Power and Energy

Power and Energy is a tab used to configure power and energy measurement performed by the LK4. In combination with the Scheduler function, it allows measuring energy consumption within selected time intervals, e.g., for different tariffs.

Starting from software version SW 1.24, it also enables reading dynamic energy prices from an external source (API) or setting a fixed energy price.

Page elements

1. Section with readings and configuration of power and energy measurement.

   Contains:

   • setting the name,
   • power and energy readings,

   • changing the unit of measurement,

     Impact of the unit of measurement option on power and energy values

     Selecting this option can affect the displayed power value and energy accumulation. The impact varies depending on the selected measurement inputs (I and U):

     I = INPAX and U = INPAX or constant voltage

     Select W or kW - the power value is converted (e.g., 0.8 kW or 800 W).
     The selection does not affect energy accumulation.

     I = INPDX and U inactive

     Select from W, l/min, and m3/h - the power value remains the same in each case but is valid only for W.
     The selection does not affect energy accumulation.

     I = mX and U inactive

     Select from W, kW, kW -> W, and W -> kW.

     • kW - the value from variable mX is treated as power in kW.
     • W - the value from variable mX is treated as power in W.
     • kW -> W - the value from variable mX is treated as power in kW but displayed as power in W (numerical value multiplied by 1000).
     • W -> kW - the value from variable mX is treated as power in W but displayed as power in kW (numerical value divided by 1000).

     Energy is calculated based on how the mX variable is treated (W or kW); depending on the selection, the accumulation rate differs by a factor of 1,000 (the energy unit is always kWh).

   • selecting measurement inputs,

     Input selection and energy measurement

     Energy is calculated in three ways depending on the selected inputs:

     I = INPAX and U = INPAX or constant voltage

     Calculated based on I and U components, then accumulated over time.

     I = INPDX and U inactive

     Pulse counting and conversion to energy based on a specific factor. Changing the factor alters the accumulated energy value, as the system stores a pulse count that is scaled by that factor.

     I = mX and U inactive

     The value is treated as power and then accumulated over time — just like the result based on I and U components in the first case.

     The pulse count is stored in a variable separate from the accumulated energy value; consequently, changing the input setting from INPDX to another (or vice versa) may result in a change to the energy value.

   • setting the pulse-to-unit conversion factor,

   • field for entering a new energy measurement value,
   • enabling energy counting (Count energy).

2. Energy value retention function – when the Preserve energy reading option is enabled, the LK periodically saves the current energy counter values so they are not lost in the event of a device restart.

3. Dynamic energy prices section. Added in SW 1.24.

   The function enables periodic reading of the energy price and making it available in the system as a variable.

   The form contains:

   • Enable this function – activates the energy price reading mechanism.
   • Selection of price source:
     • Dynamic prices – price retrieved from the selected API,
     • Fixed prices – manual entry of a fixed value.
   • Offset field – allows adjusting the retrieved price by a specified value.
   • Selection of API source (e.g., PSE RCE).
   • Configuration save button.

   When the function is enabled, the energy price is:

   • read cyclically every 15 minutes,
   • read immediately after the function is activated,
   • stored in the system variable powerPriceFVal,
   • stored in the variable m1.

   The m1 variable can be used in other device functions, such as:

   • Events,
   • MQTT Client,
   • HTTP Client,
   • OLED / VOLED,
   • LTE Modem.

   If the dynamic energy price function is active, other readings should not be mapped to the m1 variable.

   The currently retrieved energy price is displayed at the bottom of the section.

Setting the energy value

The energy reading in the field will change only when the Count energy option is enabled. Therefore, before setting a new energy value, it is recommended to activate this option first. Otherwise, the set value will appear in the reading field only after Count energy is enabled.