Leaky120VAC solid state relay?

I have a 60 watt, 800 Lumen LED bulb (8.5 watts real power) that operates on 120VAC, but it blinks at about a 2 cycles per second rate when switched off through a large 25 amp solid state relay. The relay works fine on other loads. Is this relay leaky, or do they normally leak a little bit? I'm using

5 volts DC to drive the relay input.

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Reply to
Bill Bowden
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The relay may leak ohmically, but it may also have an RC snubber across its "contacts." The LED may have an input capacitor that charges up from any small current, and a switcher circuit that pops on at some voltage. Measure it!

Dimmers and motion sensors will often keep LED bulbs dimly lit, too.

Reply to
John Larkin

How are you applying the 5 V control signal? I've seen some ssr's that had a very high input impedance on the control, so if you hooked up a power supply to turn it on and then just lifted the +5 volt wire to turn it off, it would take several seconds for the input to drift down enough to turn the relay off. I don't remember if I saw any "flickering" where the relay oscillated on/off/on/off, but a pulldown resistor cured the slow drift. (I needed to drive a big ssr from a small mechanical relay built into a temperature controller so my signal was +5 or open circuit.)

----- Regards, Carl Ijames

Reply to
Carl Ijames

So put a smal "dummy load" across the LED bulb. 10K Ohms?

Mark

Reply to
makolber

There would normally be an RC snubber across the output triac- typically something like 100nF in series with 100 ohms. This prevents excessive dv/dt from turning the triac on when it should stay off (due to inductance in the load, for example).

That will conduct almost 5mA at 120VAC/60Hz ->

Irms= 120VAC*(2*pi*60*100E-9).

The actual leakage of the triac should be uA level at room temperature and the capacitor leakage should be negligible.

The AC supply in the bulb is probably charging up to beyond a UVLO cutoff level and then briefly switching on and discharging its supply capacitor, then it repeats ad nauseam.

An R or a series RC across the bulb should make it stop. The parts need to be rated for across-the-line safe operation. The series RC would waste less power than a simple resistor.

--sp

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Best regards,  
Spehro Pefhany 
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Reply to
Spehro Pefhany

That's a feature--a standby indicator! LED bulb indicates power-fail by _not_ blinking.

The bulb itself is full-wave rectifier-->filter cap-->two-BJT push-pull oscillator--> a.c.-coupling-->inductor-->bridge rectifier+filter cap-->LEDs.

It sounds like it's just rectifying the SSR's leakage current until the BJT oscillator starts, a relaxation oscillator.

Cheers, James Arthur

Reply to
dagmargoodboat

Many of then have snubbers internally.

the subber consist of a R and C in series, most of the time.

Jamie

Reply to
M Philbrook

Yes, that's about right. 10K resistor across the bulb slows the oscillation but doesn't eliminate it. 4.7K eliminates the oscillation and I read 23 volts across the bulb.or about 5 mA. But 4.7K would dissipate 3 watts when the light was on, and that's almost half the power of the LED bulb.So, I decided to move the plug to a mechanical relay. I have a remote control box with both mechanical and solid state relays. The light works fine through the mechanical relay.

.

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Reply to
Bill Bowden

Yes, it would make a good power fail testor that doesn't need a switch, just plug it in to see if it blinks. I have a neighbor who asked me to look at his TV problems since nothing was working. He had strung 3 or 4 extension cords in series and connected the TV to the end of the line which was dead. I used my electric fan to test the power and there was no power to the TV, or the digital converter box, or the amplified TV antenna. I finally got the TV and box working and then suspected the indoor antenna and suggested moving it outside to see if the reception was better. But he insisted the antenna was an indoor type and would not work at all outdoors. So, I finally figured out it was an amplified antenna and needed AC power and that plug was also dead. But it worked pretty well when we got it going. I was surprised and agreed with him that the antenna was definetly an indoor type and might damage the TV if moved outside. Too much signal level would degrade the picture and distort the colors.

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Reply to
Bill Bowden

If the SSR uses a triac, and is rated for 25A, it probably has a minimum hold current specification. Maybe you aren't meeting that with the small load.

Reply to
whit3rd

It works fine turned on. The problem is you can't turn it off.

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Reply to
Bill Bowden

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