Merge pull request #167 from alliander-opensource/feature/docs-on-links

no sensor on link

Author: petersalemink95

docs/user_manual/components.md

@@ -84,7 +84,8 @@ also modeled as `line`. A `line` can only connect two nodes with the same rated
 
 `link` is a {hoverxreftooltip}`user_manual/components:branch` which usually represents a short internal cable/connection between
 two busbars inside a substation. It has a very high admittance (small impedance) which is set to a fixed per-unit value
-(equivalent to 10e6 siemens for 10kV network). There is no additional attribute for `link`.
+(equivalent to 10e6 siemens for 10kV network). Therefore, it is chosen by design that no sensors can be coupled to a `link`.
+There is no additional attribute for `link`.
 
 ### Transformer
 
@@ -341,11 +342,13 @@ The table below shows a list of attributes.
 
 `power_sensor` is an abstract class for symmetric and asymmetric power sensor and is derived from
 {hoverxreftooltip}`user_manual/components:sensor`. It measures the active/reactive power flow of a terminal. The terminal is
-either connecting an `appliance` and a `node`, or connecting the from/to end of a `branch` and a `node`. In case of a
+either connecting an `appliance` and a `node`, or connecting the from/to end of a `branch` (except `link`) and a `node`. In case of a
 terminal between an `appliance` and a `node`, the power {hoverxreftooltip}`user_manual/data-model:Reference Direction` in the
 measurement data is the same as the reference direction of the `appliance`. For example, if a `power_sensor` is
 measuring a `source`, a positive `p_measured` indicates that the active power flows from the source to the node.
 
+Note: due to the high admittance of a `link` it is chosen that a power sensor cannot be coupled to a `link`, even though a link is a `branch`
+
 | name | data type | unit | description | required | input | update | output |                    valid values                     |
 | --- | --- | --- | --- | :---: | :---: | :---: | :---: |:---------------------------------------------------:|
 | `measured_terminal_type` | {py:class}`MeasuredTerminalType <power_grid_model.enum.MeasuredTerminalType>` | - | indicate if it measures an `appliance` or a `branch`| &#10004; | &#10004; | &#10060; | &#10060; | the terminal type should match the `measured_object` |

src/power_grid_model/enum.py

@@ -69,11 +69,11 @@ class MeasuredTerminalType(IntEnum):
 
     branch_from = 0
     """
-    Measuring the from-terminal between a branch and a node
+    Measuring the from-terminal between a branch (except link) and a node
     """
     branch_to = 1
     """
-    Measuring the to-terminal between a branch and a node
+    Measuring the to-terminal between a branch (except link) and a node
     """
     source = 2
     """