Utility Meters Use Reed Sensors To Measure Water Flow, Gas and Electricity REED RELAYS REED SENSORS REED SWITCHES Introduction Most households and businesses have meters reading and recording the volume of water used, the volume of gas used and/or the amount of electricity being used. Most of these meters used reed sensors to count and measure the usage for each household. This is done in a power efficient and tamper proof way using reed sensors. Figure 1. MK17-X-3 Sensor physical layout Features • Magnet and Reed Sensor are isolated and have no physical contact by typically having the magnet mounted to a rotating disk, and the Reed Sensor is mounted strategically such that the magnetic field of magnet will be sensed with each rotation of the disk. Figure 2. Paddle rotates magnet which actuates switch contacts. • The reed switch used in the Reed Sensors is hermetically sealed and is therefore not sensitive to its surrounding environment • The magnet is not affected by high and low temperature environments • Tens of millions of reliable operations • Surface mounting and through hole mounting • Contacts dynamically tested Applications • Ideal for sensing the rotation of disks in utility metering requirements • Ideal for applications sensing rotation in a host of different configurations Figure 3. Switch actuation measures flow and sends reading to meter which transmits wirelessly to utility headquarters. Reed Sensors are the Choice for Measuring Utility Usage Power and water utility companies around the world have come to select reed sensors as the technology of choice for determining the usage at each home or workplace. The older mechanical counters were expensive and wrought with breakdown along with faulty counting. They were also subject to the extremes of weather where they could react adversely. Its easy to build in redundancy and make the meters tamper proof using reed sensors as well. Most of the utility meters convert the flow of water, gas, and/or electricity to the movement of a rotating disk. Each rotation is directly equated to a given volume of water or gas. In the case of electricity, each rotation directly equates to a given amount of kilowatt hours usage. Usually a magnet is mounted on this rotating disk. Whenever the disk completes a revolution the reed sensor, which is conveniently mounted on a PCB, is so positioned to sense each revolution of the magnet. MEDER electronic Application MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: [email protected] MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: [email protected] Page 1 of 3 www.meder.com Utility Meters Use Reed Sensors To Measure Water Flow, Gas and Electricity REED RELAYS REED SENSORS REED SWITCHES Specifications Defining the MK06 & MK15 Series Operate specs Min Max Units Must close distance 5 25 mm Must open distance 5 25 mm Hysteresis Load Characteristics Switching voltage Switching current Carry current Contact rating Static Contact resistance Dynamic Dynamic contact resistance Breakdown voltage Operate time Release time Operate Temp MK06 Storage Temp MK06 Operate Temp MK15 Storage Temp MK15 MK15 Typical 50% Min Max Units 200 0.5 1.5 10 150 200 320 -20 -20 -20 -20 0.5 0.1 85 85 130 130 When the reed sensor senses the revolution, it sends a signal back to the electronics which is duly recorded using an electronic counter. In this way the exact volume used is accurately recorded along with accurate recordings of the amount of kilowatt hours of electricity used. Meter readers can then come by or have the usage information sent to them wirelessly. Then of course, the dreaded part for the user occurs where the bill is formulated and sent to the customer. There are other reed sensors used in the same circuitry that are also strategically placed as well. If one tries to stop the reed sensor from sensing each rotation by using a strong external magnet, these other reed sensors will activate triggering an alarm. Because MEDER’s sensors use hermetically sealed reed switches that are further packaged in strong high strength plastic, they can be subject to various environments without any loss of reliability. V Amps Amps Watts mΩ The reed sensor is an excellent choice because it can operate reliably over a wide temperature range, and represents an economical way to carry out the sensing function. MEDER’s sensors are packaged for surface mounting as well as through hole mounting. mΩ Consider some of the below options in surface mount and through hole versions for meter reading or similar applications. V msec msec °C °C °C °C Surface Mount Series Series MK15 MK16 MK17 MK22 MK23MK23-35 MK23MK23-66 MK23MK23-87 Figure 3. MK15 Tape & Reel MK23MK23-90 Dimensions mm W 2.5 H 2.5 L 19.50 W 2.3 H 2.3 L 15.60 W 2.1 H 2.1 L 9.61 W 2.7 H 2.3 L 15.60 W 2.2 H 1.95 L 15.75 W 2.2 H 2.7 L 19.60 W 2.0 H 2.1 L 15.60 W 2.54 H 3.05 L 24.9 Illustration inches 0.098 0.098 0.768 0.091 0.091 0.614 0.083 0.083 0.378 1.060 0.091 0.614 0.087 0.077 0.620 0.087 1.060 0.772 0.079 0.083 0.614 0.100 0.120 0.980 MEDER electronic Application MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: [email protected] MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: [email protected] Page 2 of 3 www.meder.com Utility Meters Use Reed Sensors To Measure Water Flow, Gas and Electricity REED RELAYS REED SENSORS REED SWITCHES Through Hole Series Series MK06MK06-4 MK06MK06-5 MK06MK06-6 MK06MK06-7 Dimensions mm W 3.3 H 3.3 L 12.06 W 2.8 H 3.2 L 14.30 W 3.3 H 4.2 L 17.24 W 3.3 H 4.2 L 19.78 Illustration inches 0.130 0.130 0.475 0.110 0.126 0.563 0.130 0.165 0.679 0.130 0.165 0.779 **Consult the factory for more options not listed above. ** MEDER electronic Application MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: [email protected] MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: [email protected] Page 3 of 3 www.meder.com