Not if it's a mains load switching type with a triac or thyristor output,
they have no "R-off", they are either ON or OFF.
SSR's with an optocoupler inside are easily triggered by RF voltages
occurring between in-and output. You might try adding a ceramic Y-rated
capacitor (470pF ... 1nF should do), between the ground on the input
(optocoupler) side and the supply pin on the output (contact) side, as short
a connection as possible. Also one over the output pins.
**** Warning **** this may solve the problem but will add leakage current
between controller and mains. Check you stay on the safe side!
Another test could be just the 1nF Y-rated cap over the output (less likely
to help).This does not introduce leakage to the controller ground, just some
extra OFF-state current in the load.
Arie de Muynck
firstname.lastname@example.org (David Harper) wrote in message
With the turn-on time being ten times the turn-off time, I don't
expect that false turn-on will be a result of LED emitter modulation
at the interfering frequency.
Fet structures usually have a hefty input capacitance; the coupling
capacitance to the gate is piddling by comparison.
Biggest coupling capacitance that could produce false gate turn-on is
from the two drains. Is there a fairly large amplitude of RF voltage
present there? These thinga are really only isolators at low frequency
or DC, unless a voltage close to at least 1/10 their rating exists
email@example.com (R.Legg) wrote in message
OK, but I've seen SSRs used at broadcast transmitter sites running
many kilowatts of RF with no problems. SSRs are like Rank telecines.
When you see it 'misbehave' don't assume it isn't being 'told' to do
1. It's very likely. In my classes, I've been taught that EMI can bugger
up the proper working of just about any circuit, so it should always be
taken into consideration.
2. Er, I think it's a simple matter of induced current in the line
giving false hi signals.
3. First thing I'd do is make absolutely sure your relay coil is
grounded rather than floating when in the "off" state. Being assured of
that, if the problem persists, you might want to try a simple RC
band-elimination filter. If you do not have it handy, I can give you the
formula to determine the R and C values.
I apologize in advance if your electronics knowledge is more advanced
than mine and I've just wasted your time.
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