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Technical principle
Calculation of energy is based on the following formula:
Energy = Volume x (THot - TCold) x Kfactor (Ti)
Volume: Volume [m3] of a given amount of volume pulses
THot: Measured temperature in the hot line
TCold: Measured temperature in the cold line
Kfactor (Ti): Thermal coefficient of media enthalpy and heat content
The energy calculation is made by a counter and depends on temperature difference, pulse input frequency and legal requirements.
The calculator always carries out at least one energy calculation every 2 seconds. If the connected flowmeter has not sent enough pulses the energy calculation and flow indication is also based on the 8 seconds value.
Data memory
The FUE950 has a history memory of 24 periods (months, weeks, days). The following values are stored monthly, weekly or daily in the EEPROM on the programmed day of 1…31 (via software tool).
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Data logger memory (LOG)
The LOG of the calculator is stored every 24 hours with all cumulative values in the EEPROM. The storage frequency can be selected from various storage intervals (5, 6, 10, 12, 15, 20, 30, 60 minutes or the default setting of 24 hours). The data which are stored in the LOG could be read out using a software tool and can be used for evaluations.
Extract of possible LOG settings
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Storage Interval |
Values |
Number of data records |
Recording period |
|---|---|---|---|
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5 minutes |
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440 |
36.6 hours |
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15 minutes |
440 |
110 hours |
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1 hour |
440 |
18.3 days |
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24 hours |
440 |
440 days |
Maximal Values
The integrator creates max. values for power and flow rate based on consumption time, which are stored in the EEPROM. The integration intervals are adjustable to 6, 15, 30 or 60 minutes and 24h. Default setting is 60 minutes.
Tariff/Accounting date function
The calculator includes two independent memories in which the accumulated energy at two programmable tariff dates are stored.
- Last accounting date
- Last but one accounting date
Values stored
- Energy
- Volume
- Tariff counter 1
- Tariff counter 2
- Pulse counter 1
- Pulse counter 2
- Date
The integrator offers two optional tariff memories for monitoring plant load states. Here it concerns threshold value tariffs. Extensive tariff conditions make it possible to adapt the calculator individually to the required customer-specific applications.
Both tariffs are separately configurable and independent from each other. Energy or time can be measured alternatively per tariff register dependent on the tariff mode adjusted in each case.
With the "time triggered tariff function" the switch-on time and the switch-off time are adjustable independent from each other for each day of the week in steps of 15 minutes.
The following limit types are possible:
(This example applies to the display at 3 fractional digits after comma)
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Type |
Description |
Limit |
Limit resolution |
|---|---|---|---|
|
dT |
Temperature difference |
1 … 190 °C |
1 °C |
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-dT |
Negative temperature difference |
1 … 190 °C |
1 °C |
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TR |
Return temperature (low) |
1 … 190 °C |
1 °C |
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TV |
Forward temperature (high) |
1 … 190 °C |
1 °C |
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P |
Power |
10 … 2500 kW |
10 kW |
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Q |
Flow |
1 … 255 m3/h |
1 m3/h |
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FE |
"Theoretically forward energy" with return temperature of 0 °C |
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Z |
"Time triggered" counting energy |
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E |
"External" counting energy |
Error handling and memory
Events such as changes and faults are stored in a non-volatile memory with a capacity of up to 127 entries. The following events are recorded:
- Checksum error
- Temperature measurement error
- Error hours
- Start and end of test mode
If SITRANS FUE950 records an error, this will be automatically indicated by a "alarm symbol" on the display.
To protect the reading data, all the relevant data are saved in a non-volatile memory (EEPROM). This memory saves the measured values, device parameters and types of error at regular intervals.
The following events are recorded:
- Temperature sensor error
- Swapped hot and cold temperature sensors
- Battery low warning
- Power supply failure
- Optical communication warning
- RAM checksum error
Outputs/Inputs/Communication
Communication interfaces:
SITRANS FUE950 is fitted with an optical infra-red send/receive port in accordance with EN1434/IEC 61107, protocol standard, EN1434/EN 60870-3 (M-Bus protocol).
A reader head with a permanent magnet (IrDA-adapter) in accordance with EN 1434 can be used for readout data or communication with the parameterization software.
2 ports for optionally plug-in modules
The calculator features 2 ports for the plug-in modules.
One slot is for the function modules and the other for the communication modules.
Communication modules
The following communication modules are available as options: RS232 module, RS485 module and M-Bus module. The RS232 and RS485 communication modules are serial interfaces and permit data exchange with the calculator. For this purpose a special data cable is necessary.
The M-Bus module is a serial interface for communication with external devices (M-Bus Master/Centre). According to the M-Bus structure a number of calculators can be connected to a control centre.
Pulse input module
Two pulse inputs are available. The pulse value and the unit is configurable for energy, water, gas or electrical meter by parameterization software. Data are separate cumulated in different registers and are also stored on the two accounting day's (Tariff registers).
Combined pulse input/output module
Two pulse inputs combined with one pulse output are available on one module. The pulse inputs are configurable with value and the unit by parameterization software.
The pulse output is also programmable using the parameterization software.
Pulse output
The calculator provides levels for two optional external pulse outputs, which can be freely programmed using the parameterization software tool.
Default setting is a pulse output occurs per change in the least significant digit in the display with the unit and resolution selected by the device ordering.
Possible pulse output values
- Energy (default setting)
- Volume (default setting)
- Tariff energy 1
- Tariff energy 2
- Tariff condition 1, limit switch
- Tariff condition 2, limit switch
- Energy error
- Volume error
- Volume with specific resolution (0.1, 1.0, 10 or 100)
- Energy with specific resolution (0.1, 1.0, 10 or 100)
Combined current output module
Optional module with 2 passive 4 ... 20 mA outputs.
Possible output values:
- Power (default setting for output #1)
- Flow (default setting for output #2)
- Hot, cold or difference temperature
The settings can be configured by parameterization software. The current output module occupies both ports, means no other plug-in module will possible to plug in.
Module combinations
The calculator has a group of extension modules for communication and another group of extension modules for additional functionality. These modules are available first selected within the calculator, or for retrofitting in the field.
One single function module as well as one single communication module out of following modules is selectable.
Function modules:
- Pulse input module, 2 inputs
- Pulse output module, 2 outputs
- Combined pulse module 2 inputs, 1 output
- Combined current output module, 2 x passive 4 ... 20 mA
(occupies both ports)
Communication modules:
- M-Bus
- RS232
- RS485