Location in the grid
The DigitalTF transmitter is placed in the MV/LV distribution station (red arrow). In modern TN-S grids it is placed in the LV Neutral line, directly after the coupling with Protective Earth (PE). A 630 KVA transmitter for 20 bits/sec has a Bill Of Materials of approx 120 euros.
In a TN-C grid the transmitter is placed in all 3 phase lines. In that case the BOM is slightly higher because the coupler has to increase in size to accommodate the L1, L2 and L3 phase lines.
The transmitter is fed from one of the phases L1, L2 or L3, from which the 150/180 or 300/360Hz timing of the carrier is derived. The transmitter uses a proprietary Phase Locked Loop to generate extremely accurate timing
The microprocessor inside the transmitter can be interfaced in various ways to your cellular (3G, LTE, LoRa etc) modem. For trials we have a transmitter available that can be interfaced to relays via 4 dry contacts.
The carrier is generated using a full bridge to feed the toroid coupler transformer,
employing MOSFET switches at relatively low power.
DigitalTF transmits 24/7, such that these switches are operated continuously.
The carrier is coupled to the mains wiring by a toroid transformer of which the secondary winding is a single winding, a single feed-through wire.
A complete transmitter and coupler
In all, this is a complete transmitter including toroid coupler! The electronics is suitable for 630KVA, but the coupler has been replaced by a small unit to reveal the electronics.
This box will be the only hardware in a DigitalTF enabled LV grid, as all reception is integrated into microprocessor-based devices. We have prototype transmitters available for trials.