting of the volume at measurement conditions, based on
amount of pulses from reed contact LF or high frequency HF sensor mounted in the head of
the gas meter or from direct readout of gas meter counter with use of its built-in encoder.
•
With built-in sensors device measures pressure and temperature of gas.
•
Device converts the counted gas volume at measurement conditions into volume at base
conditions (EN 12405-1:2018) and using pre-set gas parameters it computes value of energy
(EN 12405-2:2012).
•
Beside measurements and computation of current parameters, device also archives chosen
parameters and information about registered alarm states
–
available for later readout.
•
The incorporated display and keyboard enable to monitor current measurement data, peak
values and alarms as well as to adjust the basic operating parameters, such as time and date,
measurement input limits, transmission parameters, and the like. Any modification of
parameters both via transmission and with use of the keyboard requires user authorization.
•
PTZ-BOX 5.0 is a device powered by internal battery, but it also can be powered by external
power supply. In standard version, at typical operating conditions (1-2 readouts per month) 1
piece of battery allows up to five years of lifetime.
•
Device has functions, which allow to use it in control and telemetry systems. During use of
these features it is necessary to connect applicable type of AC power adapter, which
provides separation of intrinsically safe circuits and allows to power by external supply of
device. AC power adapter is an optional accessory.
1.2.2
Measurement
–
calculation cycles
PTZ-BOX 5.0 device operates by default in measurement-calculation cycle:
•
Every 30 seconds
–
when running in BATT mode (powered from internal battery),
•
Every 1 second
–
when running in FULL mode (powered from external power source),
•
Every 1 second
–
when display is turned on (in all power modes),
•
Frequency of mentioned cycles in BATT mode could be set in range of 6..30s (up to 60s when
device is non-MID version);
•
In every cycle, at first step device performs read of information about values of all measuring
inputs and calculates increments from chosen counting input. Basing on this input data PTZ-
BOX 5.0 calculates increment of volume at measurement conditions
dVm
, adds it up to
counter
Vm
and computes value of flow at measurement conditions
Qm
. At the same time,
device checks, whether new alarms have occurred or earlier alarm situations have been
closed.
•
In next step, basing on the current values of pressure
p1
, temperature
t
and programmed gas
parameters, unit calculates conversion factor
C
and then increment of volume at base
conditions
dVb
and flow
Qb
. Simultaneously there are calculated values of:
dE
,
dM
,
QE
,
QM
.
1.2.3
Emergency state
During typical usage of the device, depending on the appearance of alarm situation, it can operate
either in normal state or in emergency state. All parameters listed before are active in both states of
device operation (calculation of temporary values of flows and counters increments).
If the unit operates in normal state, all calculated increments are added up to main counters („n”
-
new value of parameter, „p”
- value from previous calculation cycle):
