[GreenKeys] Solid State relays

[Bruce Gentry]

Bruce Gentry wrote:
> Larry Tighe wrote:
>> Howdy Folks,
>>
>> I have a solid state relay, rated at 240 VAC, 20 amps.  It can be 
>> keyed with 6 VDC.  I put the ohm meter (analog) across the AC 
>> terminals and it opens and closes the "switch" with 6 VDC.
>>
>> I tried to key a tty loop with it and it won't close the circuit.  
>> Anyone tried playing with these successfully?  For now, I can't 
>> understand why it would show on an ohmmeter with probably 3 volts 
>> from the meter and then not close with 130 VDC and a 60MA magnet.
>>
>> lar
>> Larry
>> K2JIA
>> OFC
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>>   
> A major use of solid state relays is  industrial and elevator control 
> equipment to replace  electromechanical relays   powering motors and 
> inductive loads. Because there are no contacts, nothing is eroded to 
> wear out and fail or stick. Also, the cut off is clean and there are 
> lower transits put onto the power line.  Fewer service calls, but the 
> flash and bang show is gone too!  The solid state relay uses scrs or 
> triacs to carry the load, usually with a small IC included to trigger 
> the devices at zero point so they are not switching  in the middle of 
> the wave.   For a teletype loop, look into high voltage MOSFETs or 
> IGBTs.      Bruce Gentry
>