Two Paths to Battery-Free Operation
The elimination of batteries from wireless grid sensors requires harvesting ambient energy from the high-voltage environment. Two distinct energy harvesting mechanisms have been developed by Sichuan Yachen Electric for the Qingdao Britop monitoring product line: electric field spatial energy harvesting and current transformer induction. Each mechanism has specific advantages that make it optimal for different application scenarios.
Electric Field Energy Harvesting
Electric field harvesting exploits the potential difference that exists between a conductor at high voltage and the surrounding grounded structures. A sensing electrode placed within this field experiences a displacement current proportional to the voltage, the electrode area, and the capacitive coupling to surrounding grounded surfaces. At 10kV operating voltage, the available power from a practical electrode geometry is in the range of tens to hundreds of microwatts — sufficient to operate a temperature sensor, microcontroller, and intermittent radio transmitter.
The key advantage of electric field harvesting is its independence from load current: the sensor operates whenever the circuit is energized, regardless of whether current is flowing. This makes it ideal for lightly loaded circuits such as backup feeders, for voltage measurement applications, and for any scenario where the circuit may be energized but unloaded for extended periods. The SCYC-CW30 sensor uses this method, integrating the harvesting electrode into the insulating plug.
Current Induction Energy Harvesting
Current induction harvesting uses a split-core current transformer clamped around the conductor. The alternating magnetic field generated by load current induces a voltage in the CT secondary, which is rectified and regulated to power the sensor electronics. Available power increases with load current, typically providing adequate power above 3A — a threshold easily met by most distribution feeders during normal operation.
CT induction is independent of operating voltage, making it suitable for all voltage classes from low voltage to transmission level. The SCYC-PWTM2304 uses this approach with a split-core design that enables installation without disconnecting the conductor.
Choosing the Right Technology
For RMU cable terminations operating at 10kV and above, electric field harvesting (SCYC-CW30) is preferred because cable termination geometry naturally places the sensor in a strong electric field region and the integrated insulating plug design is elegant. For busbar joints at lower voltages or where the sensor cannot be positioned in the optimal field region, CT induction (SCYC-PWTM2304) provides more reliable power. Many utilities deploy both sensor types within the same substation, selecting the optimal harvesting technology for each measurement location based on voltage level, load profile, and mechanical installation constraints.
Related Products from Qingdao Britop
- SCYC-CW30 Electric Field Harvesting Temperature Sensor
- SCYC-PWTM2304 CT Induction Temperature Sensor
- Power Grid Monitoring Products
Related Products:
– GIS Partial Discharge Online Monitoring: UHF, Acoustic, and HFCT Sensing Technologies for Gas-Insulated Substation Reliability
– Transformer Core Grounding Current: Why Online Monitoring Is Essential
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