All of our Reed Switches are 100 % tested in our Standard Test Coils and measured in ampere-turns (AT). Simply stated, we have coils wound in a specific coil form, with a given number of turns. We supply a ramp of current to the coil. When the contacts close, we calculate the number of turns of the coil, times the current flowing when the contacts actually closed, to give us the Pull-in AT for that Reed Switch. Correspondingly, in measuring the point of opening of the contacts, also in AT, we similarly measure the current flowing in the coil at the point of opening and calculate it.
Care must be taken when buying Reed Switches or Reed Sensors from vendors other than Standex Electronics. There is no standardized test coil. All companies have their own test coils and therefore their own AT ranges specific to their test coils.
In this section we describe our test coils so that comparisons can be made to other manufacturers test coils and AT ranges. It is also very important to note that the AT measurements refer to uncut, unbent Reed Switches. Bending and/or cutting the Reed Switches will dramatically alter its opening and closing AT points. When we know the final cut and bending of a Reed Switch or Reed Sensor we typically supply that modified value.
Reed Switch Test Data.pdf