Radio frequency alternating current meter with a standby loss of only 0.5 watts. A modular device for mounting on DIN-EN 60715 TH35 mounting rails. 1 module unit = 18 mm wide, 58 mm deep. This alternating current meter measures active energy based on the current flowing between the input and output and transmits the consumption and meter reading to the Eltako radio network. Accuracy class B (1%). Evaluation on a computer with the building radio visualization and control software GFVS or with the energy consumption display FEA65D. GFVS-Energy supports up to 100 transmission modules, GFVS 4.0 supports up to 250 transmission modules. The self-consumption of a maximum of 0.5 watts active power is not measured and not displayed. Like all meters without MID conformity declaration in Europe, they are not approved for monetary electricity billing. One phase conductor with a current of up to 65 A can be connected. If a load of more than 50% is expected, a ventilation distance of 1/2 module unit must be maintained from adjacent mounted devices. If necessary, use the spacer DS12. The starting current is 40 mA. The consumption is stored non-volatile and is immediately available after a power failure. Radio telegrams: A telegram is sent within 60 seconds if the power changes by at least 10 percent. A change in meter reading is sent immediately. A total telegram with meter reading and power is sent every 10 minutes. When the supply voltage is switched on, a learning telegram is automatically sent so that the corresponding energy consumption display can be learned. If the L-input and L-output are swapped during connection, an HT/NT switching telegram is sent every 20 seconds to indicate the connection error.