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???
03/04/04 17:52
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#65979 - RE: Solenoid operated Pneumatic valves
Responding to: ???'s previous message
Hallo Prahlad,

from mobile welding machines I know, that mechanical contactors are used for controlling protection gas (argon + etc.). Good mechanical contactors have a lifetime of 3 x 10**7 switchings. So, you can estimate how many years your product will work.

On the other hand, solid state contactors are much more elegant, of course. Smaller, quiet, less control power. BUT: Solid state contactors are not fool proof! Most of them are susceptible to fast voltage changes across their contacts. If the voltage across contacts shows a change rate of more than 500V/µsec (this is a typical value), solid state contactor is firing itself! Means, solid state contactor is eroneously turned-on!!
Such seltriggering can occur for instance, if the 100VAC supply has had a momentary power-down and turns-on again very rapidly. So, with solid state contactors you always need to take special care on filtering in order to remove glitches of higher slew rates than 500V/µsec. One very simple methode is to put a capacitor across contacts. But a right line filter will show much better results, of course.

You could experiment with SC862110 from CELDUC, e.g. Is available from RS-components under "231-3566". Control voltage: 5-30DC, Contacts: 24-520VAC (0.1-400Hz), Imax = 25A, dv/dtmax = 500V/µsec.
Makes contact at zero voltage, opens contact at zero current and is fabricated to be used with solenoid valves, beside others, of course.

Kai

List of 23 messages in thread
TopicAuthorDate
Solenoid operated Pneumatic valves            01/01/70 00:00      
   RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
   RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
      RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
   RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
      Solenoid operated Pneumatic valves            01/01/70 00:00      
         RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
   RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
      RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
      RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
         RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
            RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
         RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
   RE: Solenoid operated Pneumatic valves            01/01/70 00:00      
   First Things First            01/01/70 00:00      
      RE: First Things First            01/01/70 00:00      
   PS/2 Keyboard near Welding area.            01/01/70 00:00      
      RE: PS/2 Keyboard near Welding area.            01/01/70 00:00      
      RE: PS/2 Keyboard near Welding area.            01/01/70 00:00      
         RE: PS/2 Keyboard near Welding area.            01/01/70 00:00      
         RE: PS/2 Keyboard near Welding area.            01/01/70 00:00      
            RE: PS/2 Keyboard near Welding area.            01/01/70 00:00      
   RE: Solenoid operated Pneumatic valves            01/01/70 00:00      

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