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82 lines
2.9 KiB
ReStructuredText
CT Clamp Current Sensor
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=======================
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.. seo::
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:description: Instructions for setting up ct clamp sensors.
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:image: ct_clamp.jpg
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The Current Transformer Clamp (``ct_clamp``) sensor allows you to hook up a CT Clamp to an analog
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voltage sensor (like the :doc:`ADC sensor <adc>`) and convert the readings to measured single phase AC current.
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First, you need to set up a voltage sensor source (:doc:`ADC sensor <adc>`, but for example also
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:doc:`ADS1115 <ads1115>`) and pass it to the CT clamp sensor with the ``sensor`` option.
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Please also see `this guide <https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/introduction>`__
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as an introduction to the working principle of CT clamp sensors and how to hook them up to your device.
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.. figure:: images/ct_clamp-ui.png
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:align: center
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:width: 80.0%
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.. code-block:: yaml
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# Example configuration entry
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sensor:
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- platform: ct_clamp
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sensor: adc_sensor
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name: "Measured Current"
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update_interval: 60s
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# Example source sensor
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- platform: adc
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pin: A0
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id: adc_sensor
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Configuration variables:
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------------------------
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- **sensor** (**Required**, :ref:`config-id`): The source sensor to measure voltage values from.
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- **sample_duration** (*Optional*, :ref:`config-time`): The time duration to sample the current clamp
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with. Higher values can increase accuracy. Defaults to ``200ms`` which would be 10 whole cycles on a 50Hz system.
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- **update_interval** (*Optional*, :ref:`config-time`): The interval
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to check the sensor. Defaults to ``60s``. The **update_interval** for ``ct_clamp`` has to be greater than **sample_duration**.
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- All other options from :ref:`Sensor <config-sensor>`.
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Calibration
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-----------
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This sensor needs calibration to show correct values, for this you can use the
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:ref:`calibrate_linear <sensor-filter-calibrate_linear>` sensor filter. First, hook up a known
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current load like a lamp that uses a known amount of current.
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Then switch it on and see what value the CT clamp sensor reports. For example in the configuration below
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a 4.0 A device is showing a value of 0.1333 in the logs. Now go into your configuration file
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.. code-block:: yaml
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# Example configuration entry
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sensor:
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- platform: ct_clamp
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sensor: adc_sensor
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name: "Measured Current"
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update_interval: 60s
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filters:
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- calibrate_linear:
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# Measured value of 0 maps to 0A
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- 0 -> 0
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# Known load: 4.0A
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# Value shown in logs: 0.1333A
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- 0.1333 -> 4.0
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Recompile and upload, now your CT clamp sensor is calibrated!
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See Also
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--------
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- `EMonLib <https://github.com/openenergymonitor/EmonLib>`__
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- `CT Clamp Guide <https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/introduction>`__
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- :doc:`adc`
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- :doc:`ads1115`
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- :apiref:`sensor/ct_clamp_sensor.h`
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- :ghedit:`Edit`
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