Energy and efficiency

Energy and efficiency

In this paper we will focus on a basic application for residential automation: load control. Born as a traditional stand-alone device in the first 2000s, load control has evolved into a main integrated feature of a home automation system. Load control is a feature preventing unnecessary overload interventions of the electric meter, often installed on the outside and generally far from the house. To achieve this function, three Ekinex products are used: a three-phase energy meter EK-ME1-80T with KNX interface EK-MC1-TP, a Codesys PLC with KNX interface EK-IA1-TP and an eight outputs actuator EK-FE1-TP properly interfaced with auxiliary relays.

Care for consumptions

The wiring diagram to consider is the one attached. The system, controlled by a PLC properly programmed using one of the 5 available Codesys languages, can manage up to 8 loads, by reading the absorbed power value (through the energy meter) and command the output actuator. Inside the PLC program, each load is assigned to a priority, which determines the on-off switching order. The system keeps constantly under control the total absorbed active power and, if that value reaches a programmed threshold, starts to sequentially disconnect all loads until the total power falls under a desired threshold. When the electric consumption returns inside its normal range, the PLC program checks if the managed power is supported by the system and if it is possible to reconnect the electric loads, this time with a reversed priority. 

The state of the art dictates to integrate devices capable of forcing the operation independently from the control itself, such as an 8-channel pushbutton, in order to avoid the load disconnection if retained under control by the user. Devices capable of displaying the controlled loads’ status and editing the intervention thresholds can be integrated, such as local (touch) or network supervision systems. 

Limitless control

The above-described system allows controlling several outputs, being completely programmable by the PLC, thus making load control very easy. This feature can be useful both in three-phase and single-phase systems, using the proper meters, and also for programmed overnight disconnection, in order to avoid some appliance to remain unnecessary active, or paired to a “Going out” scene, in order to shutdown decoders, hi-fi stereos, SmartTVs, etc.