FEATURE SWITCHES & RELAYS A GOOD HARVEST FOR SWITCHES


Jana Pilhofer, junior product manager, Energy harvesting products, ZF Switches & Sensors, explains how energy harvesting switches offer a maintenance-free, simple to install and relocate, long lifetime alternative to conventional electromechanical types


I


n our increasingly connected world, there is growing demand for simple to


use, flexible data transmission and low energy consumption. ZF Switches & Sensors has developed a wireless and batteryless Energy Harvesting Technology which can provide cost effective switching solutions in a range of environments and applications. Applications areas include smart home, office, medical, industrial systems and building automation. Designed for global use and compatible


with multiple wireless protocols, the technology enables ZF to offer an alternative to wired or battery-powered switching solutions. As there is no need to change or dispose of batteries, the solution is both maintenance-free and environmentally friendly. With no cabling to install, Energy


harvesting wireless switches can be mounted on almost any surface and are simple to relocate if required. The function of the switch may also be changed by reconfiguring the wireless output signal. The ZF Energy Harvesting product


portfolio includes a packaged hand operated rocker for applications including electrical appliances and an industrial snap-action switch for mechanical actuation by a machine or use as a proximity switch. A stand-alone generator for OEM design is also available. Receivers to work with ZF wireless switch


modules are available as either a self- contained packaged module suitable for DIN-Rail or wall-mounting with multiple output options (i.e. RS232, TTL), or as a hand soldered or SMD assembled “RF stamp” complete with wire antenna for OEM designs. The popular KNX intelligent building


control system for residential and commercial environments is also supported. ZF offers the sole KNX-RF Energy Harvesting pushbutton module as well as a KNX pairing adapter and matching receiver (media coupler). Activating any switch variant provides


wireless data transfer, eliminating the need for expensive and complex cabling, and increasing flexibility of use. Flexible pairing allows the operation of several switches with one receiver and vice-versa. Each switch has a “Unique ID” providing


24 MAY 2017 | ELECTRONICS


clear identification when operating several switches at once. Up to three “telegrams” are sent per actuation, with pseudo- random timing to assure robust data transmission.


GENERATOR TECHNOLOGY OVERVIEW Based on the inductive principle, the direction change of the magnetic field in an inductive magnetic circuit transforms mechanical energy into the electrical energy required to send an RF signal from the patented Energy Harvesting Generator. This technology is then packaged and assembled, together with an operating mechanism, resulting in the raw


Generator technology is based on the inductive principle


ZF’s Energy Harvesting


Generator (above) and Energy Harvesting Generator with wireless


transmission electronics (left)


form of the standard product – the generator.


The Energy Harvesting


Generator is available separately for OEM applications with or without the RF


electronics and


integrated into ZF’s Energy Harvesting switch modules. It consists of a coil and


a magnet block which is actuated when a


Tables below show overview of the


Generator (top) and RF Generator Module


mechanical force acts vertically on the end of the generator’s lever. A patented mechanism causes the magnetic block to move down abruptly (switching) and a positive pulse is created by reversing the polarity of the coil. When the lever is released, the system returns to the initial position (resetting) by means of the mechanism and a negative pulse is created. The energy produced is used to transmit a wireless signal indicating operation of the switch. The initial energy pulse created provides the harvested electrical power output, which is then transformed and averaged over time by internal energy management components to create the supply voltage for the wireless transmitter. The small size, high efficiency and long life expectancy (up to 1,000,000 cycles) makes the product, in either form factor, suitable for installation in tight spaces without having to take in to consideration routine maintenance. In addition to pre-assembled switch


FEATURE SPECIFICATION


Size 20.1x7.3x14.3mm Energy Output Lifetime


Typically 0.33mJ (per half cycle) up to 1,000,000 switching cycles


Actuation Force 13 N (momentary) 5N (latching, lever length depend.)


Temperature Range -40˚C to 85˚C Frequency Bands 868.3 MHz, 915.0 MHz Protocol


ZF Proprietary RF Distance Protection


up to 300mm (open space) up to 30m (in building) IP40


modules for general HMI purposes, two switch modules have been designed specifically for building automation, a 1- way and a 2-way pushbutton. Key benefits of using energy harvesting


powered switching systems include; wireless signal output, no power source or battery required, energy saving, low system installation and maintenance costs, flexible system design, long lifetime, simple installation, maintenance free and eco-friendly. Typical applications include; smart home


FEATURE SPECIFICATION


Design Universally adaptable customer-specific parts


Lifetime exceeds 100,000 switching cycles


Frequency bands 868.3 MHz, 915.0 MHz, 2.4 Ghz Protocol


Various including ZF Proprietary, ENOcean, ZigBee...


light switch or handheld controller, RF enabled bulb control, wall socket outlet or adapter control, window handle linked to room thermostat, building and office automation, industrial control limit switch, control pedal, emergency stop actuator, machine remote control.


ZF Switches & Sensors www.switches-sensors.zf.com T: 01582 814006


/ ELECTRONICS


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