Digital Ring Detectors

As single stand-alone components, our ring sensors are also used in many other ways. They can be used , for example, for counting parts, i.e., screws or bolts, as discharge monitoring devices for stampings, for detecting broken wires. The output signals of ring sensors can be used for controlling, signaling or evaluating events in many different industrial processes. We offer a wide range of ring sensors which differ in design, sensitivity and/or kind of output signals.

Function and Limitations

The MESEP® RG digital ring detector works according to a balanced measuring principle which is ideally suited for detecting all kinds of metal inside products within non-metallic packaging. This balanced measuring principle is explained below.

A typical ring detector includes the following components:

  • A Transmitter Coil - for producing a high frequency magnetic field.
  • Two Receiver Coils - that receive signals generated by the magnetic field.

Once the ring detector is switched on, the magnetic field capacity of the transmitter coil is adjusted so that both receiver coils receive the same identical signal. This balances the system as metal moves through the magnetic field of the metal separator. The modification of the magnetic field changes the current in the receiver coil which becomes unbalanced and is called an electromagnetic process.

The degree of change of the magnetic field is the direct result of the changes in the magnetic and electrical properties of the metallic particle. While bigger metallic particles generate greater currents than smaller particles, magnetic metals like steel cause greater currents than non-magnetic metals like aluminum. The modified current is measured, processed and evaluated by the metal detector and its software.

Metal Free Zones (MFZ)

The active magnetic field surrounds the complete ring housing. That means the magnetic field is not limited to the length of metal housing. In front and behind the free ring opening bigger metal parts will also be detected. To assemble the ring detector properly, the user must prevent that conductable part of the metal from entering certain areas called metal free zones (MFZ). In this areas plastic parts or other non-onductable adapters are allowed. This explains why the Protection Tube Material inside the ring detector is usually made of plastic.

It is important to know how large the metal free zone should be. Metal free zones for moving metal parts are also often larger than metal free zones for nonmetallic moving parts. Problems can arise if the user installs a metal shaft, a metal flap, a rotating metal part or any other static metal construction inside a metal free zone. The ring detector will generate a false report of metal and the user will be tempted to lower sensitivity levels to avoid any false reports. Unfortunately, when the sensitivity level is lowered to compensate for these false reports, some metals can make it through undetected. Correct sizes of the metal free areas can be found in the table below.

Model Name MESEP RG 50 Digital MESEP RG 70 Digital
Mounting not flushing not flushing

Main Connections [no product effect assumed] -
Sensitivity at the edge of detector [Fe/NE/VA-bullet in mm] app. 0.5/1.0/1.2 app. 0.7/1.2/1.5
Sensitivity adjustable by Multifunction panel
Mode of operation of evaluation electronics digital
Mode of operation of ring detector Transmitter - Receiver
Operating voltage Ub 85-274 V/47-440 Hz or 110-340 V DC

Inputs Test button

Transistor output metal detection 24 V/20 mA
Power supply for periphery 24 V/20 mA
Metal detection/self-monitoring 2* 250 V/5A
Pulse duration adjustable up to max. 2 sec per metal detection
Ambient temperature 0-60° C
Protection class of coil/electronics IP 67/IP 50
Material of coil fomer Tecamid GF30
Housing Material of ring detector Aluminum casting
Free diameter of the detection coil 55 mm 75 mm
3 m Connecting cable L1/N/PE* 1.5 mm2
Advice: external electronic box with 3 meter cable connection between coil and box
Metal free zone for flexible metals 75 mm above and under the detector 100 mm above and under the detector
Metal free zone for non flexible metals 50 mm above and under the detector 70 mm above and under the detector

Model: MESEP RG 50 Digital

Model: MESEP RG 70 Digital

Contact us today: - Tel: 973.227.0700

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Plastic Process Equipment

Plastic Process Equipment

23 Spielman Road, Fairfield, New Jersey, USA, 07004-6155
Tel: 973.227.0700 ~ Fax: 973.227.7307 ~ Email: