These devices can also be configured in multiple channels. So you often see a DC rating of 24VDC or 120VAC due to this behavior. Four types of optoisolator components (from left to right): Schmitt buffer, triac, phototransistor, and SCR.
there are several different derating factors, but inductive loads are severe.Īnd DC use is usually more aggressive since metal migration only in one direction from point-to-point. I generally don't bother with anything under a 10amp rated relay. There are other things to do enhance the longevity of the points, but those really should come into consideration after you apply a derating according to the type of load. The opto-isolator can deal with differential voltages of up to 4000V. At the output side, it can drive loads up to 70V. Read the derating document attached, that is the guideline. A small, cheap (4), common optoisolator like the ILD205T comes in an SMD SOIC-8 package, contains two channels, require just 10mA (and can tolerate up to 100mA) to turn the embedded LED on at 6V. In other words, for 1.8 amps of inductive load, you need a 4.5 amp or better rated relay. You may not like thiis answer, but the 'derating' factor for inductive loads which is normally applied to limit the current capacity of the relay to 40% of the advertised rating (motors derate down to 20%!).
Is there something I can do to alleviate the contact arcing? The load solenoids do have snubber (free-wheel) diodes, BTW. Going through these relays at an alarming rate but they are a very small package that I can't simply replace due to limited space. We are right at 1.8A and switching at approximately every 5 seconds. These are name-brand relays (Phoenix Contact) and rated at 2A switching of an inductive 24v DC load (solenoid coil).
0 kommentar(er)
