Reed Relays and
Electronics India Limited
Manufacturer of Reed Switches, Reed Sensors and Reed-based products
Reed Relays and Electronics India Limited Incorporated in 1971

FM-328, Standard Ferro-magnetic Metal Detection Sensor

  • Drawing of FM-328 Ferro-Magnetic Metal Sensor


Actuates with Any Ferrous Metal. 10W Contact Rating. Normally Open contact. Sputtered Ruthenium Contact. Easy Screw Mounting.



Does not require power for operation. RoHS Compliant. Not ESD Sensitive. Various Cables and Connectors Available.


This screw mountable sensor can be mounted with M3 screws and can switch moderate loads of 10W. It can be actuated on the actuating side as shown below, by any Ferro-magnetic material that is longer than the length of the sensor. Actuation distance is 3.0 – 8.0 mm and Release distance is 4.0 – 10.0 mm. Unlike other standard Magnet Sensors, an actuating magnet is not require.  All sensors are tested 100% for actuating distance before packing. Click to download this product data sheet as a PDF.

Operate Distancemm3.0 – 8.0
Release Distancemm4.0 – 10.0


Contact FormA
Contact Rating (max)W/VA10.0
Switching Current (max)A0.5
Carry Current (max)A0.75
DC Switching Voltage (max)VDC100
Breakdown Voltage (min)VDC150
Contact Resistance (max)150
Insulation Resistance (min)Ω109
Capacitance (typ)pF0.2


Operate Time (max)ms0.35
Bounce Time (max)ms0.30
Release Time (max)ms0.15
Resonance Frequency (typ)Hz>2000
Operating Frequency (max)Hz500
Operating Temperature Range°C-40 to +70
Shock Resistance (½Sin wave for 11ms)G30
Vibration Resistance (10-2000 Hz)G20

Ordering Code

FM-328-(Cable Length)-(Cable Termination Code)

Cable Termination CodeTermination Type
SStripped to 5.0 mm
TStripped and Tinned

FM-328-500-S Denotes FM-328 Sensor having 500 mm cable length with leads Stripped to 5 mm.

Other Special Configurations: Dynamic Contact Resistance Limit, Special Release AT Limits.

Usage Notes

Here are some of the recommended usage notes to ensure maximum durability of this product. The complete usage notes are available here.

Product Handling

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Although we can never restrict the use of a reed sensor to a particular field, the following is a list of some of the applications that the FM-328 Ferrous Metal Detection Sensor is known to perform well.

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FM-328 Ferro-magnetic Detection Sensors
FM-328 Ferro-magnetic Sensors: 8 mm slots for screw mounting, 10W line voltage, omnipolar, complete data sheet and technical specifications.
Brand: RRE
Manufacturer: Reed Relays and Electronics
Model: FM-328
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