This function block monitors the current load in a building and protects against overload. If the maximum permissible power [maxP] is exceeded, loads assigned to the function block are shed and blocked based on priority.
Only loads that can be switched, either directly, or via an interface can be used.
Table of Contents
|cP||Current power||Analogue input for current total power||kW||∞|
|Sl1-12||Status load 1-12||Digital input of the load’s current status.
When this input is used, you will be notified when the load is shed due to overload.
|R||Reset||Resets all outputs. As long as this input is active, the function block is disabled.||-||-|
|Ll1-12||Lock load 1-12||If the function block's maximum power capacity [maxP] is exceeded, power is made available by locking loads with higher priority.||-||-|
|AP||Available power||Currently available power until the maximum power capacity is reached.||kW||∞|
|maxPe||Maximum power exceeded||ON, when the maximum power capacity [maxP] is exceeded for 30 seconds||-||-|
|Abbreviation||Summary||Description||Unit||Value Range||Default Value|
|maxP||Maximum power||Defines the maximum power capacity||kW||0...∞||20|
|Configuration||Configure the individual loads of the Load Manager.||-|
The loads, including their power, that are to be shed in the event of an overload are specified in the configuration window that opens when the block is added or via the block's settings.
The top entry has the highest priority for load shedding, i.e. it is locked first. Should this be insufficient, additional entries are locked according to their priority:
In this example, we control two boilers, a charging station for an electric vehicle, and the sauna. Up to 12 loads can be configured using the function block.
The inputs and outputs of the block are then connected in programming:
The status of the loads is determined via the status inputs of the function block, in the example SI1 - SI4.
Although the status inputs are not required for operation, they allow the status of the loads to be displayed in the user interface and allow the function block to determine the speed of the load shedding.
The outputs of the function block, in the example Ll1 - Ll4, are used to lock the loads. An active output means a locked load.
Additional logic will most likely be required, since loads are rarely switched by the block alone, but are only enabled or disabled by the block.
The current total electrical power is transmitted to the function block via Input cP.
Parameter maxP specifies the maximum permissible electrical power.
Based on these two values the function block can detect an overload and determine whether shedding loads is needed.
As soon as an overload is detected, the first load is locked. If locking the first load does not resolve the overload, additional loads will be locked.
After locking one or more loads, a 10-second waiting period will allow the system to stabilize before the load condition is re-evaluated and, if necessary, additional loads will be locked or re-enabled.
Loads are re-enabled in reverse order once sufficient power is available again, i.e. the load's power +10 percent would not lead to an overload when it is switched on. Only one load is switched on at a time, 10 seconds after which the load condition is checked again.
The user interface shows the current load conditions and the status of the used loads: