Because of their semiconductor technology-based design, SSRs provide a higher degree of reliability, longer life and reduced electromagnetic interference (EMI), as well as faster response times and vibration and shock resistance, when compared to the EMR counterparts. This is due to the fact that SSRs have no mechanical contacts to wear out or arc, which is the primary cause for EMR failure.
A curve without heatsink is given for the SO/SC or SG type of solid state relays. When mounted on the back plate of a cabinet, the relay/plate contact must be correct. An aluminium back plate of 150mm x 150mm x 3 mm corresponds to approximately 4°/W An aluminium back plate of 300mm x 300mm x 3 mm corresponds to approximately 2°/W In all cases, it is recommended to perform a test and measure the heat dissipation. A steel plate will have greater thermal resistance..
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The sensitive element of the magnetic sensor can be a Hall effect cell, a magnetoresistance or a reed switch detecting the presence of a magnetic field, generally a permanent magnet. It detects without contact the position of the magnet and transmits an electrical signal.
Polyamide level sensors can be used in low chlorinated water such as swimming pools but polypropylene sensors are more suitable.
When in the application there is a problem of agitation of the level (wave effect) it is necessary to put the detector in an anti wave system. Generally this system consists of a closed tube which envelops the detector and which is pierced with at least 2 holes (it is necessary to think of the evacuation of the air when the level rises).
The smaller the holes, the greater the difference between the real level and the level inside the tube: it is therefore necessary to find the right compromise: eliminating waves and good level monitoring.
The main advantages are:
- No power supply required. No current consumption in open state with real galvanic isolation and no voltage drop in closed state.
- Works in difficult environments: wide temperature range, insensitive to dust, water projections, ...
- The detection distances can be very large. They will depend mainly on the magnetic sensitivity of the bulb and the power of the magnet as well as the magnetic environment of the couple Reed Switch + Magnet.
- Very economical compared to all other technologies.