Solid state relay motion sensor?

[ffm]

Hi all,

Have a question for you all...Does anyone know of an occupancy switch that uses a solid state relay? Cant be the standard, electronic ones (ie the ones that you hear a click on switching), as the pulse from these is reducing the longevity of the cfl ballast's installed.

Cheers,

ffm

 

[Darkwood]

CFL shouldn't be really switched via a PIR for this very reason ...we live in the ERA of the LED now infinite switching without degrading the lamp life.

Solid state relays also produce spikes and as the nature of the load is inductive then the Lamp itself will create a back EMF to when switching.

 

[tazz]

You could always use the pirs relay to switch a solid state relay

 

[Marvo]

Solid state can also 'leak' causing flicker of lamps when they're off. I don't understand why you can't use a PIR with a relay output.

 

[ffm]

Cheers for the replies and in answer,

Marvo - cant use electronic relays due to the spike that occurs on "switching" - the cfls used here are cheap ie cheap ballasts, BUT, the unit units are dedicated so only take manufacturers cfl.

Tazz - good point and one that I have already fitted as a test to see if it works in the gents toilets.

darkwood - yeah, I know, and am a fan of the led but in this case the manufacturers also produce an led for these lamps for £6 - so am sceptical as to the quality. As to any issues relating to a back emf affecting the cfl, this is not likely to be an issue in this case.

So, do you guys or anyone else, happen to know of a solid state relay pir? Fitting them for this client would be the best option rather than adding a ssr downstream of the current pir or replacing the units.

many thanks,

ffm

 

[tazz]

As a matter of preventing back emf, a variresistor may help, acts like a diode on a dc circuit. many ac power supplies have them across the ac input

 

[Lucien Nunes]

cant use electronic relays due to the spike that occurs on "switching"

Sorry, I don't understand. An 'electronic relay' is a solid-state relay. Do you mean you can't use an electromechanical relay? As far as the ballast is concerned, this behaves just like an ordinary switch, so if they can't withstand being controlled by an electromechanical relay they would not be able to stand being controlled by a switch.

I agree that an SSR with zero-volt switching might be nicer to the ballast by minimising the inrush but I do wonder whether the problem is as much to do with how often they are being switched as the type of relay? Will be interesting to see the result of your test. Off-state leakage can be a problem with SSRs and small switched-mode loads like CFL ballasts. They can flash occasionally as the leakage charges up the reservoir cap. I had one like that, would flash about once a minute, annoying and possibly not good for the CFL.