In myenergi installations, Current Transformers (CTs) are vital for monitoring electrical currents at key points, such as the grid connection, solar or wind inverter, or a static battery system. Among these, the installation of a Grid CT sensor is imperative for safety and system efficiency. Fitting the Grid CT is not optional, it is essential for enabling the ECO modes and ensuring the overall safety and functionality of the system.
Additionally, without a Grid CT, any smart features of the zappi will not function as expected, and myenergi is not accountable for any incorrect installation of the product outside of our provided installation instructions.
Importance of the Grid CT for Safety
The Grid CT sensor must be installed at the grid connection point. This ensures that the system accurately monitors the flow of electricity, both imported and exported, and prevents dangerous overloads that could trip the supply or cause a fuse to blow. Without the Grid CT, critical safety features like load balancing and Grid Limit settings cannot function correctly, which could result in serious electrical hazards.
Safety Notice
The Grid CT must be connected to the master device in the system, which typically manages the overall energy distribution and monitoring which allows for:
- Accurate capture of readings
- Safe and efficient operation of the myenergi system
Guidelines for Installing the Grid CT Sensor
The Grid CT sensor, provided with myenergi devices, needs to be correctly installed around either the Live or Neutral meter tail of the electricity supply meter. The correct placement and orientation of this sensor are crucial for ensuring accurate monitoring and maintaining safety:
- Device Compatibility
The Grid CT sensor can be connected to any myenergi device with a CT input, such as the eddi or zappi (for wired sensors) or the harvi (for wireless sensors). - Positioning
If there are no Henley blocks upstream, the sensor should be installed either within the consumer unit—provided a reliable and secure location is available with minimal risk of unauthorised movement—or, if you are unsure about existing cable splits or the presence of Henley blocks, it should be installed at the meter position as illustrated in the installation manuals. - One CT per Phase
Only one Grid CT should be installed per phase in the entire installation. Additional CTs can be used for other purposes, but there should only be one at the grid connection point to avoid conflicts and ensure accurate monitoring. - Cable Selection
The CT sensor should be installed on either the Live or Neutral cable. If placed on the Live cable, the arrow on the sensor must point towards the consumer unit (indicating the direction of grid import). If on the Neutral cable, the arrow should be reversed. - Secure Fitting
The CT sensor must be fully closed and securely clicked shut to ensure it functions properly. - Wiring
Ensure the CT sensor is wired correctly, with the black wire connected to the negative terminal (–) and the red wire to the positive terminal (+). Incorrect wiring can lead to swapped import and export readings, potentially compromising the safety of the system.
Important: harvi CT current limit
If you use a harvi on a supply higher than 65 A, myenergi products will treat 65 A as the maximum fuse limit. This is because harvi is only capable of reading up to 65 A.
If you want to use the full rating of an 80 A or 100 A supply, a grid CT must be hard-wired into a zappi, eddi, or libbi within the same myenergi ecosystem.
CTs and Load Balancing for Safe Operation
Beyond safety, CTs are also crucial for managing the current drawn by myenergi devices, preventing circuit overloads through load balancing or load curtailment. By setting a Grid Limit, users can define the maximum current that can be drawn from the grid connection, ensuring that devices like the zappi adjust their current draw to avoid exceeding this limit.
For example, in a property with a grid supply limit of 65 A, where multiple appliances are drawing 12 kW (52 A), attempting to charge an electric vehicle in FAST mode could cause the total consumption to exceed the grid limit. This could trip the supply or blow a fuse. However, by setting a Grid Limit of 60 A, the zappi would automatically reduce its charging current to 8 A (approximately 1.8 kW), preventing the grid supply from being overloaded.
IMPORTANT: Proper installation and configuration of the Grid CT are essential for anyone looking to achieve optimal performance and safe energy management with their myenergi devices.
The installation of a Grid CT sensor is a critical safety requirement in any myenergi system. It ensures accurate monitoring of electrical currents, enables essential safety features like load balancing, and helps maintain the overall efficiency and safety of the installation.