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-324, Miniature Ferro-magnetic Metal Detection Sensor

  • Drawing of FM-324 Ferro-Magnetic Detection Sensor


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



Miniature Size. 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. Any Ferro-magnetic material is all this is required to operate the sensor from the actuating side as shown in the sketch, and a permanent magnet is not required. The actuating distance may vary depending on the thickness and size of the ferro-magnetic material. All sensors are tested 100% for actuating distance.

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-324-(Cable Length)-(Cable Termination Code)

Cable Termination CodeTermination Type
SStripped to 5.0 mm
TStripped and Tinned

FM-324-250-T Denotes FM-324 Sensor having 250 mm cable length with Tinned lead ends.

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

Dropping Reed switch Reed Switch Handling Reed Switches, Reed Sensor and Magnet Sensors are sensitive devices that easily develop micro cracks in the glass Continue reading ->

Aug 31, 2020

Ferro-magnetic parts

Ferromagnetic parts Reed Switches use an alloy of Nickel and Iron with a few other elements that make the alloy Ferro-magnetic and having a low Remanence. Continue reading ->

Sep 4, 2019

Cable Handling

Twisting cables nearer to housing Magnet Sensor Cable Handling When using Reed Switches soldered to cables, or when using off the shelf Magnet Sensors with cables, some Continue reading ->

Sep 4, 2019

Reed Contact Protection Circuits

Inductive Load Protection Circuit It is assumed that the ideal reed switch load is a Resistive Load, but it is almost impossible to reduce any load to purely resistive. Continue reading ->

Aug 31, 2020


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.

Magnet Sensors for Door and window Security

Reed switches in window security Door/Window Security Home and Workspace security is paramount and most newly constructed spaces integrate security products during Continue reading ->

Nov 6, 2020

FM-324 Miniature Ferro-magnetic Detection Sensors
FM-324 Ferro-magnetic Sensors: 5 mm slots for screw mounting, 10W line voltage, omnipolar, complete data sheet and technical specifications.
Brand: RRE
Manufacturer: Reed Relays and Electronics
Model: FM-324
6 based on 4.1 reviews