Detachable level probes with integrated lightning protection : well protected against overvoltage

The detachable level probe LMK 808 with a robust, capacitive ceramic sensor and a pressure tightness of up to 20bar is one example of this.

It also has two-stage overvoltage protection which protects the sensor signal and signal processing and transmission. Whilst the primary protection ensures that the overvoltage is limited to 90 V and a pulse current up to 8,000 A (8 kA) is dissipated, the subsequent secondary protection reduces the voltage to 36V, has a bipolar affect and can record a pulse power of 1,500W. (To document the performance of the measures, overvoltage tests were carried out in an accredited test laboratory pursuant to standard EN 61000-4-5. The results show that standard test pulses with a severity of 4,000V (4 kV) do not cause any damage.)

On the other hand, the probe head on the level probe can be detached from the cable part. This means that the cable that was laid at great expense does not have to be removed from cable ducts or protective pipes if it is damaged or needs to be serviced. Instead, simply unscrew the probe head, clean it and screw it back on, or replace it with the spare part. The effort required for this takes just a few minutes, meaning that the level probe can quickly be put back into operation and downtimes are kept low.