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
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Reed Switch Test Coils

Using a test coil is one of the most accurate ways of measuring a reed switch or a reed sensor’s sensitivity. The number of turns in the test coil multiplied by the current at which the switch closed gives the Operate Ampere Turn, which is a direct measure of sensitivity. Care should be taken to see the the test 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 to the test coil. No Ferro-magnetic crocodile clips, connectors or mounting parts should be nearby.

Cylindrical Test Coils

drawing_coil_round
All dimensions in mm

Test coil 001 002 003 005
A 53.3 21.0 12.0 19.0
B 50.8 19.0 10.0 15.0
C 7.6 4.3 3.3 3.7
D 5.6 3.4 2.3 2.9
E 14.1 7.7 11.0 11.0
Wire Diameter (mm) 0.090 0.050 0.060 0.071
Turns 10000 5000 5000 5000
Resistance (Ω) 845 740 600 450

Rectangular Test Coils

drawing_coil_rect
All dimensions in mm

Test coil TCP 3001 TCP 3002 TCP 3003 TCP 3004
A 13.5 23.3 42.5 42.5
B 7.0 19.7 36.5 36.5
C 8.0 6.8 14.8 15.8
D 6.0 6.2 13.8 13.8
E 14.0 14.8 25.0 25.0
F 18.0 20.6 28.6 35.6
G 12.0 12.2 14.6 22.8
H 10.0 11.6 13.6 20.8
Wire Diameter (mm) 0.050 0.080 0.150 0.150
Turns 5000 10000 5000 5000
Resistance (Ω) 2000 1900 290 440