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

Test Coils for Reed Switches and Reed Sensors

  • Cylindrical Test Coils Drawing
  • Rectangular Test Coils Drawing


Wound on Wooden Bobbin. Enamelled Copper Windings. Uniform Layering. Accurate Coil resistance.



Withstands 80°C. Economical Repeatable Measurements. Suitable for 4-Terminal Kelvin Circuits. Suitable for Reed Switch Life Tests.


Using Test Coils is one of the most accurate ways of measuring various parameters of a Reed Switch, Reed Sensor or Magnet Sensor, such as Operate AT, Release AT, Contact Resistance and other test parameters. The number of turns in the coil multiplied by the current at which the switch closed gives the Operate Ampere Turn, which is a direct measure of its magnetic sensitivity.

Care should be taken to see the the coil is always used vertically so that the earth’s magnetic field does not affect the measurement, and that the reed switch or reed sensor under measurement is always centered inside. No Ferro-magnetic crocodile clips, connectors or mounting parts should be nearby as this will cause measurement errors. It is always more accurate to use Four-terminal Kelvin measurements.

We offer customers a range of Test Coils, in cylindrical and rectangular shapes, to suit the measurement of our products. The Test Coil specifications are listed below.

Cylincdrical Test Coil Dimensions

Test Coil Code 001002003005
Bobbin Length (BL)mm53.521.012.019.0
Winding Length (WL)mm50.819.010.015.0
Flange Outer Diameter (FOD)mm14.17.711.011.0
Flange Inner Diameter (FID)mm5.
Copper Wire Diametermm0.0900.0500.0600.071
Coil ResistanceΩ845740600450

Rectangular Test Coil Dimensions

Test Coil Code 3001300230033004
Bobbin Length (BL)mm13.523.342.542.5
Winding Length (WL)mm7.019.736.536.5
Flange Outer Length (FOL)mm18.020.628.635.6
Flange Inner Length (FIL)mm10.011.613.620.8
Flange Outer Width (FOW)mm14.014.825.025.0
Flange Inner Width (FIW)mm6.06.213.813.8
Copper Wire Diametermm0.
Coil ResistanceΩ20001900290440

Reed Switch Life Tests

Reed switch wave form Information on life testing reed switches. A life test is a destructive test conducted...Continue reading ->

Reed Switch Test Procedure

Reed Switch testing circuit Sample circuits for measurement of ampere turn values and static contact resistance of reed...Continue reading ->
Reed Switch Test Coil
List of standard test coils used to measure reed switch and reed sensor operating parameters.
Brand: RRE
Manufacturer: Reed Relays and Electronics
Model: TCP
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