Reed switches whether they are used in sensors or relays all will be asked to switch some load. Generally there are two aspects to this load.
- Its steady state load
- Is the actual switching taking place during the first 50 nanoseconds. This is also called the signature of the load.
This signature takes into consideration not only the steady state load but also any transient voltages or current that may be present during the first 50 nanoseconds. These transients may be from stray capacitance, inductance in the line and/or common mode voltages. From a reed switch designer standpoint, the signature is all there is. The most important time during the switching of a load is that first 50 nanoseconds. That is when all the damage to the contacts with occur if you are switching the contacts ‘hot’. If a customer is having a problem with early failures, this is the first place to look. Equally important and not to be overlooked is what voltage and current is actually being broken when the contacts open. Any healthy voltage and/or current present will chew up the contacts rapidly leading to sticking reed contacts.