Post by thread:[OT ] Problem turning off a solid state relay

I've got a couple of solid state relays that I would like to put to use but I've got a problem with them at the moment, I can't turn them off completlely. I've got 240 volts hooked up to one and I can turn it on using 5 volts DC. The voltage drop across it's terminals is only 2 volts when turned on and when I turn it off instead of the voltage being 240 volts across it's terminals it is 120 volts so therefore it's only half switching off. Does anyone have an idea as to whats wrong? Thanks in advance Regards Stuart P.S. I'll be using a PIC to drive this

yes they are SCR or TRIAC 's and you are measuring leakage Art spam_OUTartbTakeThisOuTcableinet.co.uk ----- Original Message ----- From: Stuart <.....pigKILLspam@spam@AR.COM.AU> To: <PICLISTKILLspamMITVMA.MIT.EDU> Sent: Saturday, April 15, 2000 3:22 PM Subject: [OT ] Problem turning off a solid state relay > I've got a couple of solid state relays that I would like to put to use but > I've got a problem with them at the moment, I can't turn them off > completlely. I've got 240 volts hooked up to one and I can turn it on using > 5 volts DC. The voltage drop across it's terminals is only 2 volts when > turned on and when I turn it off instead of the voltage being 240 volts > across it's terminals it is 120 volts so therefore it's only half switching > off. Does anyone have an idea as to whats wrong? > Thanks in advance > Regards > Stuart > > P.S. I'll be using a PIC to drive this

-----Original Message----- From: Stuart <.....pigKILLspam.....AR.COM.AU> To: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU <PICLISTspam_OUTMITVMA.MIT.EDU> Date: den 15 april 2000 16:22 Subject: [OT ] Problem turning off a solid state relay The most of the solid state relays needs a minimum at 3V DC trigger voltage, and you have 2V ? So what you have to do is advance the voltage to minimum 3 V DC and maybe the capacity of your source of power. Regards keN {Quote hidden}>I've got a couple of solid state relays that I would like to put to use but >I've got a problem with them at the moment, I can't turn them off >completlely. I've got 240 volts hooked up to one and I can turn it on using >5 volts DC. The voltage drop across it's terminals is only 2 volts when >turned on and when I turn it off instead of the voltage being 240 volts >across it's terminals it is 120 volts so therefore it's only half switching >off. Does anyone have an idea as to whats wrong? >Thanks in advance >Regards >Stuart > >P.S. I'll be using a PIC to drive this >

<x-flowed>>I've got a couple of solid state relays that I would like to put to use but >I've got a problem with them at the moment, I can't turn them off >completlely. I've got 240 volts hooked up to one and I can turn it on using >5 volts DC. The voltage drop across it's terminals is only 2 volts when >turned on and when I turn it off instead of the voltage being 240 volts >across it's terminals it is 120 volts so therefore it's only half switching >off. Does anyone have an idea as to whats wrong? Assuming that they are AC SSRs, there are two potential problems. You didn't say what kind of load you're testing it with. They don't like inductive loads (transformers, motors) and they also may not behave properly below some minimum load. Try it with a 100W lamp load and see what happens. It's OK to use 120 VAC for the test. Reg Neale </x-flowed>

Use DC SSRs for DC.. :) They are most likely looking for the 0 crossing and never seeing it. I think the SSRs you have are for AC loads.. If they are rated at 110 or higher, hook a AC lamp up and see if they work. Best regards, Giles {Original Message removed}

By their very nature, SSR's and Triac's will only turn off on a zero crossing of the AC power feed. This is why they are non-applicable to DC circuits. You can only control when they are turned on. David V. Fansler Network Administrator TriPath Imaging, Inc. (formerly AutoCyte, Inc.) @spam@DfanslerKILLspamautocyte.com <KILLspamDfanslerKILLspamautocyte.com> 336-222-9707 Ext. 261 Now Showing! http://www.dv-fansler.com <http://www.dv-fansler.com> Last updated March 31, 2000 Ann's Cancer, David's Observatory, Trip to Disney {Original Message removed}

If you can find one rated for AC or DC loads, then you will do fine. Good luck, Giles ----- Original Message ----- From: Edson Brusque <RemoveMEbrusqueTakeThisOuTFLYNET.COM.BR> To: <spamBeGonePICLISTspamBeGoneMITVMA.MIT.EDU> Sent: Wednesday, April 19, 2000 6:59 PM Subject: Re: [PICLIST] [OT ] Problem turning off a solid state relay > Hello, > > as we're talking about SSRs, someone knows if there's any SSR that works > with AC but can be turned off in any point (not zero-crossing)? At high rate > (above 20KHz)? > > Best regards, > > Brusque >

>By their very nature, SSR's and Triac's will only turn off on a zero >crossing of the AC power feed. This is why they are non-applicable to DC >circuits. You can only control when they are turned on. Unless you use a "Gate Turn Off" SCR where you do force the device to stop conducting by a signal on the gate. I have not used any of these, but do remember seeing datasheets for the early ones made by RCA. They did require some hefty drive signal into the gate to turn them off. I believe they have improved in gate turn off sensitivity since then, but do not have any figures.

The problem is that it's still the leakage voltage through device that you can measure i.e. 120v if supply is 240v. The meter you are using is also in the meg range put a lamp across the load and the take reading. Art {Original Message removed}

Try a GTO http://www.westcode.com/ws-gto.html Marcelo Y. Brusque wrote: >Hello, > > as we're talking about SSRs, someone knows if there's any SSR that works >with AC but can be turned off in any point (not zero-crossing)? At high rate >(above 20KHz)? > > Best regards, > > Brusque >

Crydom brand SSRs comes to mind. -----Original Message----- From: Edson Brusque [TakeThisOuTbrusqueEraseMEspam_OUTFLYNET.COM.BR] Sent: Wednesday, April 19, 2000 4:59 PM To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU Subject: Re: [OT ] Problem turning off a solid state relay Hello, as we're talking about SSRs, someone knows if there's any SSR that works with AC but can be turned off in any point (not zero-crossing)? At high rate (above 20KHz)? Best regards, Brusque