Weighing Principle (EMFR) and Active Vibration Compensation (AVC)

The principle of electro-magnetic force restoration (EMFR) is a combination of electrical and mechanical components. The design of EMFR Weigh Cells is based on a balance mechanism. It consists of a position indicator, a controller and an electro-magnetic drive (coil and permanent magnet). In its functionality, the Weigh Cell can be compared to a simple beam balance.

If a weight is placed on one side of the beam, the opposite side of the weighing beam attempts to move out of the magnet's magnetic field. The position indicator detects this deviation and the amount of current required for balancing the beam and ensuring that no position change can occur is transmitted through the coil.

As the current is proportional to the weight and can be measured via a resistor, it can be converted into a digital signal which is used for further processing.

Using this operating principle of electro-magnetic force restoration (EMFR), it is possible with such a Weigh Cell to achieve high resolutions and good repeatability together with the shortest measuring times. We are continuously enhancing the magnet system, the electronics with scanning circuits, controller boards and measured value determination, as well as specific communication interfaces.

The result is a Weigh Cell that enjoys an excellent reputation throughout the world under the slogan "A Weigh Cell is better than a load cell". However, this is still not everything that makes our Weigh Cells so unique: we also offer you the option of AVC (Active Vibration Compensation) technology.

AVC White Paper

EMFR Weigh Cell provides very fast and highly precise measured results

The key benefit of a Weigh Cell with Electro-Magnetic Force Restoration (EMFR) from Wipotec is its extremely short settling time. Compared to the weighing principle with strain gauges, it provides very precise weights significantly faster and is also straightforward, space- and cost-saving to integrate into existing systems. Wipotec checkweighers with EMFR Weigh Cells give that lead in the blink of an eye. Depending on the series, their measuring range is from 1 microgram to 120 kilograms.

Principle of operation of EMFR

The basic principle of this weighing can be compared to a simple beam balance. The load to be determined acts on the end of one of the two lever arms. This causes the coil fastened to the opposite end to want to move out of the magnetic field.

An optical position detection system perceives any minimal deflection and signals it to a high-precision position regulator that adjusts the coil current so that the weighing beam remains in equilibrium. This current is measured using a measuring resistor and further processed in a microprocessor system for direct output as a digital weight.